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Welcome to BugBits' technical pages

These pages have been put together as an aid to anyone who is considering building, or having built, a type 1 VW engine for use on the roads.

The contents of this document have been put together using 12 years of my experience on Beetle engines along with books I have read and people I have spoken to. I raced a Beetle in Guernsey as a hill climb car, it went through different stages of development as did my knowledge, and it is this learning by trial and error I wish to help you to avoid. Since then I have built engines, both standard and performance, for other people.

I have written a How To page that will explain each of the following section in detail for those who have never had the opportunity to strip a type 1 engine. I would suggest you visit that site now, print off a copy of the text and return to do the same with this one.
Go to the How To site now.


What do you want
Crankshafts and flywheels
Cylinder & piston sets
Cylinder heads
Camshafts and the valve train
The oil system
Running for the first time
Useful data


So you want a not out of the box engine for your Beetle, what should you do about it. There are many, many parts available for your engine, just take a look inside any VW mag and you will see ads for parts you have no idea what they are, but sound impressive. The most important part to building your own engine is not to jump straight in, read, ask and observe where ever you can. My let down has been living in Guernsey (a small island off the north French coast of only 30 square miles), when I started racing in the 80's there was almost no-one I could ask locally who had any idea that a Beetle could produce more than just a whistling sound, let alone 200BHP, so I had to learn by my own experience and by long phone calls to Autocavan (sadly now closed down) who helped without really knowing my full requirements, as nor did I. How could I know what I wanted until I had experienced it, and without a car how could I experience it? I wasn't going to enter a 1600cc Super Beetle with standard road tyres up against 2 litre Ford twin cams boasting huge amounts of power, my vanity was to great for that.
I am hoping to try and pass on some of my experiences and save you experimenting as I did. Throughout this document I will try to give you calculations and comparisons to make it a little easier to make the right choice. You will still have to make the final choice as I cannot tell you what to buy, just what ball park to look in.

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What do you want

One of the hardest parts of building an engine is deciding what you really want, are you intending to take granny to church on Sunday but be able to keep up with your mates each evening, or are you after something a little hotter, such as 100 - 150BHP. If you intend to go beyond the 150BHP mark then this document is not really for you, only so much can be covered and all out engines, especially when used on the road, require so many areas to be considered together that one could fill a book with the possibilities as have people like Keith Seume with his very informative book 'Aircooled VW Engine Interchange Manual', which is a 90's version of 'How To Hotrod Your VW Engine'.
Firstly, how much money are you prepared to spend? Now if you double it that will give you an idea of what it will probably cost. I built a 110BHP engine for a lad who came to me and said 'I have 1000 to spend, I want.....', and proceeded to list 3000 of parts alone. When he finished I calmed him down and explained what things cost. He finally spent 1800, and went away happy.
What sort of power range did you intend to have, 50-75BHP, 75- 100BHP, 100-150BHP? To give some idea of the expected cost, I use the formula BHP X 20, this gives an amount that turns out to be closer than just pricing up the crank and carbs.

One thing you should be aware of, VW made their parts much too strong for what they were intended, meaning you can retain a large number of parts from your donor/existing engine.

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Type 1 Super Case There are many crankcases available, your original case, a new original case, a clearanced case and race cases, they are all good for what they were built for. If you intend to keep your original case and want anything over 75BHP you should only do this if it is a twin port, that is one whose serial number begins with two alpha characters from AB to AS. They should also have the part number AS21 or AS41 (this is on the side under the pushrod tubes). Apparently the AS21, produced after the AS41, has a greater aluminium to magnesium ratio than the AS41 and therefore handles heat better, although I have never had any trouble with an AB 1300 case (AS41) up to 180BHP, but I have never used one long term on the road. Gene Berg has done much work looking into the differences and advocates the use of AS21 rather than AS41, but I have not found any noticeable difference.
Old or new? A lot of people feel the need to align bore a case just out of habit, but I feel this is not really necessary. If you journals are in need of machining, then yes, machine them, otherwise leave well alone. Take the case to a machine shop and ask them. Also get them to check the flywheel thrust face, this will probably not be obvious until you go to set the endfloat and find it is several millimeters instead of just fraction of one. A new case is the best way to go, but on a budget this is not always easy. You can buy reconditioned cases, but personally I'd say no, don't.
Case studs were also changed from about 1975 for 8mm rather than 10mm. The reason for this is that the 10mm studs stretch once heated more than the 8mm, once again I've never experienced any trouble with the larger studs. One advantage to the 8mm studs is that they already have case saver inserts fitted.
It is possible to obtain case savers, these are stud sleeves, which requires the case being tapped to 12mm or 14mm where the old studs went, then inserting the case savers, then the 8mm or 10mm studs go into them. Be warned, if you plan to open the case up for 94mm cylinders you will experience trouble with the inserts encroaching in the holes, and remember a steel insert will not bore anything like as easily as the mag/alloy case, in fact it will probably destroy the cutting tool.
The next case up is a clearanced case, these have been machined for 90.5/92mm cylinders and the insides have been opened up to accept an 84mm crankshaft. These cases are very good value for money when you consider the cost of a new universal case and then the machining costs. These cases often have the oil gallery bored to allow the insertion of an external oil filter, which is useful and will save a few quid getting it done later (by the way, these are my favourite choice of case).
Race cases come from the top names, Autocraft, Bugpack, Pauter, Rimco and Scat, but they aren't cheap. Use one only if you feel you really have to, or you're a chap I know who won't buy what will do the job, he has to have the most expensive. They are, however, very strong, sometimes heavier than a standard case, but really not necessary for a road going 150bhp engine. Put the money into something that will make your car go faster, you'll feel better doing that.

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Crankshafts and flywheels

If you plan on using your engine at over 5500 rpm, which is quite likely and the best way to give you more speed and power, you can forget using your stock crank. There are, like most other parts, loads of different crankshafts on the market, the bottom of the range is a welded counterweight 69mm crank. The counterweights are what allow you to exceed 5500 rpm. All cranks I will mention from this point will have counterweight on them, either welded or forged from new.
In case the words "counterweights" are just words to you, here's what they do. The big end, the bit the con rod bolts to, is offset and so will pull the crank in an uneven circle, in fact it will put pressure on the bearings. Imagine a fairground ferris wheel with only a quarter of the people on board and all together, once the speed increases the strain on the frame holding the wheel up would be immense, so the speed would need to be kept down. If you now fully loaded the wheel, the speed could be increased, as despite the extra weight, it was distributed evenly. The same effect happens with the crankshaft, so by fitting a counterweight, the extra people, the crank can rotate faster. A faster rotating crank, a faster moving car.
Counterweighted Crankshaft After the welded counterweights comes forged cranks, these come in many different sizes from 69mm up. There are two crankshafts I would recommend, firstly a 69mm, either welded or forged, and a 78mm forged. These two will give you reliable horsepower from a 1585cc up to a 2007cc from a standard case.
Crankshafts over 69mm are referred to as 'strokers'.
The advantage of using a 69mm crank is that it can rotate faster than a stroker (a smaller circle and therefore less distance to travel to complete the circle). Remember an engine is an air pump, the faster and easier you can get the air in and out, the faster the engine will go. So with that in mind, you can see how a short stroke, although giving a smaller capacity and theoretically a lower power output can run faster and give a higher rpm. For street use this isn't always a great advantage as it requires the revs to be quite high to get full benefit, but if you intend taking your animal to the strip it could work well. Of course this then requires a lot more head work and getting the exact camshaft for your needs.
All 'aftermarket' (that I'm aware of) cranks come drilled for 8 dowel pins, these are the bits that keep the flywheel turning with the crank. The more pins the more chance of the flywheel staying attached to the crank. The nut that holds these two together needs, as standard, 250 lbs/ft (35mkg) which is quite an amount of pressure. To give you some idea of what that means, if you hang 18 inches (45cms) down a bar with a socket on the end you would need to weigh 165lbs/75kgs (12 stone) to get it to torque. For a high powered engine I would recommend about 400- 500 lbs/ft (55-70mkg), this means if you do weigh 165 lbs you will now need to be between 2.5 and 3 feet (75-90cms) down the bar. All that weight on a 36mm headed bolt, wow.
The journals (the bits the bearings go on) are available in many different sizes to fit different con-rods, so you need the matching size con-rods (see that section), but why cause more expense than is really necessary?
There are also flanged crankshafts, these have a larger flywheel end which allows for better mating with the flywheel, but does need a special bearing set and a matching flywheel. More expense.
Whilst on the subject of flywheel mating, there are wedge-mated crank and flywheel sets available. These have been machined with a taper on both the crank end and the matching flywheel face, this does work well, but remember, you might be the one who will have to separate them one day. They work just like steering rod ball joints, have you ever tried to get one of those off? But, once again, if you intend to stay below 200BHP you will never need one of these.
There are heavy duty nuts and larger washers available, they are usually made of chrome-moly steel. They aren't generally needed as the standard nuts will take at least 400lbs/ft (55mkg) and who needs a larger washer (they are meant to keep the dowels in place), where are the dowel pins expected to go? Having said all that, they aren't expensive.
Your flywheel, apart from requiring the extra 4 dowel holes should be machined to weigh between 10 and 13 lbs (4.5-6 kgs), the weight must be removed from the outer most edge (not the teeth) and most machine shops will be able to carry out this operation for you. You could always buy a ready cut flywheel, but of course you will have to pay for a flywheel that you already have and then you'll have one spare when you've finished.
Once you have your flywheel and crank ready, fit the #3 bearing and the two drive gears, get your clutch pressure plate and take them to a balancer, it is well worth it as it allows for a smoother running engine along with the fact it will should help your engine last longer.
Whilst I'm on the subject of longevity, it should be noted that if you increase your power output you can expect parts to wear out a little more quickly, and so doing everything you can to make the engine run smoother will slow this degradation. I will point out anything to help this as we go.
One last point, there are shims in between the crankshaft and the flywheel, these set the crankshaft endfloat. The recommended gap is 0.07-0.13mm (0.003-0.005in), open that up to about 0.25mm (0.010in) if your engine is going to be over 120BHP. This will allow the extra heat to be dissipated better from the crank and crankcase without binding (NB the case and crank expand and contract at different speeds).

To help you decide the length of stroke you require, use this calculation, Bore X Bore X Stroke X 0.0031416.

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Performance Rod Set Once again, there are many rods available, your standard rods (use type 311, this will be cast into the bottom of the big end) should be good as they are for most engines up to 100 BHP and with a 69mm stroke crank. Once you go to a longer crank you will either require these rods to be machined or to buy a set of previously cleared rods, the advantage of buying a set of rods is that they will have been balanced end for end and as a set, which will help your engine's longevity.
Like crankshafts, con-rods are available with different journals, and like the crankshafts you have no need to change from the stock VW 55mm diameter.
Rod length is also an area to look into as this can move the power band like a cam, higher or lower in the rev range. The length of the rod and the length of the crankshaft stroke give the rod ratio. Rod length (mm) divided by the crank stroke (mm) = Rod Ratio. The lower the ratio the lower the power band, the higher the ratio the higher up the range the power band will move. As a comparison the stock 1600cc set-up is 137/69 = 1.98, now if you wish to hill climb you will require a lower ratio (I had a ratio of 1.76) and if you wish to drag race a high one.
Chevy 327 rods are 145mm long, are strong and cheap (in the US), but will require some machining as the big end is only 51 mm instead of the 55mm of the VW, this does save on changing the crank just to match the rods. These used with a stock length crank will give a high revving engine with a high power band, giving a rod ratio of 2.10, ideal for a small bore drag engine. The Porsche 912 rod is a little shorter than the VW, but when it comes down to it the VW is stronger, not a bad length and it fits. The is the key to keeping the price down, get things that fit each other.
This is the theory of rod ratio.
A long rod will give a slower piston speed, and therefore a longer life for the rings and cylinder walls, but this also causes the cylinders to fill up slowly when the piston moves down during the inlet stroke. Of course, once the rpm builds this is overcome, hence the higher power band. A shorter rod will, of course, fill the cylinder much faster and therefore give more power at lower engine speeds, but be limited to a lower rev range.
There are many aftermarket rods available, but like crankcases I can see no reason to change to a set of rods costing more than I sell a complete recon 1600cc engine for.

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Cylinder and piston sets

Cylinder and Piston Set There are only a few choices here, you can go for an 88mm or a 90.5mm, in either a stock or long stroke design. DO NOT EVER USE A SLIP-IN SET as the cylinder wall are too thin to withstand road use for any length of time. For the same reason I, along with many others, do not recommend the use of 92mm cylinder sets. These have the same outside diameter as the 90.5mm sets, but obviously have a larger inside diameter, thereby giving a thinner wall. As Dick Nuss would say "Boo 92s". I had a set of 92s which, after only 2 race meetings, had four shiny lines up and down the cylinder and four beautifully untouched lines. This was caused by the cylinder becoming squared to the four head studs and the rings then binding on the walls. Don't let this happen to you as it costs much more and takes longer to strip down a road going engine.
Always use a forged piston if you can and use Teflon Buttons. This comes back to one of my first comments that something sounding good, but you don't know what they are. Teflon Buttons replace the clips that hold in the wrist pins (the bit that hold the piston to the con-rod) and won't come loose like a clip can. They are small mushroom shaped buttons that slide against the cylinder wall and being Teflon don't wear out, supposedly.
One other part to be aware of is total seal piston rings, these have no breaks in them and therefore give better compression. I have never used them and so can give no comment on their ability, longevity and cost.
Here is the calculation for CC, Bore X Bore X Stroke X 0.0031416.

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Cylinder heads

You can buy some lovely heads from the shops, but know now that they all need finishing off. No head can be built for your requirements and be a standard 'off the shelf' number. All of these heads will improve your engine as they are, but you should always consider a little head work at a recognised VW porting shop.
If you plan to stay under 100BHP then you can happily use your standard VW twin port heads without any work, less a good clean up. Don't bother with single port heads, change to a pair of twin ports.
An Eliminator Head You can buy 040, 041, 042 and 044 heads, these are all based on the standard VW head, but still require work to perform well, especially the 041. The 040 has 40mm X 35.5mm valves, the 041 is similar but has 39 X 32 (not much better than standard, as a recommendation, don't use them), the 042 is a development of the 041, but with bigger valves, 40mm X 35.5mm. The 044 is the best of these heads and has more metal in the important areas near the valve seats and plug hole and therefore requires a long reach spark plug. The extra metal helps prevent cracking, a common problem on all these heads, including your standard heads. Of these heads I would recommend the 044 greatly over the other 04 heads and would seriously shun the 041.
My personal favourites for road use is the Eliminator which has plenty of metal in all the right places and with only a little port polishing they run very well, although they do need long reach spark plugs. Beyond these are those from all the top names, these come from Bugpack, Gene Berg, Pauter and Scat, but remember like any 'off the shelf' head, it will still require some work to make it perform at its best, so the more money you spend on a pair of heads there is still money you will need to spend.
Have a look through the catalogues and speak to the vendors, sum up the best value for money, but don't buy heads that are too big for what you want. Only buy an inlet valve size you can fill.
I won't go into heads any further as your requirements are something only you know, so go and speak to a head shop, let them know what you want and see what they say. If they know what they are doing they will recommend a head and then be able to machine it to your spec.

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Camshafts and the valve train

Cams, like heads, are a big area, you can really mess up an engine with the wrong cam, even more so than with heads. A 1679 with Weber 34ICTs and standard heads will not run with an Engle FK98 cam.
Cams have two main measurements, the lift, in either millimeters or inches, and the duration in degrees of the crank. The duration is the time the valve is opened for, the longer this duration the more fuel gets into the engine and the bigger the bang when it ignites. Well, that's the theory, in actual fact the longer the valve is open for the faster the engine needs to be running for this to happen, so at idle the engine will not run all that well. For street use you should not consider anything with a duration of greater than 290 degrees. The most popular cam I have ever seen used on the street is the Engle W110, it has 286 degrees and 0.431" (10.95mm) valve lift. Engle also make the W100 which is often better used on an engine under 1700cc or heavy weight cars (I use on in my 1776cc crewcab). The duration of this cam is only 276 degrees which brings the power band down where a smaller capacity engine needs it.
Remember this: The longer the duration the higher the power band, and subsequently the lack of power in the lower rev range.
Camshaft Cam lift is usually measured in inches ('cos most manufacturers of VW cams are American, despite being for a German car, don't ask) and either is at the valve or the cam, so make sure you know which before deciding on one. There are different rocker ratios as well, the standard rockers multiply the lift by 1.1, whereas others have ratios of 1.4:1 and 1.5:1, this of course means the cam lift is multiplied by 1.4 or 1.5 to give full valve lift (less the rocker/valve clearance, usually 0.004"/0.1mm for inlet and 0.006"/0.15mm for exhaust, keep this to 0.006"/0.15mm for both on a <100bhp engine). If you intend using higher ratio rockers, check the cam card closely and check if you can/should run a ratio rocker with it. The more lift you have the more fuel goes in and the bigger the bang when it ignites, so the higher the lift the more fuel (well, it almost works like that). Most manufacturers have their popular street cams, I've mentioned Engle's, Bugpack have their 4062-10, which gives a little less lift and a little less duration, Scat have the C35, Gene Berg has his GB297, slight differences, but all much the same. Any of these cams will work well on the road throughout the rev range, plus give increased performance over the standard cam. They all have around 284-286 degrees and about 0.415 - 0.451". If you want a little more lift without the extra duration, my personal road choice is the Engle VZ25, but these do work better with modified heads.

If you insist in going over the 290 degree barrier, then it's your own fault when it's a bit sluggish in town. Valve lift is not quite as bad, but please use 1.1:1 rockers as there are very few road cams that are designed to use a 1.4:1 or 1.5:1 that work any better than an equivalent one designed to run on 1.1:1 rockers. Still try to keep your total valve lift to below 0.500" as this is the limit of a standard head. Forget the 1.25:1 rockers, they really don't give enough extra for the price you pay.

There are adjustable cam gears available, don't buy one. You cannot set up the cam better that it was manufactured. If the cam doesn't match the cam card it came with it is either a faulty cam or a faulty cam gear, so take it/them back. There are also straight cut gears, these prevent cam lash caused by the synchromesh type gear, but as you won't be running dual valve springs, you won't need these either, plus they are so noisy.
Dual valve springs are available to fit any head, don't buy them, you don't need them for street use and they slow your engine down. Any extra work you make your engine do, like open valves with more springs on than they need, will slow it down. A new set of single springs is a good idea, as this will keep your valves closed when they should be closed because twenty five year old springs don't work as well as they did when they were new.
Dial Indicator You can buy chrome-moly pushrods, don't. You can and should consider 'cut to length' steel pushrods, these will return your rocker arm geometry back to the way the factory made it, efficient.
Rocker arm geometry: This is getting the valve opening through the full swing of the rocker arm. To set this up, you will need to get a soft spring the same size as the valve spring (you can use the inner spring from a dual set) and fit it. Make an adjustable pushrod, this is done by cutting an old pushrod in half, removing about 2cms (3/4 inch) from one half, tap and inserting a length of M6 thread with a nut on it tight into one end and drill out the other half to 6mm so the thread slips in.
You'll only need the case, cam, one cam follower, crank with one rod on, one piston without rings, one cylinder and one head (obviously you can have an almost complete engine, this is just the easiest way to do it). Reduce this adjustable pushrod to its shortest. Assemble the part mentioned with no pushrod tubes on. Set the rocker adjusting screw to half way, and extend the pushrod until you have a valve clearance of 0.006"/0.15mm, turn the engine over until the valve is half open (you will need a dial indicator for this), at this point the rocker arm should be level with the head's rocker cover seat (valve top and pushrod top are level). If not, adjust the pushrod and with rocker stand shims and valve lash caps (if necessary) until it is level. Recheck and if OK you can cut your pushrods. I use a lathe for this as I can get the rods to finish better and be more accurate than using a say or pipe cutter.
When you come to push the ends in after having cut them to length, use a large hammer and a pair of old cam followers. You will have eight of them floating around after putting new ones in with your new cam. You must use new cam followers with a new cam, and not just because the bloke selling you the cam tell you to. Look after your cam and it will look after you (or was that something else?).
You can buy hydraulic cam followers and large base followers, don't. There are light weight followers, I've never used these, but there is no reason you shouldn't spend your hard earned money on them. Like I said about not using double valve springs, if you have lighter cam followers the engine will have less to lift and also return to base a lot faster. This will be of benefit, but you probably won't notice it.
There are many different valve types available, but use those that come with your heads, they will probably be stainless steel and all in the price. For road use you don't need sodium filled titanium valves at several hundred pounds a set, or anything else too special.
When you install your cam do use the paste they supply with it, in fact splash it on all over the cam and the follower bases, plus do run the engine as the instruction says.

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The oil system

High Pressure Oil Pump Take a look at an oil pump, it consists of two gears and a case, not much to it. The oil is picked up from the centre of the engine (above the oil draining plug) and enters the pump on the right, leaves on the left and heads for the first pressure relief valve (the one below and to the left of the pump), if the oil is hot it is sent to the oil cooler, if not it goes straight to the bearings via the oil pressure switch. Once here it feeds the camshaft, the cam followers (which in turn feed the rocker shaft through the pushrods), the crankshaft and the big end bearings and then the small end bearings. The last part of its journey is through the second pressure relief valve (this is near the flywheel end), this keeps the oil pressure to its set value.
You can replace the relief valves and springs with higher pressure versions, these aren't really worth the effort, as the standard version works well, although new springs wouldn't hurt. These are often just a longer piston rather than a longer spring, but sometimes you get both. The spring/valve nearest the oil pump is the oil cooler bypass and will open when the oil is thick and cold to prevent the cooler from blowing out. If this valve jams open you will not get your oil properly cooled, or if the valve remain closed you might blow the cooler out the next time you run fresh oil on a cold day. The front spring/valve (nearest the flywheel) is to retain a minimum oil pressure. You can replace the oil pump with a higher pressure version, these are the same design except have larger gears in a larger case. I would not ever run a high pressure oil pump with oil pressure boost springs.
There are oil pump covers available with an outlet pipe, which is to allow an oil filter to be added. You will have to block the pumps normal outlet by pushing a bung into the hole in the case (you should tap the case and use a length of thread with a screw slot in so it can be removed later, if need be), then drill a hole in the case (you can see the raised part of the case that goes up and to the left at 45 degrees from the pump, follow that up until it comes to a lug in the case facing toward you and use that as your return point) tap this to 1/4 BSP (this is the standard thread type used in oil systems) and connect your filter. Use externally braided hose, as being so close to the ground and near so many other parts it will need protecting from damage. Do not fit your filter where it can be damaged i.e. inside the wheel arch or too near the ground. DO NOT FIT AN OIL COOLER ON THIS PIPE.
There are also dry sump pumps, these are a two stage pump, the first is the oil in, this takes oil from a separate tank and pressurizes it into the engine. The second stage is the oil recovery which is twice the size of the first and sucks the oil up from the bottom of the engine and returns it to the tank. They are not all that common on road cars, their main use is when an engine is pushed from side to side a lot, such as off road. When using an engine in this way the oil spends a lot of time being pushed into the heads and therefore not near the oil pickup, so seizure is waiting to happen. These pumps are expensive, they require an extra tank, a lot more hose and some case machining. Don't bother with one for the road, you don't need it. I used one for hill climbing as without one I could not have gone around the bends quite as fast.
There are sump baffles, these work quite well. They are a simple drilled plate that slips into the case just below the camshaft. The idea is to prevent the oil easily running into the cylinder heads on cornering and starving the oil pickup.
I have used and am happy with an oil suction kit, this consists of a new sump plate with an extension to the oil pickup that fits very close to it. The idea being, it only requires about 4mm of oil to still be able to pick it up, the standard pickup requires about 10mm.
You could consider a high capacity oil sump, these add about 1.2 pints (0.7 ltrs) of oil to the engine. They come with an extension to fit onto the standard pickup which collects the oil from the new tank. They have one major disadvantage, they hang about 3 inches (75mm) below the engine and can cause a problem with a lowered car. The idea here is that they do not give you any cooler oil, but it does take longer to heat and you have more supply when cornering and therefore less chance of seizure.
Mini sumps work like a mixture of the last two sumps, they have an extra mini sump along with an extension pickup. I still prefer the oil suction kit.
Coolers: There are many different kits available for cooling your oil. If your engine's oil regularly rises above 120 degrees C you need an external cooler. These use an adaptor that fits in place of the standard cooler and has two connecting pipes on, one in and one out, which point towards the flywheel. Some kits come with fitting instructions that show the cooler fitted to the fan housing inlet, whoever thought of this should also be strapped to the fan intake themselves. The air going into the fan housing should be as cold as possible, warming it up with an oil cooler is rather defeating the object. Fit your oil cooler somewhere under the car, along side the gearbox or somewhere where it is out of the way of any passing objects, but close enough to the fresh air.
Don't run an oil cooler from an oil pump outlet plate (as mention earlier) as this will send cold oil to the cooler when you start your engine in the morning which will cause extra stress on the cooler and could blow it out. That's what the first pressure relief if for, it only sends oil to the cooler if it's hot. That is why I cannot understand the shops selling uprated rear (cooler bypass) relief springs and pistons.

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009 Distributor What ever you may read, you cannot gain any extra power by changing your distributor, ignition leads, coil, or spark plugs. You can help the engine to run smoother and more efficiently, though. Your choice of distributors is limited to your stock unit, the Bosch 009 or 050 in either a standard configuration or with a Lumenition Optronic system or other electronic pack. These electronic units will help your engine run smoothly and with a more accurate spark, but remember to take a set of point with you on any long trips just in case they pack up, otherwise you're knackered, they cannot be fixed. If you change your carbs for a dual system you will need a purely centrifugal advance distributor. The 009 and 050 are of this type. The difference between the 009 and the 050 is the advance rate, the 050 gets to full advance faster rate than the 009, meaning it gets to its full advance at a lower engine speed, this is not a good idea for a lower powered engine (under 100BHP) as it will put more of a demand on the engine before it is really ready to give it.
Magnetos, they don't use a coil and are very expensive. They are mostly used by high revving drag race engines. A coil and 009 is a far, far better and cheaper option for a road car and one of the most common set ups.
Coils are available in many different types, but they are all basically the same, a coil of wire in an oil bath. The most common coil seen on the Beetle is the Bosch Blue, this is a good unit and will give you many happy hours, well, years. The choice is almost endless, they are made by more names than I care to mention, and nearly all of them will do what you want, but for the price, and ease of availability, there is no reason you shouldn't get a new Bosch Blue. Don't buy used coils, they rarely go wrong, but they aren't that expensive to take the chance.
You can change to silicon ignition leads in both 7mm and 8mm sizes and in many colours (the silicon part is the wrapping). The size of the lead isn't important to a road car, but colour obviously is (only joking). Your original leads will work well, but a new set can't hurt and they aren't expensive. You can get deals which include a 009, Bosch Blue coil and a set of silicon leads.

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Let's start by reminding you of one of my earlier statements, an engine is an air pump, the faster and easier you can get the air in and out, the faster the engine will go. You must remember, though, if you are running a standard carb and change the air filter for an aftermarket type which will flow better than the standard VW unit you will need to increase the main jet on the carb. Note: More air needs more fuel. You can buy adjustable main jets for the Solex 31 PICT-3 or 4 and the 34 PICT-3 as used on the 1300 and 1600 twin ports respectively. It is a better idea to buy an adjustable main jet, as trying to guess the jet you need could be expensive before you finally get it right.
Carb choices are getting smaller. The 48IDA was always used with the big engines, but Weber don't make them any more which is making them difficult to get hold of. The Americans used to use the Holley Bugspray for the street engines whilst in Europe we used the Weber 32/36 DFEV. The Bugspray is no longer available new, whereas the 32/36 DFEV is still going strong. If you can find a Bugspray it will help a small capacity engine run much better, and an engine up to 1800cc will like the 32/36 DFEV. The Weber is a progressive twin choke, this means that the first 32mm barrel does all the main work until you floor the accelerator and then the 36mm cuts in, which you will notice. There was, and I think there still maybe, a set of Kadron Solex carbs, these are two single 40mm Solex carbs on individual manifolds with a crude linkage (which often loses one of its retaining clips). Having said that, they are good value for money, as are any other twin single carbs sets.
After that comes the best of the rest, 34ICT, 40IDF and 44IDF. Dellorto also make an equivalent range, 34FRD, 40DRLA and 45DRLA, the only difference is the Dells are usually a little more expensive (due to a smaller demand and, in my opionion, better quality), but if you intend using a blow through turbo system you can forget the Webers, they can't handle the pressure as well as the Dells. The 34ICT/34FRD are great for a small engine up to 1800cc, it gives a good response and is much better on fuel consumption than the 32/36 DFEV. The 34FRD, Baby Dels, are now no longer made. If you can get some, do, they have two separate single carbs, one above each head. The 40IDF/DRLA and 44IDF/45DRLA are twin chokes, which can be used as either single centre mounted or as two side mounted carbs. The single centre mounting doesn't work well 'out of the box', but if you can get it jetted correctly it should run well, although icing is more common with this set up. The best way to run these carbs is as a twin set up with one either side of the engine. They usually come as a complete set with manifolds, air filters, linkage and fuel line. They run well on any engine from 1600cc up, although I would use the 40IDF/DRLA for 1600-1800cc and the 44IDF/45DRLA from 1800-2000cc.
In my opionion the Dellorto has a far superior linkage system that the Weber, it uses a hexagonal rather than a round bar, which means the arms don't need bolting up so damn tight, but have a look at them both and see what you think.
Twin Dual Weber 40IDF Set One point to note, you are likely to have problems using your standard fuel pump with these dual twin carb set ups. They work well until you reach about 4,500 rpm then can start to struggle. Electric pumps are available from many outlets and some are designed to replace the existing pump and sit on an adapter next to the distributor, but most pumps should be run from as near the tank as possible, as they are designed to push not pull the fuel. There is a nice recess on the opposite side to the master cylinder along side the front of the floor pan framehead.
You can use 48IDAs on the road, but you will get better mileage and easier town running from a set of 40 or 44/45s.
If you plan to run a set of 40s on an 1800, do ask the shop for a set designed for this engine. The set-up the 40s come with is designed for a 1600cc engine, using 28mm choke and 115 main jets, where an 1800cc engine will require 32mm chokes and 128 mains. Use these calculations for your carbs:
Determine carb size: (Square root of (cylinder cc X maximum rpm)) divided by 40 (I would suggest a maximum rpm of 6,500 to 7,000)
Determine choke size: (Carb size X 40) divided by 50
Determine main jet size: Choke size X 4

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OK, let's go back to what I keep saying, an engine is an air pump, the faster and easier you can get the air in and out, the faster the engine will go, so an exhaust with as little restriction as possible is the key to this. A twin quiet pack will allow the gases out easier than a single, because each silencer only has to handle half as much exhaust as a single, QED.
Dual Quietpack Exhaust You must be aware of how an extractor exhaust works, as there are many on offer that are not extractors. To make an exhaust work to help the engine you will require the four pipes to meet together at the same time, that is the four of them must be the same length. Due to the extra length required to get from cylinders 1 and 3 (nearest the front of the car) you need to make number 2 and 4 longer. Look at most performance exhausts and you will see a great winding of metal, this is to make up the extra length required for the back cylinders. These four pipes must then merge into a collector together, this creates a small vacuum in the collector whenever one pulse passes. To put it another way, when number 1 cylinder exhaust passes through the collector it produces a vacuum in the other three pipes, as number 4 is next it will be pulled down the pipe, so helping the piston. The smoother and straighter the pipes are the better this system works, unfortunately this pushes the collector so far out the back it is just not practical for a road car. In America I'm sure they can get away with it, but in Europe we have smaller roads and in Guernsey we have them even smaller, put it this way, Guernsey has a very high case of broker door mirrors, on both sides.
To continue the process of helping the gases escape, you can use a "Stinger" which tapers out for about 18 inches (45cms) and aids this vacuum effect. Of course, using a stinger on the roads is asking for trouble, not only are they loud, but they stick out the back so damn far.
You may want to exchange your heat exchangers for "J" pipes, these are simply a replacement, they do not really aid the exhaust much, but do make the engine lighter. You will have to make some new brackets for the lower tinware if you use these.
Don't expect the following exhausts to help the engine in any way, other than keeping it quiet: Bugpack Universal Exhaust/ JSC Economy Header & Muffler and GT Exhaust Systems, any dual exhaust (used on buggies/Bajas), Monza Performance Exhaust, Zoom Tubes/Zoomie (these are very 1970s). Use your discretion, if it doesn't have a merged collector, it isn't going to help.

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Cyliner Cool Tins When an engine produces more power, it subsequently produces more heat. This means that cooling is more important now than before. I always fit a new thermostat to a performance engine, as the cost far out weighs the trouble caused if it doesn't work. Another favourite of mine is the Cylinder Cool Tin, these are a copy of the Type 3 under cylinder deflector. They cause the air coming down from the fan housing to wrap around the lower part of the cylinder far better than those tiny little plates you have already. Never run an engine without a thermostat and the associated flaps. I've heard people say things like, "the daily temperature here is over 100*F", ok, but the operating temperature of your engine is about 80*C.
You should also use a cylinder head temperature gauge and connect it to cylinder #3 (as this is always the hottest). The senders for these gauges fit under the spark plug like a washer, but be careful as they are easy to break. I have, in the past, connected them to a cylinder head bolt, the upper one second in from the left on the left hand head, but this does mean drilling the tinware and more importantly, they are there to stay once the tinware has been fitted.
If you have fitted an external oil cooler you can change your fan housing for one other than a "dog-house" type (that's the standard type used after 1971). You must remove the control flaps from within your old fan housing and transfer them to the new aftermarket one you have bought. The reason for this is that those flaps allow the engine to reach its correct operating temperature quite quickly and thereby reduce cylinder wear to a minimum. Be aware that many of the aftermarket fan housings don't fit too well and do not have provision for the control flaps, if this is the case, don't buy it. You really can't do much better than the standard post 1971 fan housing, but remember if you are going to remove the oil cooler you will need to patch the back of the housing to keep the air in.
Power pulley are smaller pulley wheels which turn the fan slower and therefore require less power from the engine, that means the engine will not receive all the air it needs. It is worth noting that if you intend running your car in and around town, the power pulley is not for you, but if you plan on running your engine at high RPM for any length of time i.e. drag racing, you should consider one as the standard fan doesn't work very well over 6,000RPM (engine speed) and by reducing its speed it will extend the usable range of the fan. Please remember, if you use a power pulley in town, you are asking for trouble. There are also dry sump pump pulleys available, these are even smaller and have been designed to run with this huge pump. As I have already recommended you don't use a dry sump pump, you don't need to ask me about these pulleys.
My final point on cooling is this, Volkswagen spend a lot of time and money working out the best way to cool their engine, so what makes you think a badly fitting aluminium 36hp replica is going to work any better.

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3 Puck Feramic Clutch Plate Not too much to say about clutches, just don't use a feramic centre plate for use on the roads (the feramic pads get stickier the hotter they get, so you cannot slip them, therefore no good in town) or a pressure plate heavier than 1700lbs, unless you have a hydraulic clutch system and Arnold Schwarzenegger's left thigh. Other than that, the choice is yours. There is a centre plate called a ProGrip, I have just fitted one to a 2 litre I have just built, it feels like a standard plate, but appears to stick very well considering it have a standard pressure plate.

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Running for the first time

Complete 2 litre All right, so you've built your dream engine. Don't destroy it before you have used it. If you have replaced most parts of the engine, and of course, you used an air line to blow out all the oil galleries to make sure they were open, there will be no oil in your engine. You can, before you fit the oil cooler, using a small funnel, pour oil into the hole nearest the pulley wheel end. It will take quite some time to pass down the line, but if you turn the engine over backwards by hand this will help pull the oil down. Put about 1 pint/half a litre down into the engine, then fill it up normally (through that silly little, offset pipe). Use a good oil, and once you have filled it up and fully assembled the engine, connect it all up, all except the positive supply to the coil. The idea here is that you don't want the engine to fire up, just yet.
Turn the engine over with your foot hard down on the accelerator pedal and until a short while after the oil light goes out (about the count of 5). Now the oil has passed through the engine you can connect the coil. This time pump the accelerator twice and leave it alone (until the engine fires), turn on the ignition and fire the animal up, but do remember what it said on the instructions that came with the cam.
Right, now go and show those Ford owners what a Bug can do.

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Useful data

Calculations and useful numbers:

Calculate CC: Bore X Bore X Stroke X 0.0031416
Calculate cylinder CC: (Bore X Bore X Stroke X 0.0031416) divided by 4
Deck height CC: (Bore X Bore X Deck height in mm X 0.0031416) divided by 4
Head CC: using a measuring jug (one in c.c.s and in single units) fill it with 100 c.c.s of a liquid (I use ATF 'cos it's red, but you can use anything that is easy to see) put the head in a vice with the bottom of the valves facing upwards (you will need both valves and a spark plug in), make sure it is level and pour in your liquid until it is level with the surface where the cylinder mates with the head, once there you know how much fluid it took to fill it up.
Compression ratio: (Cylinder CC + Deck height CC + Head CC) divided by (Deck height CC + Head CC)
Calculate carb size: (Square root of (Cylinder CC X Max RPM)) divided by 40
Calculate Choke size: (Carb size X 40) divided by 50
Calculate Main Jet size: Choke size X 4
Oil temperature: Don't go over 120 degrees C too much

Other data:

To set up a 009 or 050 distributor when using a degreed pulley wheel, make a mark on the 32 degrees before TDC with a felt pen or liquid paper, then run the engine using a strobe light attached, slowly raising the revs, then when the engine is at full advance (you will know when that is as the mark you made stops moving) turn the distributor to move the mark until it lines up with the case centre.

To balance a set of dual carbs is not all that difficult, if you have a carb synchroniser this can be used to measure rather than listening for evenness. Either way, firstly disconnect the linkage to both of the carbs, then screw in both idle adjustment screws in about two turns. If you are going to use a synchroniser, remove the air filters. Now start the engine, it should run relatively high, now by adjusting only one idle screw up and then down until the engine sounds sweet and smooth or measures the same on both sides. Turn off the engine. Reconnect the linkage to both carbs and loosen the adjustments on one side. Now adjust the linkage on that side until both throttle arms rest on their stops. Open the throttle from the cable link (centre of the cross-bar) noting which carb opens first, adjust the linkage to raise or lower that throttle rest and continue until both carbs open together, then tighten the linkage lock nuts and re- fit the air filters. Re-start the engine and unwind the idle screws evenly until you have a nice running engine.
To set up the idle mixture, wind all four screws in gently until they stop, then wind them out about two turns (as long as it is the same on all four carbs). Restart the engine, once it has warmed up it should be running smoothly.

Thanks for reading. I hope it has been useful.

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