Dellorto DRLA 40 Carburretors, Jetting and turbo application.

22nd August 2009

I had always used Weber carburettors in the past and was always hearing that Dellorto carburettors were far superior from people who had used them for years. With my new engine now progressed to the long block, I had to decide how I would supply fuel to it. Previously I had a project that consisted of a Garret turbo T3 unit and a drag exhaust that had been extended to work together. None of this had made it onto an engine and I figure that with the new strong block that I had built this would be the best time to bring it all together. With this in mind I new I could not use Weber carburettors as they could not easily be modded for turbo use. I found two Dellorto DRLA40 carburettors online in an auction that originally were from an Alfasud. I new the jetting would be wrong for the 1600 long block, but I figured that the jetting would all change with the turbo anyway so this would not be a problem. The first thing I had to do was to thoroughly clean the DRLA40's up. This is a fairly large job as it does not just entail cleaning the outside of the carburettors . The inside must be stripped down and cleaned thoroughly too. I decided this was the way I was going as I knew that ultrasonic carburettor cleaning techniques although good, would not find broken or missing parts should there be any. Once the carburettors had been thoroughly de-greased with Gunk, I started to dismantle them. The filter covers are bolted to the top of the carburettors, with this removed the top of the carburettors can be seen and access is then available to remove the top screws that hold the two parts of the carburetor together. It is beneficial as well to photograph the components before removing them so that you can easily remember were they go when rebuilding. The top will then come off the carburetor and will take with it the float which is attached to the roof of the carburetor.

I contacted John Maher Racing Ltd ; Mr John Maher in the Outer Hebrides, The isle of Harris. http://www.johnmaherracing.co.uk to ask him if he still could machine the pair of DRLA carburettors for turbo spindle seals. He told me that he still had the equipment to do this but he also said that he could not covert all Dellorto carburettors. He went on to say that you needed a 20mm boss inside the middle of the carburetor to give enough room to take the turbo seals.

He indicated that he had seen carburettors in the past that did not have this and could not be converted. Luckily my carburettors were OK and I sent them of to him. You can see the boss on the inside of the carburettor wall clearly. the picture also shows that unlike the outer bearing which is sealed. the throttle shaft runs straight onto the crab bodywork meaning that the surfaces had no seals to keep fuel in the carburettors under more than atmospheric pressure. The carburettors throttle shafts have to be routed out with a special tool that allows one side of the carburettor body to be done at a time. The picture right show the process of cutting the turbo seals. This is repeated three times for each side as three steps must be cut into the body to allow a plastic washer, o-ring and star washer to be fitted. The whole process is done from the outside of the carburetor with a cutting tool mounted on a spindle that is passed through the existing throttle shaft-hole. The cutter is also supported on the shoulder of the other side of the shaft. Some cutters have a cutting surface on each side. This actually allows the process to be simplified by pushing in and pulling out to do each of the bosses. It is imperative the recesses that are cut true to the throttle shaft .

The picture left shows the machined boss ready to take the turbo washers. It shows the three cuts made into the sidewall of the carburetor. I used the specialist services of John Mayer as I felt that he had the tools to do the job correctly. Obviously this is a risky modification to a carburetor as if the seal leaked then your whole engine could go up in flames very quickly. I ordered my turbo seal kit from Euro Carb http://www.dellorto.com and waited for my carburettors to be returned to me.

My carburettors came back very quickly and I was very happy with the machine work that had been done. I previously had stripped out everything but the throttle body as I wanted to keep the machine costs down. I knew I just had to rebuild the carburettors and had taken some good photographs of the carburettors in various states of being dismantled. The first job was to fit the new turbo seals into the newly machined areas. This seemed at first an easy job as it required fitting the washer and the o-ring followed by the star washer which was pressed into the recess to hold the washer and o-ring in place. My first attempts at this resulted in the star washer pinging back out. I decided that I would use the throttle spindle to line up the washer and o-ring so that the star washer could be pressed into place. I also used a small pair of pliers around the spindle to press the star washer from opposing sides. My patience was soon rewarded and I manged to get the four seals in place and the throttle spindle back in the carburettor with the ball race seal at each end. It is very important when assembling the throttle to match the spindle to the right carburettor side, as the spindle protrudes more on one side to accommodate the levers for the linkage system.

The butterflies could then be fixed to the throttle spindle again paying attention to the way they came out. It is important to put these in carefully as they will not fit if forced and they are very easy to bend. The rest of the carburettors could then be built up . The accelerator pumps were renewed and fitted back in. The other ancillary items where added to the carburettor and all the components where cleaned and assembled as can be seen photograph left:


At this point I had to decide what I was going to do about jetting. Fortunately I had met a gentleman Dan on Volkszone who had turboed his Beetle . He suggested that I should start off with the jetting he had as the cars had a similar specification as he had had his carburettors professionally set up. I bought the turbo conversion kits as they came with the turbo gasket and the high capacity needle valve for the float bowl.



DRLA 40 Aspirated jetting
---------------------------------

• 4x Venturis 28mm
• 4 x Main Jets  1.20
• 4 x Air corrector  1.8
• 4 x Idle jets 7644  .6
• 2 x Pump Jet 0.35
• 2 x Needle Inlet 1.5
• 2x starter emulsion tubes 7482.3
• 2x Starter Jet 60
• 4 x Emulsion tube 7212.2

DRLA 40 Turbo jetting
------------------------

• 4 x Main Jets 160
• 4 x Idle Jets 7644.60
• 4 x DRLA Pump Jet 10927 not DHLA 10927.
• 4 x Turbo Emulsion tubes 9164.turbo
• 2x starter emulsion tubes 7482.3
• 2 x starter jet 3315.80
• 2 x Air Corrector (short) 7482.170

This was quite a shopping list as the jets and emulsion tubes are only available from a few outlets. Luckily I found some CB Emulsion tubes on eBay that were better than the standard ones. I also found main jets , Idle jets an air corrector from a dealer on eBay: Fast RoadCars. The rest I would have to buy from Euro Carb. It is important to note that some parts can be shared between the DHLA and the DRLA with jets . The exception to this though is the pump jets 10927 which the DRLA uses longer versions than the DHLA.

I was very surprised how expensive the jets and the turbo conversion had cost. In hind sight It would have been cheaper to have bought one already modified but then I don't think I have seen many on the market for sale as in recent times there has been a drive towards efficiency and the carburettor has been surpassed by the injection system. This said the injection system is a whole lot more complicated and I was intending to cut my teeth on a turbo system that had a smaller number of parts to go wrong.

If you are considering doing this conversion to a set of carburettors budget at least £80-£100 for the DRLA 40 carburettors, the machining will cost upwards of £69.00 depending on how they are delivered to JMR, Turbo Conversion gaskets, seals, pump valves and other ancillaries around £96.00 without the re-jetting costs which if you may be able to source the parts from other suppliers.

I would have to purchase a new CB linkage kit for the carburettors as I knew that the CB pressure covers only fitted the CB linkage kit.

Prices current 2009 only.

Rockers, Setting up valve adjustment.

12th August 2009

I decided that as there was a good possibility that the 1600 TP engine I was building would go turbo that I would be best to buy some bolt up camshafts . Luckily I found some bolt-up shafts with standard ratio's and elephant feet already fitted. Generally as you can see they were in very good condition and needed little work before fitting. I had hoped that the rockers were the needle valve version but unfortunately this turned out not to be the case. I fitted the rockers onto the heads and torqued up the bolts to 18 ft/lbs or 24 Nm. The engine was then left overnight to allow the rockers to come down to the temperature of the engine.

With certain high performance rockers it may be necessary to use shims under the rockers additionally be sure your rockers are shimmed properly on their shafts most rockers come with a selection of shim sizes, To check your rockers are shimmed correctly on their shaft and assuming you are running solid shafts, think of the rocker assembly as three distinct sections separated by the two rocker arms. Each of these sections should be shimmed to about .004" side clearance.

This is really easy to check with a set of feeler gauges. You can move the rockers side-to-side depending on where you put your shims. You should try to aim the rocker for the centre of the valve stem with ball type and elephant foot type adjusters on stock style rockers as well. For wiper and roller style rockers, try to get the pad/roller to be centered on the valve stem.

If you are still using stock adjusters, then aim for slightly to the left of centre on the valve stem; this will help the valve to spin slightly during operation. A very neat trick keeping the valve seat clean.

If you're using 1.4 or higher ratio rockers, you may need to start with a .060" shim under the rocker bases or you'll experience coil binding that you shouldn't be seeing. You will also certainly need to check the length of your push rods.

In my case because my rockers were using elephant foot adjusters this takes up a portion of the adjustment room that requires either shorter push rods or more shims to pack the rockers out. I managed to find enough room using two 0.60" shims that enabled enough adjustment at the rocker . The other option would have been to have ordered some cut to length push rod tubes these retail at about £50.00 and I did not want to go down this route just yet. It is also important to note that the elephant foot ball adjusters have a flat spot on them that has to be orientated onto the valve head before fitting so that the flat side rests up against the valve top.

It is very important when adjusting valves to ensure that the whole assembly is below 50 degrees Centigrade. The valve adjustment is the most important setting that can be adjusted in a V.W beetle engine because the valve adjustments are critical say for example if an exhaust valve is tight on #3 cylinder that sits behind the cooler then the oil gets hot as only three cylinders are working hard. When the oil gets hot it is inadequate to lubricate the connecting rods and they can eventually fail loosing a piston or just locking up your engine. Setting the valve adjustment is a simple task that can be completed by anyone with the correct tools at home and generally is better done at home as most garages use blowers to bring the temperature down, which is not nearly sufficient as an engine can give tighter settings if warmer than what you can achieve by leaving your car alone overnight.

One of the most important things about valve adjustment is finding the correct valve settings for your heads. Generally speaking I think it is most accepted now that 0.06" is the best setting for both inlet and outlet valve clearance. In my experience this is good for most modern heads Although this has been discussed vehemently in the past by checking for long or short rocker studs and can vary on the inlet and exhaust port to inlet 0.04" and exhaust 0.06" respectively. It has also been discussed that 40hp engines have long studs and should be set to 0.08" for the intake and 0.12" for the exhaust. Furthermore if you have an early 1500 engine and long studs, both should be set to 0.12" .Additionally if you have Chromoly push rods you should set both inlet and exhaust to .003".  Should you have steel Push rods then you will need to set both your inlet and exhaust to 0.02".

Once you have decided on the inlet and outlet adjustments that you want to use. You need to park your car up out of gear and chocked the night before where it can be accessed at the back from both sides of the car. Do not jack it up. You then need to also familiarize yourself with the parts of the engine. You need to know where each of the cylinders are, the rocker covers, pulley wheel and spark plugs. You also need to assemble a small tool kit. For this you need a 13mm spanner a good quality wide flat blade screwdriver, a large socket 30 mm and a wrench bar, Spark plug wrench and feeler gauges (metric or imperial). You also need to acquire new cork or rubber rocker cover gaskets.

The next day you are ready to start. Your car has cooled sufficiently to allow you to start setting the valve adjustments. The first thing you need to do is to find Top-Dead-Centre. This is usually where people go wrong as their instincts tell them to go and look at the distributer and look for #1 cylinder lead. This is not always a good accurate method of finding TDC as your engine could have just been rebuilt or the distribute could have been removed for another reason. Ensure the ignition is off and the car is out of gear.

To determine TDC (Top-Dead-Centre) you must find the point were the engine revolves and compresses the gas on the #1 cylinder . Remove the distributor cap and check to see if there is a mark on the distributor body. Place the 30mm socket on the pulley and rotate the engine clockwise until the rotor arm points to this mark. Check to see if your mark on the pulley is in line with this or 7.5-15 degrees away. Move your pulley wheel to TDC. With your engine set theoretically you should have no #1 firing position but we want to check this. Start by locating #1 cylinder examine it carefully and remove the spark plug wire from the end of it and remove it with a spark plug wrench. With the spark plug removed you can use a thin piece of wood to measure how far the piston is down the cylinder . Ensure your piece of wood is solid and is thick enough not to brake. A paint brush handle from an artist brush is a good choice. Place the 30mm wrench on to the pulley and start turning the engine over by hand in a clockwise direction and then anti clockwise. Your ignition must be turned off as you rotate the engine. Test how far the piece of wood goes into #1 you should see it rise and fall as you rotate the engine left and right you can narrow this down to find the highest point the piece of wood sticks out. This is actual TDC and should have placed your notch on your pulley at 12' o 'clock.

With the location of TDC acquired you need to remove the rocker covers place an old rag below the rocker cover to catch any oil. There are two types of rocker cover fixings a bolt on type with 13mm bolts or a spring system. If you have the lever spring system use a screwdriver to lever off the the spring clip.

Sit on the floor next to #1 cylinder and look at the area you have uncovered . You will see four rockers that are sitting on a horizontal shaft. At one end of each rocker there is a cup that locates the push rod, and at the other a screw adjustment that sits on top of the valve spring assembly for each cylinder. The two rockers that are nearest the front of the car on the drivers side control no#1 cylinder. The two further back control cylinder #2. On the opposite side of the car the two nearest the front of the car control cylinder #3 and the remaining two are for cylinder #4. The rockers that are furthest out from the middle and are at opposing ends of the shaft are the exhaust port rockers. The two inner rockers control the inlet valves.

With #1 cylinders inlet and outlet rockers located find your feeler gauge and select the blades to make up the size of the adjustment you are going to use in my case 0.06". Push the tail end of the exhaust rocker arm down so that it swivels down towards the push rod. Try the blades you selected of the feeler gauge in the gap between the adjuster screw and the top of the valve head. It should just fit and you should feel it drag as it pulls through the gap between the rocker and valve top. If it does not feel like this or it feels stiff or will not fit you need to adjust this valve. The rocker adjustment is a machine screw with a locking nut. You need to use the 13mm spanner to undo the locking nut. With the locking nut removed you can undo the screw with a screwdriver to create more gap anti clockwise or clockwise to reduce the gap. There are two ways of setting the gap one is by trial and error the other which I favour is the entrapment method.This consist of trapping the blade between the screw of the adjuster and the valve head. Once you have the blade trapped the screw can be held with a screwdriver whilst the locking nut is done up. This can take several attempts to get it right. When you have made the adjustment and are satisfied with the setting ensure the locking nut is tightened adequately before repeating the same procedure with the inlet valve. With both valves set for #1 cylinder you need to move the engine counter-clockwise 180 degrees 1/2 the circle of the pulley or the BDC (Bottom Dead Centre)mark. Once you have rotated the engine you can adjust the valves for #2 cylinder as described above remembering that the valves are a mirror image of #1's cylinder with the inlet towards the front of the car and the exhaust valve at the rear. Once complete the engine is rotated 180 degrees 1/2 a circle of the pulley wheel TDC so that the adjustments can be made on cylinder #3. Remember this is similar to #1 cylinder and the exhaust port is the one nearest the front of the car. Once completed finally the engine can be rotated for the last time 180 degrees or 1/2 a circle of the pulley and BDC and #4 cylinder valves can be adjusted. The exhaust port is again the one nearest the back of the car.

When you have adjusted all four cylinders sit back and admire your handywork. You can replace the valve covers ensuring to renew the cork/rubber gasket.

Rebuilding the 1600 long block

1st August 2009

The small block I started last month seemed to be a distant memory as personal changes in my life were at the fore of my mind and I was finding difficulties in locating the parts I needed for the long block.

I had sourced the 1600 barrels from a very good friend in return for a bottom end rebuild he wanted me to do for him. I negotiated that it would be better if I told him how to do it, so I was going to show him when he was ready to get it done and hopeful pass on some lessons I had learnt on my first rebuild.

The Barrels were in reasonable condition for their age

with three of the pistons in good condition with the third showing some significant mark on the surface. I decided this would have to be replaced and placed a thread on Vzi to locate a replacement . I cleaned the barrels up using a degreaser gunk and then with a wire brush. I used 600F degree VHT black paint to paint them. The barrels seemed easy to find unlike the Marle piston rings that seem to be disappearing sadly from the shelves of GSF and many other VW suppliers. I hope this is just a problem with the import and does not mean we are losing them as I still favour Marle above other makes. You can see pictured right I have checked the alignment arrows on the piston surface that face the flywheel and placed a circlip pin in the same end so that I could not mistake the direction that the gudgeon pin had to be driven in. I eventually found some Marle piston rings and started to fit them to the pistons. Generally this is much easier to do if the piston is covered in oil. The packet of rings is normally divided into three sections with the rings for the bottom middle and top slot all held together. Starting with the bottom ring position nearest the connecting rod. The correct ring can be identified easily as its the widest one and usually consists of a spring device or frame, cover two separate side rings or a frame that fits over the spring frame. I have seen both types of bottom ring oil seal in Marle kits so it is good to be familiar with the different types. My Marle kit contained the undulating frame and two separate rings The undulating frame is colour coded to allow it to be correctly placed together. Personally I think it is better to fit it and try overlapping either way to ensure that its profile fits nicely together. The two thin rings sit either side of this to ensure a good oil seal. The undulating frame keeps them separated and sprung. The next ring up is a much larger ring and you must be careful to get it the correct way up by finding top marked on it. This can be slid over the piston crown in much the same way the other thinner oil rings were introduced. More care must be used though as its large size makes it more brittle. The top ring is also marked on one side 'top' be sure to also get the orientation of this ring correct. Slipping it onto the piston in the same manner used before. With all three rings on the piston great care must be used to ensure the gaps in the rings do not line up. Generally speaking I put these at 90 degrees to each other so that no gas could escape past them. The ring assembly procedure is then repeated for the other four pistons.

With the rings in place you can insert the pistons into the barrels I have tried many home made devices to fit the pistons in but to be honest they do not work as well as the piston ring compression tools that are on the market and can be bought for as little as £10.00. The only disadvantage of these cheaper ring compressors is that you have to remove the gudgeon pin to take the ring compressor on and off. With this in mind the piston ring compression tool can be slid onto the piston and the ratchet then ratcheted up to pull tight against the rings. It is important at this point to ensure that the piston ring compression tool fits around the piston with the top of the piston flush with the skirt of the piston ring tool. Also if the piston ring tool is made of spring steel rings ensure all the rings are flush. Lubricate the bore of your cylinder. Place the piston upside down on the neck of the barrel. With a piece of wo0d placed inside the crown of the piston, knock the piece of wood , whilst holding the piston ring compression tool and piston centrally over the barrel. A few short taps should place the piston in the barrel. Make sure the skirt of the piston is protruding from the barrel so that you can re-insert the gudgeon pin.

The barrels can be then placed on to the engine block. You must start with the cylinders nearest the flywheel end of the engine. If you tap the gudgeon pin so that it slightly protrudes inside the piston, you can locate the gudgeon pin in top of the con-rod. so that it can then be tapped home with a round drift like a socket extension so that it sits comfortably against the clip. Place the clip in the end of the piston to secure the gudgeon pin taking care not to spring it inside the engine. A piece of cloth can be draped over the engine apertures to ensure this does not happen as a complete rebuild is needed to remove it!. With the two barrels nearest the flywheel in place the other two barrels can be placed in the same manner remembering the securing clips for each. As you work putting the barrels on you may need to rotate the engine to get the con rod out far enough to make the connection to the piston. With all the barrels on the short block tap them with a mallet so they sit firmly in the case. Fit the air deflectors to the underneath of the barrels - these clip in between the barrels and fit on the bottom of the barrels blocking the air flow from pushing straight past the barrels.

With the barrels and pistons sourced and fitted I was left with the task of finding some 1600 heads. The answer again came from a friend Huw from vZi who drove them down to me. It was very nice to meet him face to face. When buying replacement heads it is important to check that the heads have no cracks in them. The spark plug areas are notorious for this and need cleaning to ensure they are crack free. Also check the fins are intact and the threaded areas are good and not stripped. The heads were in very good condition and did not take much cleaning to bring them up to good condition. You can see pic right that they didn't look like they had more than 500 miles on them as they still carried the lustre of new heads. I cleaned them down with spray-on-Gunk rinsed with my favourite garages jet wash. This was particularly funny as it was tipping down with rain and instead of getting wet from the jet wash I was soaked from the rain too I must have looked comical. Once I had them back I covered them with carburetor cleaner and wiped the remaining residue off with a cloth. I left them to dry before assembling. I was very pleased with the heads after cleaning them up. I removed the tired exhaust studs from the heads as I always think it is fool hardy not to as they are very inexpensive to buy. They can be removed by locking two nuts onto each other on the stud and undoing the lower nut. This process will remove most studs but invariably there is always one or to that you need to apply heat to so that they will start to move.

Before installing your heads you should check that you have the correct fitting kit. Some heads need a copper washer to be fitted but others like my 1600 heads require a straight fit. You also need to gather the push rod tubes push rod seals and push rods as you will need all of these to fit the heads onto the barrels. Personally I always use new and fit the seals onto the tubes with grease up front to fitting on the heads. You should firstly fit your heads as a trial fit to ensure they go onto the studs and fit snugly onto the cylinder heads. If you are using older heads then it is better to grind the heads to fit the barrels. This can be achieved by using valve grinding paste on the surface of the barrel and rotating it in the head until it finds a flat seating. If you have to grind your heads ensure both parts are cleaned thoroughly to remove the valve grinding paste (Very important.).

The head install is a four handed job that requires a balancing act of the push rods and the heads. Personally I start with the head placed onto the studs. After greasing the ends of the push rod tube I then place each push rod tube in situ. I use the push rod to poke through the tube so that the tube is supported and does not fall out and is held on the push rod this is repeated for one side four in total. With everything in position you can try to slide the head into its final position as you do this keep an eye on the push rod tubes and ensure that they stay seated into the concave recess or the engine case and head. Once you have the head on far enough you can use two of the nuts to wind it in further checking again that you have not trapped the push rod tubes. You can now start to torque up the heads. This needs to be done in a precise order so that the heads are pulled on evenly to the barrels. Start by torquing the nuts up to 7ft/lbs or 9.0 NM ensure you have a washer behind the nut follow the 7ft/lbs diagram (Far left) in order to tighten the bolts in sequence. Once you have torqued up the nuts change the setting on the torque wrench to 23ft/lbs or 31 NM and re-torque the bolts in the order of the 23ft/lbs diagram (far right above) Note there are two different sequences for tightening the heads this is important. During this process check that the push rod tubes have not moved and are seated properly. This procedure must be repeated for the other cylinder head.

The end float must then be calculated for the crankshaft to allow the flywheel to be fitted. The tolerance for this needs to be between 0.07" and .012". It is generally easier to do this with the front pulley wheel removed. Both the the mating surfaces on the flywheel and the crankshaft must be thou roughly cleaned. You must then ascertain whether you need a paper , metal gasket or o-ring seal and no gasket. I was using a 200mm later flywheel with an o-ring that used no gasket and just needed the o-ring replaced. With this done check the dowel pins in the end of the crank are good and straight and load the flywheel onto the end of the crank. Be careful you may need to support it with a block of wood as it is fairly heavy. You then need to pull the flywheel onto the crankshaft tighten the flywheel nut and torque it up as high as your torque wrench will go. With this done you can start to get a feel for how much end float you are dealing with by pulling in and pulling out the flywheel to see the extent of this movement. To measure this you either need a DTI and magnetic support arm or a vernier gauge with a dial indicator on it to improve its resolution. The vernier gauge has a depth gauge on the lower half of the gauge and it can be used to measure from the surface of the flywheel to the engine case. Start with the flywheel pushed back towards the back of the car as far as it goes. Use the DTI or vernier to measure this distance. Pull on the flywheel as far as you can get it out measure again from the surface of the flywheel to the case. Subtracting these figures will give you the gap that your flywheel moves. This will need to be packed with three shims that will reduce this gab to the correct tolerance . Shims are available in 0.24", 0.30", 0.32", 0.34" and 0.36" only. Select three shims that give a total width that when subtracted from your gap brings the end float back into tolerance as near as .07" as you can get it. Once you have the three shims remove the fly wheel and place the shims on the crankshaft. Replace the flywheel and test to see that you have good end float. When you are finally happy remove the flywheel and fit the fly wheel oil seal into the case. This may need to be driven into the case with a block of wood. refit the flywheel and torque it up to 230 ft/lbs.

Once this has been completed your long block is complete. The only exception being the rockers and valve covers both will be covered fully in the next article.

Parts Used.
-------------
FREE Barrels & Pistons.
£10-15 1 x Replacement Second Hand Marle 85.5mm piston.
£120-£150 per pair Second hand 1600 cylinder heads.
£20 - £25 - Marle 85.5 mm piston rings.
£10 Piston ring compression tool.
£20 Push Rod Tubes and seals.
£10-15 Engine Gasket set.

N.B All Prices included as a illustrative guide only.

Engine small block rebuild

30th June 2009
The idea of rebuilding the bearings of a beetle engine to most people is something best left to the technical amongst us. To be honest this may be true as you get a more accurately built engine , however it is not something that cannot be done in your own garden shed.

Principally the hardest part of rebuilding an engine is changing the main bearings. There are many problems with this as cases are sometimes line bored to accept slightly larger bearings. With this in mind you must be sure which bearing set you need to order. Most good suppliers are only to helpful with this and armed with the correct bearings and your bearing saddles not having any strange grooves or lumps out of them then you can fit the bearings as detailed below. If the bearing saddles are pitted , scored or otherwise trashed you will need a line bore through the bearing saddles so that the bearings can be seated properly. Generally speaking if you are having a line bore its best to order the bearings through the company doing the line bore to ensure you have the correct ones.

The next problem most people encounter is to remove the bearing that sits between the camshaft drive and the number 2 rod shoulder. This is something I have always had done in the shop but to be honest its not as difficult to remove as you would think. To remove the bearing you will need either a three pronged puller or a proper crankshaft bearing puller which unfortunately are fairly expensive. The other thing you will need is plenty of heat , now we are not talking about a paint stripping gun. We are talking about a butane torch that will heat the bearings up to a temperature that they will expand enough to slip of the crank shaft. When you have both of these you can remove the oil slinger by removing the wood ruff key with a screwdriver and hammer to tap it out this will give access to remove the circlip use a screw driver to prise the circlip of the end of the crank. The bearings can then be heated and heated some more until they are hot enough to enable the puller to pull the camshaft gear and distributor gear off. Be careful when they are off as they will still be very hot.

With the camshaft drive off you can slide the old bearing of the crankshaft. You need to check the bearing surface for any defects. Now putting them back is not the same procedure as taking them off. Ensure that you put the new bearing on with some bearing compound such as Joe Gibbs Assembly lube grease, which will help bed the bearing in. The next important thing much overlooked is to ensure the camshaft bearing goes back on with the two dots facing towards the end of the crank. The curved in side of the drive needs to go next to the bearing. Now to get the drive back onto the crank you will need to heat up the camshaft drive again. The easiest way of doing this is to pop down to Tesco and buy a cheap saucepan and fill it with engine oil and put both on a camping stove. Watch for bubbles appearing from the drive. When you get this the drive is hot enough to be dropped back onto the crankshaft. Be warned get it the right way round! Also don't go hotter or you will set the oil on fire. Fit the racer spacer next and then use the same process to heat up and fit the distributor drive. Finally the circlip can be replaced. The oil slinger must then be placed back onto the crankshaft it may be necessary to remove the pulley wheels wood ruff key to enable to fit the slinger the concave side must face outwards.The other bearings can then be lubed up and placed on to the crankshaft bearings with the exception of the middle one which must be fitted to the case.

Personally I did not fit my crankshaft at this point but instead checked the play in the con rods which in my case was considerable. The tolerance for measure this is done by inserting a feeler gauge down the side of the con rod. There should be no more than 0.016-inch min by axial measurement. The bearings can be bought for very cheaply and can make a considerable difference if the crankshaft saddles are in good condition. Ensure that you remove and re fit the con rods the same way up. All the notches should face up and the con rod marks should appear the same side for the top as for the bottom. The con rod bolts need to be torqued up to 23lbs. The new bearings made an impressive difference remember to lube them in using the same pre-assembly lube as the crankshaft. With the rod bearings fitted the crankshaft can be fitted on to the bearing saddles. remember to check the dowels are in situe and are in good condition. The bearing need to be aligned so that they fit onto the dowels and the crankshaft will drop into place.

I decided that I wanted to fit a higher lift camshaft to the engine and had previously chosen an Engle W110 for this engine. I used a Billet Alloy camshaft gear that I had from a previous test comparison. This had been balanced on a lathe as its original casting was poor. The camshaft and drive can be fitted after the cam followers have been lubed and inserted into the case. Ensure that the top of the cam followers have also been lubed. the camshaft bearings are press fitted into the casing on both halves. The larger shouldered bearing fits nearest the drive and the bearing decrease in size towards the flywheel. The camshaft needs to be meshed against the Camshaft . The two dots on the drive gear should nestle neatly either side of the dot that is on the cam gear. This is the correct synchronisation of the two gears and is vital for the timing of the engine.

The two half's of the crankcase can be mated to test for binding on the crank. If the crankshaft is free and able to be moved the two half's can be separated and the camshaft seal can be glued with sealant into the case. I used blue hymelar as a case sealant as it stays tacky whilst your assembling. The six central nuts can be tighten remember to diagonally tighten down. Check the crankshaft can still move by placing the front pulley wheel in situe and then place the peripheral nuts and bolts around the case.


The oil pump can then be fitted into the case a soft rubbermallet can be used to push the oil pump into place. YOu must remove the gears before doing this as they need to be keyed into the camshaft. With the oil pump in place the small block is almost complete rebuild was almost complete. I needed to purchase a full flow oil pump cover as I had decided to go full flow.

AS41 Magnesium Alloy Case Welding the tricks

23rd June 2009
The Magnesium/Aluminium case design of the AS41 case i renown for being one of the lightest design engine cases even by today's standards. This was the brilliant invention of the VW factories in Germany who originally built the engine to power planes. The downside of this design is that the Magnesium/Aluminium alloy was a mixture that was hard to weld. The obvious risk of this being igniting the Magnesium whilst welding so that the hole part you were welding burned with a large flash eating away its form. Traditionally welding these materials takes a great deal of experience as the welder needs to be aware of the composition and must apply only enough heat to weld and not combust. It is also paramount that you have a hammer with you available to beat the crap out of the area you are welding so as to knock the burning magnesium out of the area. The downside of this is that i can leave a larger hole than you start with. Crucial to the weld is also the composition of rod that you use and traditionally the flame is better controlled by a tig welder. Most people believe wrongly you need an Aluminium rod with a Magnesium content to weld the AS41 case. The result of this I found out quite quickly was not the answer and the shop that I asked to weld the case up produced the hole filled and taped but not surprisingly the plug they had welded in did not bond to the case and was simply able to be pulled out.

The correct welding rods to weld an AS41 case are in fact Magnesium rods with a low percentage of Aluminium. The actual percentage being 8% Aluminium to 92% Magnesium. These are available from Armour supplies Ltd in Hastings, East Sussex UK .

Withe the case welded so that the main gantry was plugged I was able to get the case re taped with the 3/8" NPT tap. I used a workshop for this and had to remove all the engine main studs so that it could be mounted in their mill. you can see from the photograph that I decided to have the area made bigger so that the thread had a good fetch into the casing.

The finished plug looks stronger and more durable than the original. I am very suprised this can be done and it blows a large rasberry in the faces of everyone that says it cannot be done or to put it a better way the people that have kept this a secret from us for a long time are now all aware we all know,. I look forward to seeing a lot more cases re welded in the future.

As the answer is a vertible YES!!!!!!!!!!!!!!!!!!!!

Fan housing design and overturning traditional ideas

14th June 2009
With the disaster of my engine case I had to find a company that could weld and re tap the oil gantry. This was a difficult task and in the meantime I turned my attention to the other parts of the engine that needed cleaning up. I had two companies that I had approached to do the case work but both were taking time to come back to me.

Originally I had thought that I would just cut weld and chop of the air outlets from the fan housing but a friend had put a thread on Volkszone about this and surprisingly there had been some technical testing done by Jake Raby's research into engine temperatures and fan housing design. That indicated that the Fan housing design was constructed to have integral vanes that directed the air flow inside the housing separating air flow from the engine and diverting it to the housing outlets. It appeared from the discussions that the general consensus including my own that simply blocking of the vents would cause air flow turbulence in the coursing that would effect the fan housings overall ability to cool the engine.

I have included a picture of the internals of the VW fan housing courtesy of www.offroad.net which is also a source for the information here in comparison. The scat housing picture courtesy www.newlancsvwclub.co.uk is definitely missing some of the internal vanes and although seems to produce adequate cooling there must be reasons why VW included the extra vanes in the first place. The solution suggested by newlancsvwclub seemed to be to cut the whole outer edge of the fan housing down to remove the air channel that would cause the air buffer. This in practise was a very easy option and the rough shape can be seen on the following picture. The internal structure of the fan housing that directs the air to the vents can be un tacked from the fan housing and pulled out to make a new curve that follows the new line of the housing as detailed by the green line.

I started on my fan housing removing first the air outlets with an angle grinder and thin cutting disk. The outlets came of fairly easily and from the holes that were left I was able to see the internal vane that was going to become the outside of the new housing. It is important to leave about 2" of metal at the top of the housing to keep the two halves held together in the correct alignment. With a flexible ruler I marked a line on the outside of the housing. With one side cut away the front side could be trimmed to ensure it was closer to to the vane. The rear section was then cut away and the vane pulled out to meet the new curve. It can be seen from the picture that the vanes do not meet the top of the fan housing. I cut pieces from the cutoffs to make material to fill these gaps. Obviously you could bend the internal vanes to make any new shape you desired, however I was attempting to get the best cooling possible from the design and though that the curved top lended itself to this application.

With the design and metal work cut and established the fan housing needed to be welded up . This is not as easy as it looks as the thin tin ware is quite thin. I used a MiG welder to tack up the housing at opposing points around its perimeter . This gave the construction a better stiffness that allowed the perimeter to be tacked up. The result of he welding process is not as neat as the original design and it as obvious that I would need to prep the housing before painting. After Angle grinding the surplus weld of the housing I decided to try p38 filler to smooth the outline. Discussions with a friend regarding this pointed out that the files likely to chip off from the housing during its use and that I would be better to have the outside prepared by fibre glass. I took the fan housing to a Friend Ash who created a mold from the housing and re profiled it to make a better curve. This was then bonded on and the whole housing was painted and primered. I painted the rest of the tin wear in primer and needed to get a nice cool day to buy some 2pac in spray cans so that all the tin wear could be blacked up . The tin ware was looking excellent and I needed now to get the case repaired. This was looking very interesting as most posts found on Volkszone said it was a potrntial arsonists or pyrotechnics dream come true as the Magnesium base AS41 case just would turn into a large roman candle. Was it going to be possible or was I just going to have to purchase another case or complete engine?


Some pictures courtesy of www.newlancsvwclub.co.u and www.offroad.net.