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.
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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.