Top-End Assembly

 

    This page covers the top-end assembly.  The "top-end" refers to the parts from the short-block out to the valve covers and everything in between.  This page will only cover the assembly through the head torque sequence.  To be ready for this final assembly, you should have already built your short-block, checked deck height as well as calculated and adjusted (if necessary) the CR for your engine.

    One thing that must be stated up front is that when installing your cylinders to the short-block, the assembly CAN NOT be interrupted once started.  The reason, is that you CAN NOT allow the RTV sealant that you use to seal the bottom (ONLY) of the cylinders, to dry prior to torqueing the heads.  So before you begin either side, ensure you have all your parts ready, easily accessible and be sure that you have enough time to finish this prior to heading out on that hot date.  If you don't think you have enough time, don't start.  Or, do the right thing,. . . and make her WAIT!! :-)

    Before we start, let's get all our parts ready to go.  I start by getting all my new pushrod tubes prepped.  The bellows on both ends, should be slightly stretched by using your thumb.  Note the difference in size between the stretched tube and the un-prepped tube below.  I also install all the rubber tube seals and pre-wet them with a thin film of oil.  you should always pre-lube rubber seals and o-rings prior to installation.  This helps them get a good clean mating to the part.

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    I then ensure I have all of the proper cylinder shims (silver in color) easily accessible and copper head gaskets (if used) pre installed in the heads.  Installing the head gaskets takes nothing more than carefully pushing them into place in your head's cylinder bore.  Be VERY careful not to bend or otherwise damage them during installation as damage could affect the seal.  NOTE: Copper head gaskets are NOT a requirement.  Your VW did NOT come from the factory with them.  I am installing them so that I can take advantage of the superior combustion chamber sealing that you can get with their use.  Also ensure that your head washers and bolts are readily accessible. 

cyl-shims-head-gaskets.jpg (35309 bytes)             copper-head-gasket-install.jpg (54015 bytes) 

    Now it's time to install the pistons into the cylinders.  This next step is one that I do differently than anyone else I've seen.  Everyone else will install the pistons onto the connecting rods and THEN compress the rings and slide the cylinders on.  I prefer to get everything assembled prior to installing the pistons to the connecting rods.  I've found it MUCH easier to work with the ring compressor off the engine and have found no drawbacks with my method.

    You should thoroughly clean the cylinder bores and pistons with soap and water to remove all honing debris as well as remove the cosmoline preservative.  You then need to pre oil the cylinder walls with oil.  I like to use a paper towel wetted with motor oil to pre oil them.  

    Assemble your piston's rings as per your pistons instructions.  Then I note the direction of the arrows on two of the pistons and arrange them pointing toward the flywheel end of the motor.  I arrange the piston ring gaps so that NO RING GAPS ARE AT THE BOTTOM OF THE PISTON and all are 90 - 180 degrees apart.  I always place the two bottom oil control rings with their gaps at about 10 & 2 o'clock position and the two upper rings at the 4 & 8 o'clock positions.

    I then place the compress the rings with the special ring compressor leaving a small space on the top to place them into the bottom of the cylinders.  Then I push the piston down into the cylinder bore just to the top of the wristpin bore.  Install the INNER wristpin clips (the clips that are at between the two pistons. 

ring-compressor-tool.jpg (37767 bytes)             compress-rings1.jpg (30518 bytes)             ring-compressing2.jpg (44518 bytes)             cyl-ready.jpg (43476 bytes)             cyl-ready-arrows.jpg (42218 bytes)

 

    EVERYTHING BETWEEN THE BELOW TWO LINES NEEDS TO BE DONE WITHOUT TAKING A BREAK OR STOPPING.  STOPPING AND ALLOWING THE SEALANT TO DRY PRIOR TO FULL INSTALLATION, WILL NOT ONLY CAUSE YOUR ENGINE TO LEAK BUT IT WILL ALSO NOT PROVIDE A FLAT SURFACE FOR YOUR CYLINDER TO SEAT TO THE ENGINE CASE.


    Now that your pistons & cylinders are ready now ensure you have the time to finish the next series of steps without stopping.  Installation should take approx. 20 minutes PER SIDE.  Place a bead of high-temp RTV on the bottom of each cylinder.  Then place your cylinder shim(s) (if used) onto the bead of wet RTV. (NOTE: if you are using more than one shim under each cylinder, you will need to seal between EACH SHIM.)  Now add another bead of RTV sealant on top of the shim.  When you have the two cylinders ready for that particular side of the engine, you're ready to install them.

rtv-cyl1.jpg (55826 bytes)             cyl-shim-install.jpg (48262 bytes)             rtv-cyl2.jpg (54151 bytes) 

    Now you can slide the piston/cylinder assembly onto the engine studs.  Push in the wristpin of the first piston and install the remaining wristpin clip.  Ensure that this clip is properly seated in it's groove.  Failure to properly seat the clip will result in the destruction of the piston, cylinder and rings for that cylinder.  Carefully slide the piston down into the cylinder bore of the engine case and seat the cylinder onto the case causing the excess RTV to squeeze out from between the shim(s) and the bottom of the cylinder.  There's no reason to try and wipe up the excess that was squeezed out.  It's fine to just let it harden in place.  Now rotate your crankshaft 180 degrees and repeat on the next cylinder.

wristpin-clip-seated.jpg (47298 bytes)             rtv3.jpg (53097 bytes)

    Before you can install your heads, you MUST install the under cylinder air deflector tin.  There's two different kinds.  The standard type-1 and the type-3 (or "cool tin").  For my engine I opted for the type-3 cool tin.  These snap into place just like the standard tin but they completely surround the bottom half of the cylinders.  I feel it is a superior design but it does have a tendency to not hold onto the studs as well as the standard tin.  I always use safety wire to wire it up in place.

t3-cyl-tin.jpg (41618 bytes)             cyl-tin-safetywire.jpg (53553 bytes)

    Next you will take your prepared head and slide it part-way down.  NOTE: DO NOT USE ANY SEALANT OF ANY KIND ON THE CYLINDER-TO-HEAD MATING SURFACES.  Before you fully seat it you will need to get your pushrod tubes in place.  Work from one side to the other ensuring that the seams in the tubes are UP.  Once the tubes are all in place, gently push the head the rest of the way on ensuring that all the tube seals are properly seated in their respective recesses.  I usually give each tube a little twist & wiggle to ensure they are properly seated.

pr-tube-install1.jpg (40571 bytes)             pr-tube-install2.jpg (41285 bytes)

    Now you'll need to install the head washers and nuts and using the preliminary torque sequence, torque the nuts to 7 ft. lbs.  (Photo courtesy of the Official Robert Bentley service manual.)

head-torque-preliminary.jpg (32699 bytes)

   Then using the final torque sequence, torque them to 18 Ft. lbs (for 8mm studs) OR 23 ft. lbs. (for 10mm studs)  I usually wait an hour and again check the torque.  (Photo courtesy of the Official Robert Bentley service manual.)

head-torque-sequence.jpg (40534 bytes)

    Now you can take a break and admire your good work!!  That wasn't as hard as you thought it would be, was it??

 


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Revised: August 29, 2003 .