Technical Bulletin

[hercdriver]

I'm rebuilding my Type IV 1.7 liter and came across a technical bulletin for 2.0 liter engines.

The bulletin can be found at.... http://www.ratwell.com/mirror/sfraser/techbull.html

I was wandering if this can be used for 1.7/1.8 liter engines. The bulletin does state that it is for 2.0 (engine codes GD, GE, CV), but I thought that the smaller engines could benefit from the rod modification (better oil distribution).

I was also wandering if this is the bulletin that Jake refers to in the Bug Me video (referencing the removal of the head shim). What seems to be the general consensus on this shim? Remove it and lap it unless you need the clearance between the cylinder and the head?

Thanks,
Dave

[Oregon72]

What seems to be the general consensus on this shim? Remove it and lap it unless you need the clearance between the cylinder and the head?

Thanks,
Dave

Yes, you are correct. If your heads have been flycut, you may have no other choice but to use the head to cylinder metal shim or gasket - whatever the proper term is for it. The depth of the flycutting will determine that for you. If you have too deep of flycutting done and eliminate the shim, you will have a massive compression leak. You need the body of the head and the fins of the barrel not to be touching each other whatsoever (you can test this one the bench and by looking for the the gap when you lay the barrel on one of your heads - test all four of them) On my rebuild, I had no choice because the heads were flycut just a hair too deep - had to use the shim.

Good luck with the build - I had a lot of fun doing mine.

[Amskeptic]

I'm rebuilding my Type IV 1.7 liter and came across a technical bulletin for 2.0 liter engines.

The bulletin can be found at.... http://www.ratwell.com/mirror/sfraser/techbull.html

I was wandering if this can be used for 1.7/1.8 liter engines. The bulletin does state that it is for 2.0 (engine codes GD, GE, CV), but I thought that the smaller engines could benefit from the rod modification (better oil distribution).

I was also wandering if this is the bulletin that Jake refers to in the Bug Me video (referencing the removal of the head shim). What seems to be the general consensus on this shim? Remove it and lap it unless you need the clearance between the cylinder and the head?

Thanks,
Dave

The technical service bulletin that recommended deleting the sealing ring did not have to do with intrinsic weakness in the sealing ring . . . it had to do with instantaneous heat transfer to the cylinder walls. The 94mm pistons had a rash of seizures due to their greater expansion because of their greater mass. This would occur during transient overheats. The factory bulletin addressed this issue with a three-pronged attack.
1.) demand greater piston-to-cylinder clearance.
2.) cut notches in the rods to cool the pistons more readily
3.) delete the sealing ring to get the heavy load heat in the heads conducting down the cylinder barrels as quickly as possible to keep the barrels ahead of the piston expansion curve.

Notching the rods is a good idea for any of our Type 4 engines with known healthy cylinder walls and good piston rings.

Personally, I like the sealing rings well enough that if they help me get to the deck height I want, I'm using them. I also do that overnight simulation of heat-cycle 40 ft/lb head nut torque during an engine rebuild, then back down the torques in the morning to spec. Use the sequence in reverse.
Colin