asilomar244

I am in the process removing the intake and heads on my ’94 LT1 due to a blown headgasket. This is an LT1/T56 powertrain that was salvaged and has been used in an engine conversion. I was seeing high temp repeatedly and was not sure if it was a valid reading, or was due to the wiring from the GM sensor to the non-GM temp gauge. Anyways, the overheating happened repeatedly during troubleshooting of the cooling system. I have read multiple threads on this issue and reviewed my manuals and reverse cooling info. I should be able to figure that out. However, I ended up getting a lot of steam out the exhaust on cold start. As the motor heats up, the steam goes away and everything looks normal out the exhaust. So I figure this is a minimally blown head gasket.

I am going to take this opportunity to remove/rebuild the heads, inspect/replace the water pump, replace the opti, timing seal, front main seal, power steering pump, and some other misc components (sensors, connectors, etc.). Teardown of the intake in preparation for removing the heads showed signs of oil having penetrated the rear seal in the usual spot. The reason this is such a bummer is that I just repaired that leak for the 3rd time a month ago. I cleaned everything very well, used Permatex The Right Stuff (highly recommended from a Merc tech buddy of mine), used Fel-Pro intake gaskets, was not excessive with the sealant, laid a clean bead and was very careful torquing the intake down. I also checked the intake with a straight-edge and feeler gauge and found no warp to the intake. So the first thing I would like to know is, have any of you had to have the head/intake mating surfaces resurfaced so that the rear mating surface between the block and the intake seals correctly? Is there a different sealant you would recommend? Any advice on this would be great.

I will be checking in on this thread as I continue with the top end and front end rebuilds. I do have a couple questions on reassembling the valvetrain. The How to Rebuild LT1’s (Mavrigian) and Chilton manuals I have both spec a 22ft-lbs initial torque, then taking long and medium bolts and additional 80 degrees, and the short bolts 67 degrees. However, the Helm’s manual I have specs a three-pass torquing to 65ft-lbs. Which should I do?

The second valvetrain question I have is in regard to reassembling the rocker arms and pushrods and properly setting the valve lash. All three manuals say to tighten the rocker arm bolt until there is no free play in the pushrod and then tighten an additional full turn (the information on TDC and which valves can be adjusted when is also included and seems straighforward). Is there any more precise method for doing this or this the best way to set the valve lash? Does no free play mean no up and down movement or no rotation on the pushrod?

A few other questions I have:
-Should I plan on replacing the lifter and/or pushrods?
-Anyone know of a Bay Area CA shop that would rebuild the waterpump and power steering pump?
-Should I plan on replacing the tensioner?

I know this is a long post and I appreciate you taking the time to read it. I love my LT1 and want to set it up to run for many years to come. Any input you have would be great. Thanks.

sssalah

I don't recommend you do a full build up on the heads without at least re-ringing the short block. You would have to at least resurface the heads, check valve guide clearance and change the valve seals.
You can extend applying the sealant 1/2" over the intake gasket where the rectangular hole is. Apply an contiuous 1/4" bead and put the intake as straight as you can, this can be tricky with motor in the car.
The angle method is for torque to yield bolt (tty) which came on 96-97 models. You would need new ones as it's not recommended to reuse them once they are stretched. For 93-95 you can use the torque method.
The heads/intake surface needs to be resurfaced if the exessive material was removed from either the block deck or cylinder head deck. Either case would cause the heads to sit lower hence the intake to head bolts and intake ports wont line up correctly.
www.shobx.com has an accelent writeup on adjusting the lash check it out. I wouldn't go 1 full turn past 0 lash 1/4 makes me more comfortable. Zero lash is when the pushrod has some drag when rotating.
If the pushrods are straight and the ends look fine then there's no need to change them. As for the lifters I would change them if they're old 80-100K even if they're not damaged.

asilomar244

So far I am planning an OEM rebuild on the heads, and retaining the stock cam. Do you think this still will put too much pressure/strain on the stock rings?

sssalah

The problem is when the valves are laped and they seal very well compared with the piston ring sealing. If you don't lap the valves you should be fine.

#2

hey Stephan, it's Mike.

you should do a cam. turn it into even more of a beast.