What to do?

mikelbeck said
Adam - "slap a new rear under it". You make it sound so easy! Got any spare 8-3/4s or 9" rears laying around? ;-)

7demon2 - I'm pretty sure the problem is with the intake gaskets, not the head gaskets. This happened once before, two years ago. Then I pulled the heads and the head gaskets looked ok. The intake gaskets looked bad, though. This year I pulled the intake off and the gaskets looked shot again.

longarm - that's exactly what I'm worried about, the rear blowing up and taking out the tranny.

68gts340 - If I put the intake on without using the cork ends it appears to fit fine. I found that if I used the cork I couldn't even get the bolts in properly. Without them (just using RTV on the ends) it's fine. I haven't checked with a feeler gauge, though, I'll give that a shot. Where would I check, just in the front & rear? Do I need to worry about the middle or not?

moper - Got any leads on a $4-500 bolt in 8-3/4?

I would check in as many places as i could, also take a machinest straight edge to the surfaces, the straight edge will show if anything is warped.
how does the port alignment look on the old gaskets ? you might be able to see any misalignment by carefully examining the old gaskets.. i have made templates for the heads and used them to check the port alignment on the intake also... using the bolt holes as the fixed point.( much the same as port matching ) these have to be pretty accurate so take your time ....for the shims i have cut sections out of the old gaskets ,( from the bolt hole area ) or even some washers will work, as long as they are the same thickness of the gasket, I used a light torque # around 20 lbs I think but cant remember for sure, use all the bolts, all with a shim. that way you can see how the manifold sits when in use, another tell tale is bolt thread marks on the upper half of the manifold mounting holes, it the bolt drags there it cant sit low enough. thread marks on the bottom of those holes and the manifold is to high .. or oblonged holes to get the bolts to start straight .. I actually had a very similar problem some years ago on a 340, drove me nuts....finally found a warped intake manifold... some one had opened up the holes to get the bolts to fit... I have been using silicone on the ends for years , great stuff.. .. go slow check every thing and good luck.....