Broken upper intakes.

[SappySE107]

I have seen 5 manifolds now with the same issue. The bolt holes are not going to take much abuse, especially on the corners. I have a manifold now with 3 cracked! 1 is in the middle, which is a first.

When shipping manifolds, please be sure the entire manifold is surrounded by something to cushion it from the box itself and any other parts in the box. When installing manifolds, make sure you torque the bolts to 18 lb ft and no more.

[rsisbetter]

my original 3400 upper was cracked exactly the same on all 4 corners, i wasnt sure how it happened, i torqued properly, sequence and 18ft/lbs. I thought it was an engine abuse/heat issue. heat mainly, everytime i would turn it off... PING...PING...PING gradually after shutdown. though never close to actually overheating.

[SappySE107]

Those are the iron exhaust manifolds making that noise. Im starting to think it may be the gasket/torque procedure. Perhaps slightly torque them all around like cylinder heads to make sure they are even all around instead of torquing a corner and working your way across. The plastic alignment pin on the gaskets could be warping the manifold on install.

[IsaacHayes]

I've had my 3100 small port upper off a million times, but it has 2x the bolts. Regardless I would snug them all up then go through and do the final torq down. I usually do like half, then go back and do the full torq. The 3500 upper is a little thicker too so it probably can stand more abuse. The large port 3100/3400 I can see as people cracking them if they don't do it right. Less metal there.

[pocket-rocket]

FYI Ben, I did NOT touch those manifolds Too bad I don't have/know how to TIG. I would hook you up.

[khellendrosxs]

I've had my 3100 small port upper off a million times, but it has 2x the bolts. Regardless I would snug them all up then go through and do the final torq down. I usually do like half, then go back and do the full torq. The 3500 upper is a little thicker too so it probably can stand more abuse. The large port 3100/3400 I can see as people cracking them if they don't do it right. Less metal there.

Same here, I never knew there was another way of doing it.