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78 Darmah SD. Did the exhaust gaskets a while back. Just finished the card insulators. Followed instructions found here. All the stuff here says tighten them, but not too tight. How do I know tight enough?

I did the Yamabond, put back on the manifold, used the original nylon locking bolts to the point where about 1/2 to 1 mm of the bolt is peering out. Right side sounds great. Left (vertical) is backfiring big and bad. Wasn't there before! Blah!

How do I measure too tight?

Hey Peaky,
Do you mean that the backfiring wasn't there before the exhaust fix or the carb fix?
Are you sure that you are not leaking at the exhaust?.
As for the tightness of the manifold insulator gasket you should snug the nuts down until the manifold is mounted just so that you can no longer wiggle it then give the nuts about another 1/8 turn. What you don't want to do is crush the insulator. It is easy to crush it.
A previous owner has probably crushed the insulator to the point that it may have warped the manifold so that now that you have put on a new straight flat insulator a small amount of air may be getting through.
Instead of tightening it more to overcome this, take the manifold in question off and check to see if the mating surface is flat.
If not, get something very flat (piece of glass) and emory cloth and lap the surface until flat.
Yamabond remains fairly pliable so even if you used it and have an air leak some of the Yamabond (tiny bit) may have gotten sucked into the intake tract and left you still having the air leak.
Just some things to consider.
Hope this helps,
Dean

BD-

There was no backfiring either before or after the exhaust gasket change, and no backfiring after the new exhaust gasket and before the new insulators. Never thought about warpage in the intake manifold. Will check it out.

Thanks for the tip!

Sorted.

A little tighter on the insulators made it tight enough. Runs like its never ran before! I rattle windows and scare cats!

Next--new regulator/rectifier and a set of Autolite 425s.