torque specs for exhaust manifold?

I torqued my exhaust manifolds at 18 pounds, per the recommendation, and it was leaking pretty sporty around the gasket. Took it to my machine shop today to put on the sander and check to see if they were possibly warped but were not. He suggested I go back with some Ultra Copper this next time and recommended more torque [35 pounds]. It did need some resurfacing/sanding but not severely. Any wisdom out there ............ this was the first startup after rebuilding the engine and it has run about 15 minutes but smokes like a "chimley" around both exhaust manifold gaskets, especially on one side. This is a stock 1975 350 with quadrajet. Thanks .......

lane

 

Remove the gaskets. The factory didn't use them. I only used them if the head or manifold weren't in the best shape. I have never torqued an exhaust manifold, but it may require more torque when using a gasket. It's more important to tighten them evenly in several steps in the proper sequence than the actual torque.

 

What sequence do you use?

 

Thanks Larry ........... that was my reference too. I wondered what folks here on the forum thought about more torque and I take it you are saying 'go by this.'

 

I tighten them in a sequence like I do a cylinder head, a circular pattern from the center out.

 

Remember these are grade 5 3/8 x 16 bolts. They wont take much to break them off. Id not go more than 35lbs. I do mine at 20. For headers I use Remflex gaskets

 

I changed them all to grade 8 at the beginning as most of the originals were compromised ......... thanks everyone for the input ......... will look into Remflex [my overhaul kit was Victor Reinz]

 

I hope this isn't considered a hijack but, what would be the torque spec to an aluminum head with grade 5 bolts?

 

Larry, I am very much the same way ........ while not a mechanic I do often trust my feel given the variables of bolt size, application etc ........... btw - just ordered a set of Remflex gaskets and per the website I can see why Briz uses them as they seem vastly superior to what is usually available at the 'flaps' or other places .............

in response to Ray I wondered that too .... re: aluminum ........ mine are the old original steel

 

Most torque wrenches will not show 18 ft lbs. I use an in lb wrench: 18 ft lbs = 216 in lbs.

 

Bought a digital 1/4" drive Tq Wrench for just that reason. Valve covers and oil pan bolts. Found I wasnt getting near as tight as the book specs going by feel

 

I actually torqued my valve covers. Guess what? No more leak! 4 ft lbs is a lot tighter than you think. Somebody posted a thread on here several months back about 4 lb torque.

 

Honestly, it's the big torque that I worry about getting right ............ like 120 pounds and up ......... doing them by feel is out of my wheelhouse, maybe because that and much higher than that are for real men! and on an aside for Briz ........ the videos at Remflex said everything about why those gaskets are 'go to' products ............ thank you for the recommendation

 

That was me.

 

Use Remflex gaskets

 

Thanks Sean ............ they are supposed to be here tomorrow .......... my local hot rod buddies had not heard of them