Ram horn manifold

[Breadstick]

If anyone was wondering what size bolts to get for the OEM 350 exhaust manifold, the thread size is 3/16 24 and the middle size is 2 3/4. I found this through trial and error and I only found ONE bolt this size between Lowes, O'reilly, Napa, and Advance auto parts. I have lots of 3", so I'm going to have to cut them down. Apparently no one wants to run the original manifold anymore.

[MJN]

which bolts- manifold to cylinder head? They should be 3/8-16 thread size. I've never seen a fine thread manifold bolt and 3/16" diameter is much too small.
I've ordered manifold bolt kits from Corvette Central. https://www.corvettecentral.com/c3-6...f%3fcount%3d18

[LNP]

I run the original ram horn manifolds on my LT1 350 and use the stock bolts which are 3/8" x 16 national coarse thread. In all my 30yrs in garage work I've never seen a bolt smaller than 3/8" on a small block Chevy. If someone broke the original bolts off maybe they drilled and tapped them a smaller size. I would be worried about a 3/16" bolt not being able to hold the exhaust manifold in place for very long.

[Grumpy old man]

Don't forget to use anti-seize when installing the bolts , Someday you'll need those bolts to come out .

[Breadstick]

Sorry everyone, I meant the correct length is what I'm having trouble getting. My 72 had headers and a terrible, too short exhaust when I got it. Going back to stock-type, so I didn't have the original manifold bolts to bolt to the engine, just the short ones for the headers.

[LNP]

Originally Posted by Breadstick

Sorry everyone, I meant the correct length is what I'm having trouble getting. My 72 had headers and a terrible, too short exhaust when I got it. Going back to stock-type, so I didn't have the original manifold bolts to bolt to the engine, just the short ones for the headers.

Ok cool. Do you still need to know the correct lengths? I could always pull a few of mine out and measure them.

[Breadstick]

Originally Posted by LNP

Ok cool. Do you still need to know the correct lengths? I could always pull a few of mine out and measure them.

No thank you. I know the correct lengths, I just can't find them. I can get 2 1/2" and 3" length everywhere but I can't find 2 3/4" anywhere in grade 5 or 8. I have some 3" grade 8 in the right pitch so I'm going to try to grind the last 1/4" off and see how that goes.

[72c20customcamper]

Originally Posted by Breadstick

No thank you. I know the correct lengths, I just can't find them. I can get 2 1/2" and 3" length everywhere but I can't find 2 3/4" anywhere in grade 5 or 8. I have some 3" grade 8 in the right pitch so I'm going to try to grind the last 1/4" off and see how that goes.

I would cut rather than grind off a 1/4 inch I got one of these a few months ago it works great for chamfering bolts tubing and rods

[firedemon]

try ARP they usually have everything probably not cheap though

[Accelo]

Fastenal has them.

[Grumpy old man]

Bolt depot .

https://www.boltdepot.com/Hex_bolts_...ow_3_8-16.aspx

[Richard]

McMaster Carr is another source.

[72c20customcamper]

Fastenal

https://www.fastenal.com/product/fas...egation=Length

[LNP]

Originally Posted by Breadstick

No thank you. I know the correct lengths, I just can't find them. I can get 2 1/2" and 3" length everywhere but I can't find 2 3/4" anywhere in grade 5 or 8. I have some 3" grade 8 in the right pitch so I'm going to try to grind the last 1/4" off and see how that goes.

https://www.mcmaster.com/hex-bolts/m.../length~2-3-4/

[fatbass]

I've cut bolts off before and found that if you run a thread die down the bolt, make the cut, then unscrew the die, the burr come off and the bolt will thread into the head easier.