340 exhaust manifold torque specs

-

jawbone

Cuda_queer
FABO Gold Member
Joined
Mar 17, 2017
Messages
645
Reaction score
301
Location
Richardson, TX
My FSM left this number out. 1970 340HP manifolds. Best I could come up with (see attached) but is for different something.

Screenshot_20220205-183340.png
 
Tight. I don't think I have ever used a torque wrench on those. Remember to use some sealer on the front and rear ones. They screw into a water jacket.
Thanks for heads up on sealer, have that covered. I can't get a torque wrench in there but I can make a reasonable guess if I can torque at least one.
 
Thanks for heads up on sealer, have that covered. I can't get a torque wrench in there but I can make a reasonable guess if I can torque at least one.
A 6" 3/8 drive ratchet shouldn't overtorque or a combination wrench. I always warm the engine up and snug them down as needed.
 
I think those are 5/16" bolts.
 
Last edited:
I think those are 3/8" bolts. They can take some torque.
They are 5/16 and for those reading this and are installing HP manifolds. There is a clearance issue, at least with "O" heads on drivers side, that does not allow manifold to sit flush with head so be careful. Had to make repairs to both center mounting tabs. Grind just forward of rear corner of head to correct. Sorry don't have any pics.
 
Last edited:
They are 5/16 and for those reading this and are installing HP manifolds. There is a clearance issue, at least with "O" heads on drivers side, that does not allow manifold to sit flush with head so be careful. Had to make repairs to both center mounting tabs. Grind rear corner of head to correct. Sorry don't have any pics.
I'll edit my post. It has been 15 years since I had those off.
 
You'll always go back and check them after a few heat cycles anyway.
 
I can't remember what I had for breakfast yesterday. Were all in the same boat at least I am.
5/16 studs on ends. I never did Toqure them. Just re-snugged um after a few heat cycles
And as far as not remembering goes. When your young you can say wow me and the guys went out last night. Can't remember part of what you were doing. Now that your older all ya gotta do is walk to another room of the house.......
 
Yup. I snug them, and especially with headers, retighten first few times engine is heated up. Gaskets compress, etc.
 
My Eddy hits the head on drivers side. I bought a head to manifold 1/4" spacer. Worked out great.
 
The key to this question is I have never used a torque wrench and once you have tightened the bolts down be sure to check and retighten them after the car has reached operating temp. They will indeed need to be snugged up a little more..
 
The key to this question is I have never used a torque wrench and once you have tightened the bolts down be sure to check and retighten them after the car has reached operating temp. They will indeed need to be snugged up a little more..
Thank you Gator.
 
-
Back
Top