Exhaust downpipe clamp torque

[DustyDave]

Does anyone know the proper torque spec or process for tightening the clamp connecting the exhaust manifold to the downpipe? I don't see any information on this in the shop manuals I have and I don't want to damage this connection.
Also curious on torque spec for the U-clamps to connect the rest of the exhaust plumbing... the downpipe to the center exhaust pipe and the center exhaust pipe to the rear muffler section? I assume too loose, risk of getting exhaust fumes in the passenger compartment, and too tight, risk of damaging pipes and not able to separate them later.
Thanks,
David

[OttawaTom]

Hi David,

I find this a useful reference when the manual doesn't have a torque spec:
http://www.wtools.com.tw/STANDARD-BOLT- ... RQUE.shtml

I'm guessing the bolt on the exhaust clamp is probably an 8.8 M8 bolt (so, 25 Nm, or 18 lb.ft). I found the clamp bottoms out before I hit any high amount of torque.

-Tom

[18Fiatsandcounting]

Thanks, Tom, that's a useful chart. As for David's original question about the torque spec for the exhaust pipe clamps, I've never seen one. A lot of muffler shops that I've observed over the years often just tighten it up with an impact wrench, and while they may have their impact gun turned down to tighten to only a certain point, I'm guessing they just tighten really tight. And they just put on new muffler clamps with each job, so they're not worried about damaging the threads.

But, based on my own tightening and loosening of exhaust clamps over the years, I'm guessing in the neighborhood of 30 ft lbs. You would have to get a lot tighter than that to deform the pipes enough to make them hard to remove later.

-Bryan

[RRoller123]

I was gunna say around 30 too, maybe a little more, and I put Ni anti-seize on exhaust nuts and bolts.

[DustyDave]

Thanks to all! I hope to put the exhaust system back together this weekend. I’ll play around with the torque values given on some scrap pieces and see what seems best. Thanks again, appreciated!
David

[DustyDave]

I tested on a few scrap pieces. 20 ft lbs was enough to deform the pipes so they could not be separated. 14 ft lbs seemed tight enough for a good seal but not deform the pipes, so that is what I used. Thanks to all for the discussion and feedback! My engine is not yet running to test it out, but I’ll update if anything needs to be changed when I get that far.