Exhaust Mainfold Torque Spec

[Thomv]

I believe the torque spec for my 454 big block should be 25 foot pounds for the exhaust manifold bolts. I just need someone to confirm that number. I also need to know what size allen wrench do I need to purchase for the manifold threaded brass plugs. I was at Sears today buying a 17 mm allen wrench but when I got it home it was a tad too big to fit into the plug. Not even sure if it actually is a metric size. Looks like there other size was too small.
Thanks

 

[90stingray]

Re: Exhaust Mainfold Torque Spec

A lot of times on the large allen plugs.. I can usually take a bolt and find a bolt head that fits into the hole. If not a few passes on the grinder and I will make one fit. It should be a sae size. Then just weld a nut on, or tighten two nuts together on the threaded shank and you have a new plug install tool! You can install them with a socket and ratchet. As far as the torque, sounds pretty close... I am thinking it was 30 ft lbs for some reason. I will try to dig up a spec...

 

[MarkSee]

Re: Exhaust Mainfold Torque Spec

According to service manual 23 which shows being for a 454 CID (7.4L) / 502 CID (8.2L), Page 3A-3:
Exhaust Manifold 25
Exhaust Manifold Elbow 25

Mark

 

[Thomv]

Re: Exhaust Mainfold Torque Spec

Thanks for all of your help. I will go with the 25 foot pounds. I did use a bolt head and it turns out to be a 9/16 bolt head. I will use a bolt and two nuts to make up my allen wrench to remove the threaded plugs. I do have two more questions. One, do I need to use any type of exhaust gasket sealant between the gaskets and mating exhaust parts and second, do I use a pipe sealant or on the treaded exhaust plugs?
Thanks

 

[90stingray]

Re: Exhaust Mainfold Torque Spec

You can use some pipe dope to help lube the threads to help them go in. Just remember, you are most likely not going to be able to get them all flush into the manifold. It sure looks better when they are but I wouldn't want to split my manifold trying to bury in a plug. Just good and snug. Just a heads up for ya...