What length bolts? Exhaust Pipe Flange (440 cui) H

[slsc98]

Hello!

Can anyone tell me what bolts I need to reconnect the driver's side exhaust pipe flange on a 1970 'GTX' 440 engine?

(The 440 now sits in my '73 Challenger.)

I am pretty sure I need two (2) fully threaded 7/16"-20 bolts + nuts but, I am unsure as to what length they should be. (The Service Manual tightening reference indicates only a 7/16-20 nut.)

I appreciate any assist -- I am picking the replacement gaskets up tomorrow!

 

[slsc98]

Follow-up-date: I got several excellent assits/responses from the brother-sister boards at both Moparts.com and Cuda-Challenger.com :

Mopar Big block engine exhaust pipe to exhaust manifold?

Bolts are 7/16-14 1.75", 1.25 of which are threaded (i.e. not full thread) the head is .28" high and the head is 5/8 Trim. Grade 5 phosphate finish. Part# 6029004

The nuts are 7/16-14 marsden nuts, phosphate finish as well. Part# 9429434

Quick search found these:

http://www.billrolikenterprises.com/proddetail.asp?prod=6029004-P

Not sure but I'm thinking 1.5-1.75.... And I prefer to use what is called "Stover" nuts, They are a type of self locking nut that uses a slightly distorted thread to create the self locking effect.. Any nylon lock insert will melt... These are called Stover nuts because they were designed for use on the fire box of old stoves.

They don't need to be full thread, manifold 1/2" + gasket + flange, can use 1/2-5/8 shoulder.