'77 Dual Exhaust Conversion

JAD77

New member
Joined
Jun 16, 2010
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4
I am finally putting my 77 back together and have purchased a dual exhaust system from Corvette Central. The system came with no instructions so it's hard to tell what pipe goes where. Since the original system had a "Y" pipe, I'm not sure where the dual hangers go on the frame. Also, I am installing the system with the body off the frame so it's a little difficult to tell if the mufflers are in the correct location. Someone from another forum was nice enough to upload a couple of pictures but it was still difficult to see the layout. For some reason, when i put the hangers where his photo indicated, the middle interim pipe seemed to be too short by a couple of inches. The system was listed as a '74 exhaust system for manual tranny with 2 1/2" pipes, but a newer catalog lists the same product number for a '77 so I am guessing that there is no difference. Any help, photos or diagrams would be very much appreciated. I expected that this would be a slam-dunk, especially with the body off but who'd a thunk? Thx, J :hissyfit:
 
Without the body in place it's going to be difficult to "guess" the best location for the mufflers (and the tailpipes for that matter)... just install it loosely for now until you get the body on the frame, then align all the pieces and once verified none of the pipes is hitting the floorboard tighten the clamps or weld.... make sure the pipes are not hitting the frame at the holes in the crossmember, that's a tight spot and it might rattle when you're driving.
 
Jadd77:

Are you using an earlier 2 hole hanger unit at the crossmember? My stock '76 only had one hole because of the Y pipe use.

I purchased a 2 hole unit from Chevrolet. From a '74 'vette, I believe. The last year for factory true duals before the Cat.
 
Only 1 hole? I have never seen a 1 hole crossmember, as far as I know all cars up to 77 had 2 holes and the 78+ ones had the hump style which can be swapped for the earlier one but it's not 100% bolt on. The bolts that go up in the frame are but the through bolt location is a little different (why they ever changed that is a mystery to me)
 
Thanks guys. I got a twin pipe hanger for the tranny mount and is looks like the pipes will sit properly through the frame holes. Looks like the rear hanger locations at the mufflers is the problem. I will leave thos hangers loose until the body gets put back. I'll try to upload some pictures. Do I just load them onto my computer then attach them through the Image Hosting drop-down? j.
 
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