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4.7L Stroker Jeep Comanche Exhaust questions

Posted: May 29th, 2014, 6:58 pm
by knever3
I have an '87 Comanche with a 4.7L stroker, (.060 over, '94 block, '96 ported head and a '99 port matched intake, Ford injectors, etc.)

The problem I am having is exhaust. I had a shop do a full exhaust on it and it sounds terrible! A resonance and droan all the time. I have the AFe stainless header installed but the outet is only 2-1/4" so the exhaust shop just used 2-1/4" pipe until it 90's around the oil pan and 2.5" from there on back. They just crushed the 2/5" pipe over the 2-1/4" with a standard exhaust clamp and it leaks still. They used that goop to try to seal the joints but it hasn't worked. There is also no flex joint installed and I am worried about that. He said it was rock solid and hung from the pipe. I wasn't too impressed with that either since the truck rocked on the lift overhead. They used a "like flowmaster" muffler.

So should I be conerned about cutting off the header outlet and having a stainless 2.5" put on?

I would like to go to mandrel bent tubing but no-one in my area does such a thing. When I go over a bridge I can hear the exhaust and it seems to be screaming out of the tailpipe so I think it's restricted.

What avenue should I take on the whole situation? I have an appointment on Monday to add a resonator, but I don't think that's the way to "fix" this the right way.

Can anyone recommend an exhaust shop in mid-Michigan that does mandrel bent exhaust? I wouldn't mind going stainless either, I don't ever want to have to replace a custom exhaust.

Re: 4.7L Stroker Jeep Comanche Exhaust questions

Posted: May 29th, 2014, 9:57 pm
by the grey ghost
Don't be afraid to cut the collector back a half inch and build your own transition , just make sure everything is test fit before final welding, mines cut to a 2 1/2 front pipe, mig welded stainless to a stainless flex pipe

Re: 4.7L Stroker Jeep Comanche Exhaust questions

Posted: May 30th, 2014, 4:10 pm
by knever3
the grey ghost wrote:Don't be afraid to cut the collector back a half inch and build your own transition , just make sure everything is test fit before final welding, mines cut to a 2 1/2 front pipe, mig welded stainless to a stainless flex pipe

Actually that's the last thing I want to do if I can help it. Will it really make that much of a difference all things being created equal? If I kept my current exhaust and just did that mod? I would love for a nice shop to make a full mandrel bent exhaust but I don't know of one anywhere.

Re: 4.7L Stroker Jeep Comanche Exhaust questions

Posted: May 31st, 2014, 9:40 am
by the grey ghost
I spent my money on a couple u bends from summit and welded it myself, welding stainless with a mug is tricky though but it looks nice, I think the pipe cost me around 60$, and I've got a little left over

Re: 4.7L Stroker Jeep Comanche Exhaust questions

Posted: May 31st, 2014, 1:57 pm
by wjtom
That is the reason i usually dont recommend flowmaster style mufflers especially the knockoffs.Try a magnaflow youll probably be alot happier.Took me 3 tries to get something that was quiet when cruising while still sounding good.Thats what i wound up using.Id definitely look for a different shop to do your exhaust work.