Hey ugys I jsut bought a car ( 89 formula 350 ) the original owner took the muffler off because the inlet pipe busted at the fitting, so he jsut took from the muffler back off. Anyways, is there a big chance that I will burn a valve if I keep running it this way" it still has a cat and all I dont dont rev the engine at all, so there inst a big chance of a back fire. just kinda curious. PS it sounds cool and its not overyloud I guess thats because of the cat and the stock manifolds.

 

I drove my car around with no muffler for a long time. I dont have burnt valves. It does sound great. You are correct, it is not excessivly loud because of the cats and stock exhaust manifolds.

I do have valve stem leaks, but most SBC's do. I don't attribute it to the no muffler, but rather, to 100,000 miles.

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1989 Chevrolet Camaro IROC-Z
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hahaa, cool, Im just worried about it eeveryone is telling me youll burn your valves, the way I figure it is if I dont rev it all to hell and let it back fire then I dont have to worry about it. although I do want a loud *** muffler that still sounds good.

 

The "open exhaust = burnt valves" scenario assumes cold air backflows to the valves that are held off their seats when the engine stops, and warp due to non-uniform cooling. For that to happen, you'd have to have pipes about a foot long off of each cylinder. It certainly isn't an issue when the cool air has to travel several feet from the former muffler inlet, through a cat, and then the y-pipe and manifold.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

good. I didnt think there was muchg of a chance of me burning valves, but I wanted to be on the safe side.