I had my entire engine blow this past month and replaced it with a new 350. The original 305 that blew was stock with just a cutout before the Cat.

Now that I have the car back with a 350 in it... I am hesitant to take the cover plate off the cutout.

My mechanic said the cutout could have caused my engine to go. Is this true? It doenst sound like a simple free flowing exhaust would creat such problems.

Bottom line, is it bad to run it without the cover plate on the cutout? Noise and emmisions is not a problem, the only thing i am worried about is if the engine will be damaged from the cutout being open. Thanks guys... hope to hear from you soon.

 

That's a negative ghost rider, the cutout is fine.

IMO, the whole deal about short exhaust making it possible to burn a valve or suck a valve is a load of I have heard people say that if you run your car uncapped or with too short of exhaust, your engine will suck cold air back through the exhaust causing you to "suck" or "burn" a valve. I am sure this is what your mechanic meant, and I think it is a fallacy. Maybe, though, your exhaust flowing more freely caused a lean condition that lead to demise of your engine.......Probably not tho. Go ahead and use the cutout, but make sure when you uncap it you tune accordingly.

 

well it has a gutted cat on there now with a flowmaster muffler, and its tuned to that... so does it need to be retuned for the cutout?

 

how often do you run the cut out? I rarely run mine, runs great

 

it would be open all the time

 

Well I have never run a cutout, but the theory involved is all the same. If you make the exhaust flow more freely, you will be letting air out easier, and you would then be letting more air in. If you are not making the exhaust flow more freely, (due to an already free flowing exhaust) it wouldn't be necessary to re tune. It also wouldn't be necessary to open the cutout. Unless of course you just like it to be loud. LOL

 

Almost forgot to say.....
There is a chance that the extra flow provided will affect the mixture so little that it wouldn't even matter......I was just trying to assess the possibilities your mechanic had in his head about how the cutout blew up your engine.

 

so ill be fine with running an open cutout all the time then?

 

yes

 

Cutouts will not cause problems for your engine. If they did, no one would buy them.

 

completely agreed. I've had my cutout for over 2 years now...no problems at all

 

one more thing... i was talking to my friend who is also a mechanic... he said cutouts arent entirely bad, but they could cause damage to the cam. I dont remember how he correlated this... but has anyone heard of this? I will talk to him again tonite and get his actual explanation and let u guys know what he meant...

 

This mechanic buddy... where is he located so I can be sure to never go to him!!! WTF are people thinking?!?!

A cutout will not hurt an engine, and for damn sure won't hurt the cam. Throw out the BS Flag in his face on that one...

 

On TBI cars, the reduction in backpressure can cause problems with the positive pressure type EGR valve. It can also mess with the SD system's brains and cause excessively lean mixtures.

With proper PROM tuning, there are no problems with running open exhaust vs. closed. However, if you switch between the two and don't tell a SD system which you're running, you can cause problems.

But not with the cam...

 

So im getting the impression its fine to run with it open.. one more quick question...

when im driving... when i let off the gas, it makes a weird like riumbleing noise from the exhaust other then the normal rumble... it sounds kinda outta place... could this be that reversion of air coming back in or is it a common sound with cutouts?

 

There is no way that engine damage will be caused by the cutout, excepting as has already been stated that you might go lean. THAT might cause a problem. The Cam? No way. Hes' smokin' rope.

Troy
So Cal

 

Definately sounds like you need a new hired wrench. Or learn to work on the car yourself. (the second option is alot more fun)