Effects of significant exhaust leak...

[TJDIV]

I've had a pinhole size leak in the doughnut gasket just off the manifold/header, where the first break is.

Well. I drove it today for about an hour and a half, pretty regular driving, but the doughnut, what was left of it; gave up for good. The leak got very prominent, much louder and the engine seemed to not only get weaker acceleration (expected) but it also felt almost as if my timing changed on me just from the leak. My idling RPM's jumped 500 rpms over the course of 3 miles, but the temp stayed put at 190. The oil pressure is iffy, as the oil gauge I am using isn't what I would call perfect..(It's new, but gives innaccurate readings). I know the engine has oil pressure.

Anyway. How much effect can the development of a large exhaust leak have on an engine with a single barrel carb and stock set up? I know it's a lot, but looking for other opinions.

Let me know your thoughts. Thanks.

Tom IV

 

[Texican]

Anyway. How much effect can the development of a large exhaust leak have on an engine with a single barrel carb and stock set up? I know it's a lot, but looking for other opinions.

Let me know your thoughts. Thanks.

Tom IV

It should have little or no affect as to what you are describing, unless it is really heating things up under the hood (doubtful)
If you have a header and the leak is down at the collector, it is virtually impossible for it to have any effect
Now if you are breathing the fumes..........
If the leak is at the head, different deal, possible/probable intake leak also

 

[IDave]

I totally agree. That donut wouldn't do anything like that. Something else is up, Tommy. Like, a cracked manifold or some other intake leak.

 

[65swb45]

I totally agree. That donut wouldn't do anything like that. Something else is up, Tommy. Like, a cracked manifold or some other intake leak.

I concur.

 

[IDave]

Time for a vacuum gauge, Tommy!

 

[TJDIV]

sheeeeeeeeit. I don't need a vaccuum gauge!!!...ya'll should see how plain jane my set up is on the fuel/intake/exhaust end.

I replaced the doughnut/flange gasket and it fixed the "obvious" leak, and the prominent bounce with the "poppoppop" was gone.

But, I looked under the intake/carb mount and there are two empty bolt holes (think they hold a standard 9/16" bolt, it's a chevy 250)...so I plugged those up and elminated even MORE of the throttle/timing issue. I have one other vaccuum hose at the bottom of the carb that 'may' or may not be an advance option, but it's plugged.

As for now, I'm going to George's Muffler to run me a cleaner set up, I think my gasket issue is solved. But the riser gasket may need a replacement because of the lack of those two bolts keeping it tight. We'll see.

Thanks for the ideas. You guys were right, the intake holes were a big issue.