I have an 83 Camaro with the low output 305, and I recently took it out with a friend, and at one point the engine backfired, and ever since there has been a loud hissing sound, and the engine has stalls at idle. I can get it to run, and drive, but I have to keep on the throttle so the engine doesn't die out. From doing a little reading it seems that there might be a vacuum leak.

Upon a little inspection, the circled screw in the attached image was not present when I was attempting to find the problem. I think it might be another fuel line that was plugged up. If so, any suggestions with what to plug it up that won't fall out when a backfire occurs?

Any help is appreciated.

 

Welcome aboard thirdgen.org.

It's probably a vacuum line that's been plugged, but we'd need to see where it attaches to know for sure.

Does sound like you blew off a vacuum line somewhere. That would account for the noise and the idle problem.

 

Do you think it has something with the line that screw I circled is blocking? Because that wasn't there the last time I looked at the engine.

 

That grey connector off to the left of the picture mingled in the plug wires looks like the power lead for the electric choke, or at least thats the factory conector. Did you disconect that to take this photo or is it possible you missed that and the car doesn't want to idle any more cause the choke is stuck on from not being plugged in.

 

This particular picture was taken well before the engine started having this idle problem. It also doesn't have the factory carb, from what I understand. The guy I bought the car from removed as much as he possibly could to make the car as light as possible. No stereo/radio equipment, no heater, no a/c. Pretty much everything has been stripped, including the cat.

 

Well I don't have any personal experience with Holly carbs but I am used to seeing replacement power valves being sold in the parts catalogs describing them as better than the old design at not failing after a backfire. Somehow I think this may be a design weakness in Holley's.

 

Okay, so I found the screw that was inside that tube (somehow it managed to land in the engine bay and stay there...), replaced it, and now it's running properly.

 

Ah, you were saying the screw was there for the picture, but not there after the "incident". Misunderstood what you were saying.

Yes, that would produce a massive vacuum leak, which would make a lot of noise and would cause poor idling.

dirtywhiteZ28, look closer at the picture - there is a manual choke cable somehow attached to the electric choke thermostat.

Holleys come with power valve blow-out protection now. Wouldn't affect the idle circuit, anyway (those who say a blown PV makes their carb idle rich have a very badly adjusted carb).

Yim, the best way to describe what's been done to that car is something along the line of reprehensible. And that's just from your one picture.