302 popping and breaking up

[thejock60]

the motor still runs decent but makes all sorts of popping and almost backfiring kinds of noise when u rev it up (not while it's revving but when u take ur foot off the gas) the other thing is when the car is cool it doesn't do it, but when it reaches it normal running temp (about 180f) it starts doing it. I'm not sure if it's an electrical problem or a vaccum problem. I have underdrive pulleys and i know for a fact the system only charges 12.3 volts while at a idle and in 5th gear at 55mph the car only tach's 1500 rpm's. Any Idea's?

[PaulFiveOh]

I know it sounds silly but:

Check your header bolts, it sounds like the situation that happend to me when my left bank headers.........fell off.....lol yes fell completely off the head AS I was Driving!!! LOL, I knew it when it happend but a few days before that I was having those symptoms.

[thejock60]

I'll check them, I took it to an exhaust shop when it sounded as if i had an exhaust leak about 3 weeks ago and they said they didn't see anything but did tighten up the collector bolts.

thanks

[thejock60]

I went through and checked all the header bolts, intake bolts, and the carb nuts. the carb was a little loose and the rest were tight. The only thing i noticed was teh bracket the coil mounts to was loose. i tightened it up but i haven't had a chance to drive the car yet.

[Steves LX]

Is your backfire coming from the exhaust or the intake? Also what is your timing set at?

[plated]

sounds like a bad valve,bent or bad spring,were you beating on it when it happend?

[thejock60]

yea its gone through a few bottles. It started while at the track my fuel pump lost connection and shut the fuel off. The car also shut off when it happened, I was just hoping since it cut off in the middle of the pass and found where the ground had come loose on the pump and the car fired back up it didn't hurt anything. Hell if i'm going to have to replace valves I might aswell start building my other block and heads.


the backfire is coming from the exhaust. It's 12 degree's out total, for spray.

[thejock60]

I'll add a video of it shortly so u can hear what it's doing.

[thejock60]

http://videos.streetfire.net/video/caee048e-908a-44ba-ace6-999e012fe8d7.htm

engine cold ^^^


http://videos.streetfire.net/video/77081190-06f3-45ed-9129-999e01308136.htm
engine warm^^^

[Sparky]

It's a bad exhaust valve. Do a leakdown check to make sure.