[70bird]

Last Friday night a group of us were cruising our muscle cars around town.

Towards the end of our cruising a buddy in his 68 Camaro (383ci) jumped on it and took off a bit. It sounded and looked great. I wanted to return the favor so when I was next to him (we were doing about 40mph) I dropped it into second gave it a little gas, let out the clutch and punched it to play a little 502.

Man was it a show. There were fireballs going everywhere. A buddy behind me thought I had installed flame throwers. I saw a couple flashes thru the cowl hood also.

To say the least, that wasn't my intent. My car typically runs very well.

The engine didn't rev at all. Now, if I give it a little more pedal while under load, the fireballs return. I have to give it a lot of gas and keep the rpm's above 1500 or idleing. To say the least, the 5 mile trip home was fast.

Now, when not in gear, if I give it just a bit more throttle than idle it just goes silent and dies. If I give it about 3/8s throttle, off idle, the engine sputters but jumps to about 1500 rpm and after about a second jumps to about 3K (with no extra pedal). Also, it is idling at about 400 instead of the normal 600-650 when warm.

I was thinking spark scatter so I replaced the 10 year old (20K mile) cap and rotor which were a little dirty inside and had some buildup on the contacts. I also replaced the plugs b/c I had been wanting to check them out anyway.

This didn't help the issue at all. I'm going to rebuild the 750 Holley HP DP tomorrow and pull the distributor to check the gear. I just added the HP main body last summer and installed an MSD ignition module at the same time.

I was planning on going to the track this Friday night, running slicks for the fist time, since it's the last test and tune of the season. Maybe it's a sign.

Any other ideas? I'm also considering the magnetic pickup or a more involved repair such as the timing chain jumping a tooth.

Also, the engine is not happy at any constant rpm. The rpms have to be increasing or it will die (other than at the 400 rpm idle which sounds like it wants to die).

Sorry for the long read.

 

[DoubleVision]

Do a spark test with the car at idle. If the spark is yellow it`s weak. Also make sure it`s firing regular intervals and not every other. A friend of mine`s truck did this and the problem was the ignition was only getting 8 volts instead of 12, while I don`t think that`s the issue you have it does sound ignition related.

 

[backardracer]

maybe the timeing chain took a jump

 

[T-bucket23]

You need to test and not guess. I would first check fuel pressure to see if it is within spec for the system you are running.
Next I would pull plug wires one at a time while idling to see which ones make a difference in how it runs and which ones don't. Once you have this info, then you can start to trouble shoot.
There are many things that could be wrong, from a bad wire to a sucked in gasket.
A vacuum test may also shed some light.

 

[70bird]

Well, cleaned out the carb, checked the power valve, replaced most of the gaskets and what do you know, she runs great again.

I would have almost bet money that it was an ignition issue.

I didn't think it was a plug wire b/c it wasn't missing at all. Before I pulled the carb I bumped up the timing to see what affect that would have. I could tell it was advanced but it still wasn't behaving normally.

The vacuum gauge was reading fairly normal aside from the having to play with the pedal to keep her running on the street.

The fuel pressure gauge read constant during the whole ordeal.

Thanks for the ideas and suggestions.