[artis67]

Hello all,

I have a 69 Camaro 396 4sp that has been giving me problems since getting stuck in traffic earlier this summer. It all started out after getting stuck in traffic for about 2 hours idling. It wouldn't accelerate properly and I really noticed on the highway it would lurch. I figured I had a bad plug or wire, but after replacing the plugs, wires, cap, and rotor, I decided it must be fuel-related.

I re-built the carb (Holley 750 4013 mech sec) and replaced the fuel pump and filter. I did find a chunk of rubber or something in the secondary spray nozzle. I also found the 3/8" fiber-tar base gasket was likely leaking. I was so excited, because this must have been it. It did run a little better, but still is not where it was. My fuel pressure bleeds off pretty quickly after shutting down (couple minutes to 0). Now it also idles pretty rough.

I then suspected vacuum and heard a hissing sound after I shut it down and found the brake booster check valve grommet was leaking. Replaced that and it must run better right? Maybe a little, but still not where it needs to be. I hooked up a vacuum gauge to the manifold and get 10-15 erratic Hg. When I rev it up to ~2k it steadies out at 15.

I guess my questions are:
Is this erratic vacuum normal for a lopey cam? Does erratic vacuum suggest a worn valve or seat. If so, can I check without pulling engine apart?
Would the fuel pressure bleed-off affect acceleration and idle?
Is there anything I missed in the trouble-shooting process?
Is there any information I left out that would help some of you fine gents help me out.

Thanks in advance.
Josh

[batboy]

A lopey cam might cause low or erratic vacuum readings, although I'd check all vacuum hoses and fittings first. If it was running ok before the stuck in traffic point, it's probably not the cam causing the main problem. If you have a worn or burnt valve/seat a compression check will locate that problem. Perhaps the motor overheated during that 2 hours of idling?

[artis67]

Thanks for the reply. It never got over 180°. I inspected all the vacuum lines and they seem to be ok. You think the vacuum I have is in the ballpark? Is there a good way to check the manifold gasket other than carb cleaner? I would like to rig up a low pressure air regulator and measure decay, but don't see anything readily available. Does anyone have any experience with this?

I will check the compression and post my findings. Any thoughts on the fuel pressure? I have a new fuel log coming.