I have a 67 El Camino with a stock 350 other than headers, a holley intake, and a Carter AFB Comp Series 4 barrel carb. This was on her when she was adopted and I am having trouble getting the feul/air ratio right. When I run 93 octane she almost runs right, but not quite, and if I run 87 she gets completely pissed and pings bad on acceleration, and then diesels when shut off for a good 10-20 seconds. The timing is set as far down as possible in order to try to reduce the pinging, but it still does it. I was under the impression that its the carb, seeing as i checked all vacuum lines and have no leaks. Any help is very appreciated.

Well i feel that if it "almost" runs right with 93 octane it's in your timing. A lower octane which causes pre ignition will also put a glow inside your heads and will diesel. Also to high of an idle speed setting when things warm up will cause a diesel. You state your "timing" is backed off as far as possible ? What is your timing set at ?? Have you checked timing @ 3000-3500 rpm to find out what your total is. You can have 8º initial and 35º @ 3000 rpm and it's good to go BUT most just crank +12-16º initial to get around 34º at 3000 rpm. "bad move"

Jim

Tucker, do you know your compression ratio? Do you know your cam specs? These are important.

You also need to know your timing. Initial + mechanical = total. You should have the vacuum advance disconnected when you check these.

Another thing is that you could have too much vacuum advance. Have you tried driving with the vacuum advance disconnected? If not, give it a try. Be sure and plug the vacuum port on the carb when you do this.

If it's a stock GM HEI ignition, it likely has lots of vacuum advance in it.

If you think it's the carburetor, get a strip kit and follow the tuning instructions. But don't go to the carb until you know what's happening with your timing.

------------------
My Web Site (http://www.landry-family.com) (updated 01-04-03)

"Long Live Freedom!"

Chad Landry
TC Member #643
ACES Member #4556
'68 El Camino