Recently bought a 69 Camaro pretty much 'turn key' condition. It is a 350..Edlebrock intake...and carb. Hei ignition and a small cam. I have no idea what size cam...what style lifters...piston type or much of anything else. How am I supposed to time this thing? I seem to have a little hesitation on hard acceleration and sometimes it will diesel on shutdown. Any starting place?

Thanks for your help guys and gals

Gary

hesitation might be from many other things...

set it at 7 deg at idle it will start and run descent...its a start smile.gif

when you turn the key off it cuts power to the ignition which turns off the spark...so ...dieseling has nothing to do with timing ;)

turn it off in gear or let the clutch out a tad to slow the motor down when turning it off... ;)

im not sure how to help dieseling...better gas maybe...maybe somebody will chime in and teach us smile.gif

im pretty sure a car will diesel if it has to much timing.

Run-on (dieseling) is caused by a couple things. One is excessive carbon buildup in the cyl head and hot spots in the carbon act as the spark after the ignition is off. Usually only high mileage engines that have been neglected have this problem.

Typically the idle adjust is turned up too high. Turning up the idle opens the primary throttle blades and if they are open too far when the engine is shut down it will run on.

To fix this check your initial timing, if it's not advanced enough you will have to turn up the idle screw to get the engine to idle. Typically factory idle (initial) timing with the vacuum advance disconnected and the source plugged is 4 degs btdc. Your engine will like as much as 12 degs or more btdc but be careful and adjust it in 2 deg increments and test for WOT pinging. As you increase the timing the idle will go up and you can back off on the idle adjustment screw closing the throttle blades some. You should be able to find a combination of timing and idle adjustment where the engine doesn't ping when driving and it shuts off and doesn't run on...

Another adjustment that could cause you to have the idle adjusted open too much to keep the engine idling is the idle mixture screws. If you have them too lean (usually turned in too much) you will have to open the idle screw to compensate. Put a vacuum gauge on a manifold vacuum source and adjust the idle mixture screws for the most vaccum on the gauge. The idle should also raise as you richen the idle mixture letting you lower the idle with the idle adjustment screw closing the throttle blades some.

This is very common and very easy to fix.

Dennis, thanks for the additonal info on run-on.. I dialed my timing back to 4*btdc and dropped the idle down. Looks like I finaly kicked the run-on.

Brandon J.

To fix this check your initial timing, if it's not advanced enough you will have to turn up the idle screw to get the engine to idle Dennis, I hadn't thought of it that way before, but I'll bet you're right. One of the many ways that timing and carb work together. graemlins/thumbsup.gif