Timing is Driving me nuts!!!

-
jimbo

jimbo

Well-Known Member
Joined
Jan 2, 2008
Messages
345
Reaction score
13
Location
Seattle/Tacoma
I keep going back and fourth with the timing on my 340. Points dist, valve lift 480, 287 dur. If I set it to the card specs I have run-on when I shut the engine off. If I retard it, it won't readily start and I have no punch out of the hole. Will one of you pros walk me through it please?
 
Distributor timing has nothing to do with run on, remember the ignition is off. The cam you have should have the initial timing set between 15 degrees BTDC and 20 degrees BTDC. You need to find what the engine wants by advancing the timing in small increments while maintaining idle speed to get max manifold vacuum.

The run on is likely coming from the fact that you need to open the throttle blades quite a bit to get the engine to idle with timing at stock or less specs.

NOTE: you will likely need to restrict the total timing in the distributor if you find that the engine wants more than 15 degrees of initial. This is done by welding up the slots. Might be a good time to consider converting to electronic ignition with either a Mopar Performance or after market distributor that allows the distributor advance curve to be easily adjusted.
 
Run on comes from idle being set too high. Using a tach to set rpms ?
 
You are right on about getting rid of the points distributor. My compression ratio is unknown to me but I am sure it is a factor. .020 overbore Silvolights with valve reliefs, 360 j heads 1.60 2.02 valves, ported and polished, Torker 340 intake, Edelbrock 550. stock 273 exhaust. I am looking into the manifolds from a 360 Durango to open up the exhaust, and I have a Mighty Demon 750 to go on top. Break in is just about over, now we can get serious!
 
dgc333 said:
Distributor timing has nothing to do with run on, remember the ignition is off. The cam you have should have the initial timing set between 15 degrees BTDC and 20 degrees BTDC. You need to find what the engine wants by advancing the timing in small increments while maintaining idle speed to get max manifold vacuum.

The run on is likely coming from the fact that you need to open the throttle blades quite a bit to get the engine to idle with timing at stock or less specs.

NOTE: you will likely need to restrict the total timing in the distributor if you find that the engine wants more than 15 degrees of initial. This is done by welding up the slots. Might be a good time to consider converting to electronic ignition with either a Mopar Performance or after market distributor that allows the distributor advance curve to be easily adjusted.
Click to expand...

I let the idle go all the way and reset the timing at around 25 with vac. advance. Brought up the idle to 6 or 700 RPM. It layed rubber out the driveway. My neighbors are pissed, but I have no covanants. Screw 'em. Thanks!!!!:love7:
 
Jimbo: Just treat em like you want to be treated and you'll be ok. I think?

Us car guys don't need a bad name. Good luck on your car. Finally got my 440 cranked. Plug wires were in the wrong place from the shop. Sounds killer.
 
You're not hooking that vacuum advance to manifold vac are you? Try hooking it to ported if you haven't already. Far easier to get the idle to settle down.
 
You must log in or register to reply here.
-

Back
Top