Total Advance

[28buick]

I am trying to rework an electronic distributor in a chevy 350. The distributor is from a 1975. The motor is in a 72 Blazer with 3.07 gears and a slighty modified GM crate motor. What should I be setting the total mechanical advance to and the total advance with the vacum advance. The motor has never been over 3500 RPM and probably never will be. The truck is strickly a tow vehicle.

[JimKshortstep4x4]

We set our distributors up to get full advance in by 2500 rpm. The initial timing is set at 10-12 btdc and we curve the distributor to 24-26 degrees for a total of 34-36 degrees advance. Sometimes some fine tuning is needed but this generally works on a lot of engines. We have 72 4x4 which we use for towing which has this setup on a stock 350 engine and it performs very well at these settings. Good power and no pinging. We seldom exceed 3500
rpm on this vehicle.

Jim

[COBALT]

My 350 is a bit wierd. It has a 327 2bbl manifold on it, with single point ignition and externally resisted coil. When I tried to time it to 10-12 degrees from TDC on #1 it ran ok, but I had a bad stumble on acceleration even AFTER I rebuilt the carburetor. I ended up advancing it a few degrees more to get the stumble out. It's as about as far as I can get away with. Now it's at around 15 which is pretty damn high (I had to move the spark plug wires over one terminal on the distributor to get the clearance between the vaccum advance and the intake manifold upper passage!). That was the only way to get the stumble out. I've got great low-end power, but it's inneficient gas wise. I dirty my plugs up pretty badly. Also at idle it sounds like a drag engine.