72 gmc timing

[davidbakker]

I have a 1972 gmc 1/2 pickup with a 350. I have changed the distributor to an hei with a 65,000 volt coil. The carb is an edelbrock 750 jetted down to a 650. It has an rv cam and I don't know the specs. What should I set the timing at?

[piecesparts]

The timing for a GM 350 is usually around 6 BTDC. I wouold start at 12 and work on advancing the timing to get more performance, without detonation. The 750 carb jetted dwon to 650 is only leaning out the fuel/air mixture. That will still flow more cfm of air than a 650 CFM carb. You may have some stumbling issues with that setup on the carb.

[swamp rat]

Anywhere from 12 to 8 is probably where you will end up, just make sure it dosn't detonate when your accelerating, or want to diesel when you shut it off. i ended up around 10, i have a mild cam and about 9-9.5:1 compression.

If it does stumble make sure you have the accelerator pump rod in the closest hole to the pivot point. this gives a quicker dose of gas to the circut.

[GASoline71]

To add... also open up your spark plug gap to .045 when stepping up to an HEI.

Gary