Hopefully I will be able to help ya. I just put a pro billet msd distributor in my motor and had to play with the weights and everything to get my timing right.

Okay to set your timing first unplug the vacuum canister and plug the vacuum line. Then take the motor to 3000rpm and make sure you have around 34*.

Now this will be your total advance which = initial advance(turning the base) + your mechanical advance.

I said 34* because from everyone I talked to tell me 32-38* total advance so just get it in the middle and play with it from there. You want all of your advance to come in before 3000rpm so you may need to order a recurve kit. My original HEI was still advancing at 4200rpm!!

for example I have mine set up like so.

11* initial + 21* mechanical = 32* total.

It was cranking a little on the slow side when hot so i changed it to

9*initial + 25* mechanical = 34* total.

the engine is much more responsive since i changed it so i will keep playing with it hopefully for a better result. My engine is currently running smogger heads so yours is gonna be a litter different due to the more efficient combustion chamber of the vortec head.
dont forget to hook the vacuum line back up when your done! Hopefully this helped ya out!

 

I just rebuilt my sbc 350 which included a Comp XE 268 H Cam, Vortec Heads, Edelbrock Performer Intake and 1406 Carb, 10.5:1 HP Pistons, GM HEI Distributor from a stock 1972 engine.

The engine fired right up, and broke it in at 2000rpm. I went to put a timing light on it, it reads 38 Degrees with the vacuum line off the Distributor. I am wondering if that would be close to what it needs to be, I was guessing around 10-12 would be normal. The engine runs and idles fine, do I need to worry about the odd timing, or not since it seems to be running fine.

Is there anything that I may have done incorrectly during the setup of the dist when I converted from points to get this reading?

Any comments are helpful.
Thanks,

If it reads 38º at idle, either the damper mark and/or the timing tab could be incorrect, otherwise I'd expect it to be difficult to start warm w/that much advance, and it would be extremely over-advanced when the mechanical advance and vacuum advance was added in.

What I tell guys to do, is DETERMINE TDC, then MAKE A TIMING TAPE. The temporary timing tape is useful if you do not have a degreed damper or a dial back timing light.

If you're using a multiple discharge ignition amplifier, they can cause erratic readings from some timing lights.

The total w/o vacuum advance added in should be around 32º w/Vortec heads, all in by 2500 RPM. They do not need a lot of total timing. Run somewhere around 12º-16º BTDC initial, w/the vacuum can adding in another 10º-12º. Plumb the vacuum can to manifold vacuum.

To get all the mechanical advance in by about 2500 RPM will mean using lighter than stock springs from a kit. Keep your HEI weights and just swap out the springs.

Most HEI distributors seem to have about 16º-20º of mechanical advance built into them. Check yours to see just what it has- you may need to limit the total mechanical advance to prevent the total timing from being too high.

If the vacuum advance has too much advance built in, there are parts sold to limit the travel, or you can make something. If you might want to use an adjustable vacuum can to set where the advance begins.

A couple numbers for these parts:

VACUUM ADVANCE LIMITER PLATE- Crane #99619-1: 99619-1 INSTRUCTIONS.
ADJUSTABLE VACUUM ADVANCE CAN KIT- Crane #99600-1: 99600-1 INSTRUCTIONS.

 

read this.

http://www.corvette-restoration.com/resources/technical_papers/Timing101.pdf

 

I just rebuilt my sbc 350 which included a Comp XE 268 H Cam, Vortec Heads, Edelbrock Performer Intake and 1406 Carb, 10.5:1 HP Pistons, GM HEI Distributor from a stock 1972 engine.

The engine fired right up, and broke it in at 2000rpm. I went to put a timing light on it, it reads 38 Degrees with the vacuum line off the Distributor. I am wondering if that would be close to what it needs to be, I was guessing around 10-12 would be normal. The engine runs and idles fine, do I need to worry about the odd timing, or not since it seems to be running fine.

Is there anything that I may have done incorrectly during the setup of the dist when I converted from points to get this reading?

Any comments are helpful.
Thanks,

At what RPM?

What is your timing light?

Bogie

 

Check dist. weights and springs for smooth operation, Keep idle under 1000 rpm when checking the initial timing so centrifugal weights don't advance the timing. Could be simple fix if the weights are sticking.