Timing 12 initial 22 total?

[DuallyFlatbed]

Hey guys, my first post!

I picked up a 70 c-30 about a month ago and have been trying to get her running right since.( it broke down halfway home, flooded out)

Its a 283 out of a 65 c-10, with a 68 buick lesabre quadrajet on top. Atleast thats what my research shows. Im assuming motor is fairly stock built.

I rebuilt the carb and now shes running ok, but i figured i'd give her a tuneup before i go break down again. I'm trying to set the timing but thats where im running into problems.

I set her to 12* intial, dizzy vac unplugged.

I reved it where the timing stopped advancing and got 22*. (no tach to go by)

Shouldnt it be around 34-36? With the dizzy vac hooked back up i got around 41* before it stopped advanceing.

Its a points ignition, and i just figured out how to use a timing light 2 days ago. Any help would be appreciated guys.

[Kerry P]

You're right total mechanical advance should typically be 34 to 40 degrees. Compression and cylinder head chamber design being big variables in total timing. Camshaft duration has a big effect on the curve and initial timing.

Old iron factory heads often use about 4 more degrees of total timing than modern heads. I found Vortecs to be very sensitive to total too much timing. Sort of a by product of their efficient chambers.

Don't try to use the vacuum advance as a band aid. It will look right using a timing light but under load you won't be making the vacuum you do while you're reving and setting the timing.

Kerry P

[DuallyFlatbed]

Thanks for the tips

When i first checked the timing it was advance around 20 or so, it was up there. I googled some more and im thinking its spring loaded arms on top under the cap.

I guess thats why they had it timed so high, to compensate for the bad dizzy.

[LEEVON]

replace the bushings and springs, that usually helps and you can also get adjustable vacuum advance canisters for a few bucks.

[Kerry P]

Mechanical advances get dirty, get rusty and/or wear and then stick or become erratic.

It's a good idea to take a look under the cap. Sometime cleaning and lubricating fix the issue.

Kerry P

[DuallyFlatbed]

The arms looked pretty corroded. This distributor is gonna need some work put into it and i dont really spend any money on the points system thats on it now.

I've got another SB chevy thats got a HEI on it, im gonna just throw it on the truck for now to get it running and worry about a dizzy for the other chevy later.

Thanks for the replys guys, i appreciate the help.

[Kerry P]

Originally Posted by DuallyFlatbed

The arms looked pretty corroded. This distributor is gonna need some work put into it and i dont really spend any money on the points system thats on it now.

I've got another SB chevy thats got a HEI on it, im gonna just throw it on the truck for now to get it running and worry about a dizzy for the other chevy later.

Thanks for the replys guys, i appreciate the help.

Just something to watch for: Typically an HEI works with full voltage and the coil on a pre=HEI vehicle is fed with reduced voltage via a "resistance wire".


Kerry P