Setting up my timing curve here, old style GM non-cc distributor, crane adjustable vacuum advance kit, with limiter tab, and aftermarket springs.

my cam is 227/234, and has 1.6 rockers on it.

I've had to drill holes in my throttle plates to keep the sucker running. I've also drilled out my idle mixture screws (non-cc qjet). Still don't have any adjustment with those...

I'm pulling ~10" vacuum at 800RPM idle.
anyway, so far for timing, i've got 24* initial, vacuum on ported, and a light and medium spring. Manifold vacuum made it hunt for at idle, then stall out...
I know I need to shorten my mechanical advance, so tonight I tore down my distributor, and welded one of my mechanical advance slots, to about 75% as long as it was before.... Now after putting it together, it seems like the weights hold the pins in the center of their travel, and only half of what I thought was it's travel, is actually it's travel. So now I have what i'm guessing is about 5* of mechanical advance travel, not even enough to stretch out the springs.. know what i'm saying?
Did I goof up? Can I grind my weights to work? or....?

I'm hoping to set up my timing curve right, meanwhile put on my exhaust, then do carb tuning.
any thoughts on timing or carb setup would be appreciated. Thanks.

 

The weights and center cam determine how much mechanical advance the distributor gets. The springs control the rpm that it advances.

You want to set it up so that it goes to full advance at around 3000 rpm.

Initial timing plus mechanical equals total. Depending on what the engines likes, total can be between 32 and 40 degrees. Forget about the vacuum when setting up a distributor. That's just for part throttle loads.

 

ok yea, I got that. I'm trying to limit my mechanical advance, so I can run more initial and not go too high.



I think I goofed, I re-assembled it a few times, and it seems to turn against the springs, and snap back nicely.

ok, think I got it figured here...

 

Hey, my engine doesnt really start good untill about 23 degrees, which i figured with the cashaft i installed. it wont hardly idle @ 23 degees, i have it set at 28 degrees now at idle. Still windmills @ 23 degrees, but not as bad. im thinking on going higher. I dunno
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mine pulls 10" of vacuum at 800 rpms to mines a crane cam, solid lifter

 

Did ya weld up the wrong end of the slot? you want to weld up the end that the pin hits at high rpm ( when the weights are pulled open. Not the end of the slot that the pin rests on at idle. you may need to drill out the idle fuel restriction. This requires a special long shank mini drill bit.
be carefull .002" makes a big difference.
Consult the Qjet book by Doug Roe to see how to richen up the idle fuel restriction.
You can tell if you need more idle fuel by holding a propane torch over the carb at idle and off idle. If the motor is lean the idle will pick up with the extra "fuel" (propane).

Why did you drill out your "idle mixture screws"?

 

damn f-bird, you're a month late

I kinda goofed in assembly there. I now run 24* base, 12* mechanical, 16* vacuum IIRC. Seems to be good.

I drilled out the idle mixture screw holes, as Roe said it's a good first step, to drill them out to the size before emissions, 3/32". That way you have adjustability, if you need it.

I'm actually have a crapload of carb tuning problems now, if you want to read about my escapades, check out this thread:
https://www.thirdgen.org/forums/carb...-jets-non.html
i'll update it now, on my progress today...