Quote:
Originally Posted by geezer#99
If your quadrajet with one power piston doesn't like low vacuum, then how did your afb like it. The afb has 2 power pistons.
Your idle problems and low vac are due to lack of timing.
What's your timing curve like?
What initial?
How much mechanical?
How much vac advance?
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It's been a couple years since I checked mechanical and vacuum advance. I don't remember the specifics, but I remember nothing unusual. Initial is 8* BTDC. I've experimented with advancing it, in an attempt to rule out dampener slip, but when I do advance the timing, the engine seems to run better, to a point. When I go on a test drive, after a couple miles, it runs terrible, the idle quality plummets.
I also tried manifold vacuum to try and boost vacuum, essentially, as a way to compensate. But again, once I take a test drive, the idle become more erratic, and performance suffers.
As for the AFB, I did attempt to lean it out a bit a couple years ago to improve economy. Again, I don't have the specifics. I installed leaner rods. Drive-ability suffered. Ultimately, I don't recall how I corrected it, if I used the leaner, or original rods.
The AFB seems to not mind the low vacuum as far as I can tell. It passes AZ emissions. (Has for 7 years!) (It did fail a recent test, because I'd just fixed an exhaust leak on the driver's side manifold doughnut, which affected idle quality once fixed. I adjusted the mixture screw to correct that, the results of the test indicate I went too rich.)
I'll test the timing advance and get back to you.
Thank You for your help.
Regards,
Mike