Join Date: Oct 2000
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Adjusting carb (continued)
I decided to make another post, because I went off the original topic and it went two pages.
I've had bad vibrations at idle, and have found it to lie in the adjustment of the carb.
A little info
It's a 1986 4.3L from a k10 blazer
It has a new qaudrajet carb from a late 70's model chevy pickup.(w/a 350)
I've also just set the timing to four degrees(I don't know if this is correct, someone on board said it was 4 degrees a few months back)
It has an auto tranny
LEVE gave me a method of turning in the screw until it drops 100 rpm, then readjusting the idle.
Repeating this until I can no longer drop the 100 rpm.
I have done this, and it will drop that 100 rpm after a turn or two until I have the idle mixture screws ALL the way in, and my idle speed very high(screw is very hard to turn)
I then adjusted out one turn, and it diesels like crazy, and the idle is way too high.
I've also been told to use a vacuum gauge, which I have purchased.
I've been told to adjust it until I can get the highest reading.
If I richen it, it will continue to go up(to and past 26hg).It doesn't stop increasing, and my idle mixture screws would almost come all the way out.I don't want another fire, and I'm thinking fuel will leak out, so I didn't fully unscrew them.
My main problems seems to be that I have to variables, and I don't know how to eliminate one.
My vacuum increases as my rpm increases, either I can richen the mixture, and lower the ilde speed, or lean the mixture and increase the idle speed.I get the same results, and they are two different settings.
I'm just totally baffled..I hate to make another post but I need to go to work tomorrow, and I'd like to be able to drive on the highway, and start it up without any problems(its very hard to start right now)
I don't know if it matters, but I am currently 2 1/2 screws out on my idle mixture and when I put on my air filter, RPM increase about 150.
I've borrowed a timing light, and an inductive engine analyzer(has a tach among other things).
If there are any test I need to do, tell me.