1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

12a issues

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Old 04-14-10, 10:40 PM
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12a issues

Ok, ive got a 12a that was just put together, street port, custom intake and header, and an Edelbrock carb. Ive finally got it running but I have to turn the distributor cap counter- clockwise for it to start and idle. The cap hold down notch is just inside of the leading ignitor mounting area. Adjusting the dist housing doesnt seem to effect it much and moving the dist drive a tooth either way and it wont run, but barely turning the cap makes a significant difference. The only way I have found to insatall the dizzy is to put eccentric pulley on leading mark, line up mark on dizzy drive with housing then install, and nothing. It idles rough at about 2- 2500 RPM, snap throttle sounds good but holding raised RPM is real choppy, not really in a good way. Any thoughts about timing/ dizzy install or Edelbrock tuning greatly appreciated

By the way changing rods, springs or idle bleeds doesnt really make a difference. And this is in an 88 B2200, swap went great. Any questions? Id love to help.
Old 04-15-10, 01:03 AM
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your dizzy is about 90 degrees off one way or the other.

Way to find the close to correct setting is through trial and error. What I did was connect only the 1st rotor's leading plug (the top one) because you can damage rotors with the wrong distributor setting. Why risk damaging both? Remove the distributor , rotate it, insert so the pinion gear is at different position. And briefly start the engine. It will be obvious when you are getting closer to the correct dist position.

However, the correct way to do this is find the correct top dead center of rotor #1.

When you are close, then you can use the timing light to get the exact position.
Old 04-15-10, 01:41 AM
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Thats basically what I did to get it running ( tooth by tooth), and its at the only possition that it wants to fire on. A tooth either way doesnt work. Wouldnt 90* be close to swapping L1 and L2? I thought the leading was the bottom?

When the drive is moved around it either does nothing, pops loud in the exhaust irregularly or fires where it is currently at.

When the pointer is at the second pulley mark ( L1 correct?) where should the dist rotor be? Right now its pointing about the far left terminal on the leading ignitor. Thanks again.
Old 04-16-10, 08:20 PM
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So nobody knows the proper procedure to install a distributor on a 12a? Tune an edelbrock- not very common, I undersatnd.

Is there any possibility of a wrong distributor cap or distributor? It looks like all the ones ive seen in other pics and other cars.

Ive installed an open carb spacer also. Didnt help the choppy raised RPM but I havent had time to mess with it.
Old 04-16-10, 10:40 PM
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bottom plugs r leading.
Old 04-16-10, 11:36 PM
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t is on top and trailing, yikes!!

so I used the the trailing and not the leading L lower? Lucky me.

Anyway I got mine to run by getting it close. One tooth made a slight difference. Lucky me.
Old 04-17-10, 02:07 AM
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Hmm. So you had wires wrong and dizzy rotor only close and it fired? Im sure I went through all the teeth on the drive and it only fires in the one spot its at after I turn the cap, which still doesnt make sense to me, WTF? I guess 180* it would fire. The mark doesnt change when I use a timing light and move the cap either, but does if I turn the housing. It wont start if the cap is lined up properly, still FM.

Should there be something hooked up to the far left terminal of the ignitor? Everything ive seen about non- factory setups shows no wire on it. I dont see how it would fire but not run right.

Trial and error tomorrow, again.
Old 04-19-10, 01:07 AM
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Well I guess I had the dizzy in the right spot but for some reason only after changing everything on the Edelbrock, making it as lean as possible, it will start and run with the cap in the correct location. Any ideas why I had to turn the cap to get it to start?? And I had a huge vacuum leak but it doesnt run much different surprisingly. I think my main problem is the carb. Im gonna find a 500 CFM Edelbrock since it doesnt look like there is room near the inner fender or firewall for a Holley. Im using a 750, I know its huge but I thought it would run a little better. It just cuts out completely with a little throttle under even a slight load like slipping the clutch just to start moving. Once the trucks moving enough and the RPMs are up it revs ok but feels very low on power.
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