283 running rough

Hey Fellas, I'm working on my buddies 57 Chevy Belair and he said that he recently had his engine rebuilt.
The rebuilder didnt put in a new distributor cap so we replaced the cap and buttoned everything back up. It was a little out of timing so we used the timing light and set it to 6 degrees advance. It's still runs like crap and sounds like its missing. Turns out that cylinder 3 and 5 are not firing at all. When we took it for a test drive, it shifted hard thru all the gears.

1) Should we set the timing without the vacuum advance hooked up?
2) would a bad vacuum modulator cause a bad idle. Only mentioning it because of hard shifting.
3) do you think new plug wires will do it. Some of them would shock me to the touch.

Thanks guys


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First of all, find out why its not hitting on the given cylinders, run a compression check, this will make sure that the issue maybe outside the ignition system.
As for your question, yes you set the timing with the vacuum advance disconnected and plugged, it should be reconnected after the timing is set to a full time manifold vacuum source, one that pulls vacuum full time including idle. Shoot for 12 degrees before top dead center with vac advance disconnected. Reconnect vac advance after setting, recheck timing, the new setting should be 18 to 24 degrees before top dead center. When you connect the vacuum advance its going to idle up so be prepared to reset the idle and the idle mixture there after. The rough idle is likely caused from it not hitting on 2 cylinders plus the low spark timing.

yes set timing with vac adv disconected
trans should be hooked up to vac source or it will shift hard
yes change wires and check firing order

good luck

thanks guys, I figured that it might be something like that. The guy who did my buddys trans did a really sloppy job, so I'm going to change his vacuum modulator and hose.

As for the timing, I'll go at it again this weekend, one of my buddies told me to do a compression check too, but I'm gonna check again to make sure for certain that they aren't sparking.
I mean I worked with plugs a long time and never been shocked by touching one. I think that he needs a new set of plugs because the spark could be jumping thru the cheap insulation.

thanks fellas

What type of ignition does it have. If it is an original point distributor, check the point gap before messing with timing. Should be .017 or if you can find a dwell meter 28-32 dwell.

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Chet

That's part of the initiation, you don't know what your missing!

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@ t-bucket23 It is an original points distributor. I never really figured out the whole points things any of you guys feel like giving me a quick run down on how thats done? I mean I know a little something, but mostly just bolt on and go type of stuff.

You need to get the rubbing block on the points on one of the highs on the cam in the distributor. The points need to be set at .017-.019.
More that .003 in either direction and it will run like crap as the coil charge time will be to short or the field collapse will never completely happen. Both causing weak spark. It is not hard if you know how to use a feeler gauge.

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Artificial Intelligence is no match for Natural Stupidity



Chet

Make sure the condenser is in good condition or you will get a weak spark.

I have a 32 blade feeler gauge so I'm going to pull it apart this weekend and take some pictures so I can accurately identify the parts your talking about. It's time for me to stop running from this!!!!!

@ lg1969 Yeah the condenser is new, actually all the parts in the distributo are new, which is why I'm thinking that the points need to be set.

Cat, No offense but the best place for points is the trash. There may not be room for a HEI or if the desire is to keep the appearance as authentic as possible then I would get a points conversion kit then you can throw the points in the trash. The conversion unit fits right under the cap, gives you just as strong a spark as a HEI does with no hassle with no gaps or dwell adjustment. Check it out at this link:
http://www.pertronix.com/prod/ig/ignitor/default.aspx

FEELER GAUGE?!?!? I always used a matchbook