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Discussion Starter · #1 ·
It it well worth an upgrade to a GM HEI? or is the stock one adequate? I also noticed there is quite a bit of play in the rotor, I can turn it
it 1/2" one way or the other when the engine is off. Also, what should I set the timing to for the best performance on a stock 304
motor, run on 87 octane.

 
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Discussion Starter · #2 ·
if its a points setup (it is right?) you will gain a fair bit by going to an hei, if yours is electronic already I wouldn't bother. the distributor shaft can move around a bit when you turn it by hand and its not a big deal, there is a centrifical advance mechanism under the rotor that allows it to move around, and the shaft will move a bit the other way cause you are turning it backwards, when the engine is running the action of the cam gears will pull the shaft down and keep any play from being a problem. run the stock timing, you'll stay out of trouble that way.

 

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Your '75 should be already equipped with electronic ignition. The GM HEI only fits the 258 6 cyl engine. There is an HEI type available for the 304. I think it costs about $300. I'm not sure how much better it works than original. I think it's mainly better in higher RPM situations, but I'm not really sure. If you have the old points type ignition, it would be much better to go HEI.
The play in your distrib is normal, unless the shaft wobbles from side to side. I should turn maybe a quarter of a turn so the vacuum advance will work.

Loose nut behind the wheel
Another right-wing conservative.....
 

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/wwwthreads_images/icons/tongue.gif Im my not so humble opinion, the GM HEI conversion for the 304 is money well spent. Our 304 powered CJ is apart right now, but when it does fire up it will be with the newly devloped Davis Unified Ignition system which sports all GM parts. I am always leary of stuff that requires the driver to carry a spare this...or that...like the Motorcraft breakerless does, and it does have a lot of other little items to shepherd....the two connections to the brainbox..the long, resistance-specific feeder to the coil...plus the pickup module itself. I just trust the GM HEI a lot more IN ADDITION to the increase in fire that it offers. The achilles heel of GM HEIs is that if you sluff off and let the plugs get real bad...OR let the wires get real bad, it will blow through the rotor to ground/wwwthreads_images/icons/frown.gif but, whose fault IS that?/wwwthreads_images/icons/wink.gif

CJDave
 
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