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Discussion Starter #1
I replaced the dist in my car with HEI,but it breaks up at 3000,summit sells a gm replacment one that is curved,the one in there now...I don't know what it came from.A
friend of mine bought one for his corvette
and loves it,any ideas. al

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Vendo396
 

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Have you got 12 full volts going to the HEI when the key is in the on position.Alot of times they are wired up off the lead for the coil, and only get about 9 volts.If not, run a lead off the fuse block that has 12 volts when the key is on.A friend of mine has the same problem with his Camaro,it breaks up. The above fix repaired it.

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1972 Malibu (1 st. car) Project waiting to happen
Team Chevelle # 427
A.C.E.S. # 1282
 

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Discussion Starter #3
I have it wired to the fuse box when the key
goes on.

<BLOCKQUOTE>quote:</font><HR>Originally posted by Doug Garland:
Have you got 12 full volts going to the HEI when the key is in the on position.Alot of times they are wired up off the lead for the coil, and only get about 9 volts.If not, run a lead off the fuse block that has 12 volts when the key is on.A friend of mine has the same problem with his Camaro,it breaks up. The above fix repaired it.
<HR></BLOCKQUOTE>
 

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But do you have 12 volts at the HEI connector? Keep in mind that the original Gm installations used very stout wiring to supply the HEI with power; 12 gage or maybe 10 gage. Also, if your HEI is old it may need a new pickup coil as the wires on the pickup break after years of flexing.
 

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Discussion Starter #5
I will check this week its about 22 deg outside right now,thurs is supposed to be 40
<BLOCKQUOTE>quote:</font><HR>Originally posted by JWagner:
But do you have 12 volts at the HEI connector? Keep in mind that the original Gm installations used very stout wiring to supply the HEI with power; 12 gage or maybe 10 gage. Also, if your HEI is old it may need a new pickup coil as the wires on the pickup break after years of flexing.<HR></BLOCKQUOTE>
 

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hey vendo why do you keep reposting the replys? I feel like deja vu all over again..

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70 chevelle ss396 conv
66 chevelle ss396 hdp/conv
55 chevy prostreet
 

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Make sure you used an HEI from an early model year. You want one with the vacuum advance chamber hanging on the side. Later HEI distributors rely on an ECM to control timing advance. We just solved that problem for someone here a short time ago.
 

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Discussion Starter #8
yep it's from and older car...don't know what
The mech advance was frozen,it works fine,but
I think it's electrical myself.
 

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Electrically, it could be a few things. Pickup could have a layer short, which would give intermittant spark at higher engine speeds. Pickup ciol leads may have broken strands and disconnect at higher engine speeds. High tension coil could have layer short and is not conducting properly at higher rpms. Connections dirty. carbon post has too much resistance and/or is installed incorrectly. Low voltage feed into the HEI, high resistance in the plug wires, low alternator voltage output, and more.

Also, too lean, wrong curve in the mechanical advance, blown or wrong vacuum advance for the application, too much mechanical and vacuum advance for the engine.

Just some things to check out.
 

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GM part number 1894379 Shaft is the mainshaft with mechanical (centrifugal) advance mechanism from the ZZ4 350 HO engine. I paid about $60 from the local Chevy dealer. You can drop the new mainshaft into your old distributor and have a NEW not worn out advance mechanism with the bonus that it already has a performance advance curve built in. It even comes with a new rotor!
 

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Vendo, instead of buying one off the shelf "curved" to who knows what app, have someone like Ignitionman build you a custom one. I know the guy in our area charges $175 for an custom curved HEI and $155 for a Pertronix equipped small base. But things are cheap in Buffalo! A custom curve is a much better deal than out of the box IMO.
 
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