Should you replace HEI module ?
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 767
Likes: 1
From: Noble OK
Should you replace HEI module ?
I recently purchased an 86 Corvette with a slightly modified motor(AFR Heads and Accel Super Ram Plenum and Runners). I bought a new dist. cap and bug for it as the other looked stock and very old. Was wondering if replacing the HEI module with something like the MSD unit is of any benefit or a waste of money. Thanks for any info
Team Owner
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Re: Should you replace HEI module ? (vinnies87)
Your superram allows your car to breath at a much higher RPM level than the stock TPI ever would. While you have not quite hit the edge of the stock HEI system going to an MSD HEI in-cap coil may not be a bad idea for a littel insurance. If you do go this route be sure to also get the low-reisistance HEI bushing that MSD offers also.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Should you replace HEI module ? (scorp508)
Your superram allows your car to breath at a much higher RPM level than the stock TPI ever would. While you have not quite hit the edge of the stock HEI system going to an MSD HEI in-cap coil may not be a bad idea for a littel insurance. If you do go this route be sure to also get the low-reisistance HEI bushing that MSD offers also.
I've never run one, (so I don't have any personal experience) but one of the catalogs cautions against using it.
GM and Accel also specify only a certain coil be used too; depending in the color of the wires on the pickup coil.
Jake
Team Owner
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Re: Should you replace HEI module ? (JAKE)
I've read a caution about using the low resistance bushing, that it can cause problems with the digital tach.
GM and Accel also specify only a certain coil be used too; depending in the color of the wires on the pickup coil.
Burning Brakes
Joined: Feb 2000
Posts: 824
Likes: 2
From: Camden SC
Re: Should you replace HEI module ? (scorp508)
Benefit vs waste of money.
Basically, it's a switch. If it continues to perform as designed, the pistons will do their thing. Some folks carry a spare for no start conditions. I seriously doubt you will see any performance gain. Determining when a solid state electrical component fails is a task I've left to probability. I'd spend the money on a fuel pressure test gauge thereby insuring reliable fuel system operation for several years. Buying a special tool generally means you'll never use the darn thing.
Enjoy the ride.
dlmeyers 90 coupe zf6 3 speed shocks
Basically, it's a switch. If it continues to perform as designed, the pistons will do their thing. Some folks carry a spare for no start conditions. I seriously doubt you will see any performance gain. Determining when a solid state electrical component fails is a task I've left to probability. I'd spend the money on a fuel pressure test gauge thereby insuring reliable fuel system operation for several years. Buying a special tool generally means you'll never use the darn thing.
Enjoy the ride.
dlmeyers 90 coupe zf6 3 speed shocks
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Racer
Joined: Jul 2001
Posts: 322
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From: Los Gatos, CA
Re: Should you replace HEI module ? (JAKE)
I ran an MSD coil and a bushing in my 90 - for about a week. The coil basically fried in no time. Stock coil back in and no problem. Put stock bushing back in too, but I don't know if that had any negative effect or not. In theory the stock bushing is just extra voltage drop you don't need.
I replaced a module as well, but never noticed any difference. Now I have a spare...
Good luck
I replaced a module as well, but never noticed any difference. Now I have a spare...
Good luck
Team Owner
Joined: Mar 2000
Posts: 83,381
Likes: 87
From: Boston, MA
Re: Should you replace HEI module ? (2manyfuncars)
I ran an MSD coil and a bushing in my 90 - for about a week. The coil basically fried in no time. Stock coil back in and no problem. Put stock bushing back in too, but I don't know if that had any negative effect or not.
Safety Car
Joined: Feb 2000
Posts: 3,771
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From: MANDEVILLE, LA La
Re: Should you replace HEI module ? (scorp508)
What really helped mine was installing a Holley Super Pick up module, Petronix HP Coil, Low Resistance MSD Bushing & MSD Super Conductor Wires.
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Re: Should you replace HEI module ? (scorp508)
I've read a caution about using the low resistance bushing, that it can cause problems with the digital tach.
No problem with mine. :)
GM and Accel also specify only a certain coil be used too; depending in the color of the wires on the pickup coil.
Doesn't matter in the vette from what I've seen. The wires on my MSD are white and red and it works great.
No problem with mine. :)
GM and Accel also specify only a certain coil be used too; depending in the color of the wires on the pickup coil.
Doesn't matter in the vette from what I've seen. The wires on my MSD are white and red and it works great.
It's also comes up from time to time on other forums as well. There must be a reason that the pickup coil and the igniton coil must be properly matched; some have suggested it's polarity issue.
Advertisements for the low resistance bushing also caution that it may cause tach manfunctions; that certain tachs need the high resistance to function properly.
Jake
