Question for HEI Ignition Users

[Costello]

Does anyone have experience with HEI Ignition takking a dive at higher RPM's? What kind of RPM are you guys seeing out of the stock module and coil?

[Oldsquirt]

Costello, I have read that a stock HEI can start showing a coil output drop at as low as 4500 rpm. MSD makes a module(#8364 - 4-pin style) that is claimed to be good up into the 9000 rpm range. I believe I have also seen other aftermarket ignition modules that will do the same thing.

[Costello]

OldSquirt, I have run Mallory Comp 9000 and MSD 6al with Pro Billet on my previous rides. Both good systems. This HEI thing is kinda by default. I have heard the same thing with around 4500 rpms the HEI fall apart. Others have told me they ran 7000+ with them. My deal seems to fall apart about 4800 RPM with the stock components. I'd planned on stepping up to the MSD or Pertronix HEI coil and module, but wanted to see what the others experiences were here before I throw more money in "the pit". http://free.***boat.net/ubb/smile.gif

[Costello]

Oldsquit, as a side note, look how close our IP adresses are in the previous posts. Freaky!!

[Oldsquirt]

Yeah, those IP addresses are damned close! I hope we aren't going to be accused of being each other http://free.***boat.net/ubb/biggrin.gif
I think if I was going to run an HEI distributor, I would put in an aftermarket module as the first modification. I haven't had a GM ignition system on a scope in a very long time, but I do recall that dwell time(and therefore, coil saturation) decreased considerably at higher rpm. The MSD one costs $65 at Summit. A stock GM module goes for about 1/2 that, so its not a bad price if it performs as claimed.

[JEThro]

Costello,What do you mean by taking a dive? Check your advance mechanism. The plastic bushing in the weights might have worn away causing the holes to become oval. This will give you eratic timing at higher rpms.

[Costello]

JEThro, it sounds like it's on a chip and dropping cylinders. You have to pull out of the gas and let it recover before you can roll back into the pedal. It's not a fuel issue, as I have run 3 different carbs on it in the last couple of months. I'm thinking this HEI is crapping out at that RPM range.

[flat broke]

Costello,
They do die out around 4500-5000. To counteract it I did the following for the sbc in my chevelle. Ran the Mallory upgrade module and an accel in the cap coil. The thing will hold 6500 for extended periods of time and I know its good up to 7000, but I haven't had many chances to test its duration at that RPM.
Good luck,
Chris

[Costello]

Thank you Flat Broke. I'd heard the same, but I know others who say they are good to high rpm's. (Probably with the module & coil upgrade) Mrs. Costello will be pleased that more of her hard earned can get tossed into the money pit. http://free.***boat.net/ubb/smile.gif

[wsm9808]

I,ve got a bone stock HEI in my sb Camaro and it spins to 7000 with ease and never misses a beat, and also Have an HEI in my boat with an Accel super coil and cap and it runs flawless. I,ve always heard the HEIs wont rpm, but I,ve never personaly had any trouble from one. But its possible yours could be acting up. http://community.webshots.com/user/wsm9808
[This message has been edited by wsm9808 (edited May 29, 2002).]

[Costello]

wsm9808, What I have gathered from a few other sources, is that some of the actual GM modules are pretty decent. It is the CSK, Autozone, Pep Boys, etc. aftermarket type that really choke around 4500-5000 rpm. The one in this distributor I have was from CSK, a Niehoff. I put in the MSD module today and am going out tomorrow to see how it works.

[Wet Dream]

Just a note on my 455 with HEI, I have turned the thing to 5300 rpm and never noticed a skip. At a high rev cruising 4600, I can romp in it and get 5300 out the door. Just thought I would let you know what mine was doing.