HEI vs. MSD

[sgt1022]

I contemplating switching from HEI to an MSD ignition system. My question is would the MSD be a more reliable system?

[truckster]

Have you been having problems with the HEI? GM's factory HEI is an extremely reliable system, so I'm not sure you'll find anything more reliable than a properly operating HEI.

[sgt1022]

just recently. Ignition module went out. Now it was spitting and sputtering like bad fuel. It has new E3 spark plugs which are about 2-3 months old. Gonna change back to ACDelcos and see if improvement.

[Mr Handy]

Originally Posted by sgt1022

just recently. Ignition module went out. Now it was spitting and sputtering like bad fuel. It has new E3 spark plugs which are about 2-3 months old. Gonna change back to ACDelcos and see if improvement.

Double check your grounds. Make sure all are present and in good shape. Every time I have had or seen a module go out it is because of bad or missing grounds... HEI does not tolerate voltage drops.

[Stryder67]

I for one am not a big fan of e3 spark plugs. They are overpriced plugs and I've heard of a bunch of problems with them. And 2x checking the grounds.

[sgt1022]

Just drove home from work. As long as the rpms stayed below 2500 it ran fine.

[Husker]

Use a 12 Gage wire for your HEI. I have mine fused
Ron

[sgt1022]

All grounds are good. This started after module went out. Truck has been rewired with a painless wiring direct replacemnet kit. Replaced E3 plugs with R45ts, which are recommended bt GM for this motor. I replaced cap and rotor while i had it apart with an MSD brand HEI kit. Today was alittle better but still acted funny

[Andy4639]

As far as reliability the HEI is one of the best systems out there for no more money than it takes to install. You want find a better dizzy for the money.

As far as the problems you are having:
#1 what gap is on the plugs HEI say no more than 35-40 no more.
Plug gap

Don't be tempted to excessively widen the gap. The correct gap is 0.035"- 0.040" for the majority of cases. Using plug gaps wider than that is unnecessary when using a basically stock HEI ignition.

#2 Did you put the paste under the module?
Use a heat sink paste (available from Radio Shack and computer shops) on the bottom of the module and be sure the surface of the distributor body where it mounts is clean. The heat sink compound (not dielectric grease) helps transfer the module heat into the distributor body which acts as the heat sink. Failure to do this can lead to an early failure of the module.

[67 chevelle]

If volts drop below 12 the msd has a tendency to not work , heis are better at this , therefore in my opinion , better for street use .

[sgt1022]

Andy, i cleaned the mounting surface on the dizzy. I applied the grease that came with the module. I went with .045 gap as recommended by GM. I havent experienced any voltage drops that ive notice. Alternator is putting out 14+ volts according to my gauges.
Could the capacitor been damaged.

[davepl]

A properly wired, USA-made HEI (ie: not a Chinese knockoff, unless it's a well respected knockoff) should last next to forever.

It's when they're wired to the resistance wire, or to the wiper motor, or nonsense like that which can give them a bad name. Properly set up, the GM ones are bulletproof.

I wouldn't add an MSD, as it's just an extra point of failure. If you have a supercharger, you might need the additional spark energy to jump the gap, but for most motors, there's no benefit.

[sgt1022]

The dizzy is a Speedway motors brand. Allegedly blueprinted. I think it is made off shore though. Tried to get some specs for and they couldnt gjve them to me.

[hjewell2]

Originally Posted by sgt1022

The dizzy is a Speedway motors brand. Allegedly blueprinted. I think it is made off shore though. Tried to get some specs for and they couldnt gjve them to me.

That there is your problem

[RichardJ]

>>This started after module went out. <<

>>As long as the rpms stayed below 2500 it ran fine.<<

First place to look is the wires from the pickup coil -to- the HEI module.

The vacuum advance is constantly tugging on those wires as you were when you replaced the module.

[sgt1022]

Not running the vacuum advance

[JustToxic]

Sounds dumb, but check the all wires plugged into the dist. cap. and make sure the module is connected properly. Ran into that a few times, learned the hard way. As far as HEI or MSD, unless you have a performance engine that needs the extra spark, I'd stay with the HEI. You can do some performance upgrades to the HEI to get more spark out of one. MSD makes a better module, coil, cap, and rotor for a HEI, makes a little bit a difference but not much.

[sgt1022]

Ok. Good point, one of the connectors to the module I thought I might have flipped it.

[Andy4639]

Another minor but very important part is the screws used for the coil and cap. If they are to long they go all the way through and create a path way out so the truck runs rough. Just thinking out loud.

[Mike C]

At least most GM HEI assemblies don't have enough mechanical advance on their own without using the vacuum hooked to a ported source. Also check and make sure that your mechanical advance is not stuck.

What is your total advance and what is the rate it comes in? You may just need more total advance. That too fits with some of the problems you seem to be having.

As far as reliability, I'd say 6 of one half dozen the other. But in terms of cost and ease of replacement parts, HEI for the win. FWIW, I run both. I have an MSD ready to run small cap in my Jimmy, an 8560 with a 6T in the Camaro, a couple of of the Street MSD HEI and a tach drive 6AL setup on my 'vette.

They all work great. But the HEI a fraction of the cost. My '69 short step running a Chinese knockoff HEI for $59 going on several years and several thousand miles.

[GASoline71]

What year truck is this in? Did you convert a 67-72 rig with an HEI? Did you use the old stock points style coil wire? If you did, it's a resistor wire and will cause problems with the HEI. Did you gap your plugs to .045 for use with an HEI?

Gary

[sgt1022]

Yes i converted my 71 c10 custom deluxe to HEI. i have 8mm Accel wires and Delco plugs gapped to .045.
Strang thing, while driving home thus afternoon the truck ran normal, no missing even under load

[GASoline71]

Where did you wire in the power wire for the HEI?

Gary

[sgt1022]

I re-wired the whole truck with a painless kit. The power for the HEI was in the harness

[GASoline71]

Sweet. I read you did a Painless kit but wasn't sure how the wire came to the HEI.

Gary