Mallory Unilite
Accel Electronic
MSD
GM Performance

I am leaning towards the small headed distributors with external coil since I just bought a set of 8.5mm spiral core wires. Any input would be appreciated.

I am going to buy the pick-up and reluctor for mine while putting pennies in a jar for a new distributor.

If you think I should go with the big headed HEI, let me know that too.

Have a look at these.... Good stuff, and they set it up specifically for your application...:)
http://www.performancedistributors.com/gmssdui.htm

I bought a fast burn 385 crate engine from GMPP, it came with an HEI distributor. I changed it to one from Davis Unified Ignition (D.U.I.) and it made a 19hp Difference at the rear wheels according to the dynojet Chassis dyno.

I am leaning towards the small headed distributors with external coil since I just bought a set of 8.5mm spiral core wires. Any input would be appreciated.

That is what you want to do.

That is what you want to do.
This is an interesting thread. I have a small cap dizzy and external coil from a Holley Stealth Ram conversion that I was doing (using a TPI computer) and was considering ditching it for a D.U.I. unit now that I'm going back to a carb setup. Rick, why do you recommend the small cap and do I need anything special to make it work (I'm pretty ignorant when it comes to ignition)?

Over the past 1.5 years we have done many back to back HEI versus small cap and external coil tests on various motor combinations. The HEI setup, no matter if it was a stock type GM, MSD or brand X never, ever made the torque and HP of a MSD small cap distributor. It's not a difference in springs, weights, timing curve it's has to be a difference in spark energy.

To us it's one of those no brainers. Want to make more power across the curve, ditch the HEI.

We don't do anything special, just hook it up with the springs and weights we want for the application.

anything BUT Mallory, what piles of junk....

Can you swap an HEI distributor to small cap just by replacing the cap?

Over the past 1.5 years we have done many back to back HEI versus small cap and external coil tests on various motor combinations. The HEI setup, no matter if it was a stock type GM, MSD or brand X never, ever made the torque and HP of a MSD small cap distributor. It's not a difference in springs, weights, timing curve it's has to be a difference in spark energy.

To us it's one of those no brainers. Want to make more power across the curve, ditch the HEI.

We don't do anything special, just hook it up with the springs and weights we want for the application.
Are you refering to the 1987 and up dizzy's (small cap HEI's)? Because that's what I'm stuck with right now.

I'm going to move this to engines, as I think the discussion will be even better.

and was considering ditching it for a D.U.I.

I'm running their large cap EFI distributor for the last few years. Works great for my purposes.

I thought it was either or. Now I get the impression that a large head HEI with a coil on top is general purpose, drop and go. Performance wise, small head with an external coil is better.

My P.O.S. Accel (not working yet) has mechanical and vacuum advance settings, both of which can be tuned to your specific wants/needs.

MSD is a runaway so far in the poll.

I voted MSD.
My experience is with Mallory Unilite, Comp 9000's, MSD, & of course HEI's.

I used to run a small cap unilite way back many years ago. Fried the pickup, which was the biggest problem with Mallory's. I had a couple of Comp 9000's that were great distributors until the eye's went out on them.

Now I've got an MSD 85551 (IIRC) that's had a large cap conversion, I bought it used like that. Worked great when I used it, I need to replace the cap before I put it back to work, current one has a crack.

Right now I'm running the old reliable HEI, best choice for a stock type engine IMO. Once I get the new engine built, I'm pulling the MSD off the shelf and putting it back to work.

My P.O.S. Accel (not working yet) has mechanical and vacuum advance settings, both of which can be tuned to your specific wants/needs.



I have the electronic Accel also. Works fine once you get it tuned to your needs. To tune the machinical advance you have to take it out of the engine and take it apart to get to the springs and weights. A PITA if you're trying different curves. Once I got it right for me it's worked fine. I ran it for a few years with the module it came with and later with a MSD 6al box...no problems either way.

Are you refering to the 1987 and up dizzy's (small cap HEI's)? Because that's what I'm stuck with right now.

Nope, going from a standard type HEI or MSD HEI to a MSD Pro Billet standard distributor (85551 or 85561) with a remote Blaster coil.

had good luck with the GMPP dizzy HEI... not so much with the billet MSD e-curve.

I'm running the pertronix flamethrower

If I was going to do it again, I would of got that electronic msd with the 10 preprogramed curves instead of my probillet...:bowtie:

Stock HEI here, with Proform upgrade kit.

I like the MSD dist for a couple of reasons
1) The magnetic pickup/module is tough and unaffected by dirt and grime unlike the Mallory Unilite setup.
2) Most dists have a series of bushings that the shaft rides on. Over time these wear out and the shaft starts to wander and do goofy things. MSD dists ride on roller bearings instead of bushings

i like the mallory unilites and they're a very good quality distributor ,i can't understand why people hate these . all i ever hear is :whine: :whine: :whine: :whine: my module burned up:whine: :whine: and it's not the distributor it's the cars electrical system F'n it up . you have got to make sure that your electrical system is up to par before installing one .the main culprit is ground dumping that usually happens on start-up or shut down . if your alternator is bad it'll cause a voltage spike thru the grounds that will kill the module


you need to make sure your grounds are suffient enough and there's good continuity thru-out the entire chassis,body and engine .also it's a very good idea to run a voltage spike protector inline with your unilite to further protect it . that is called the mallory active power filter part #mal-29351 .you can also use mallory's #mal-611M power cell as a filter and that also works well .in order for these to work at there best you need to make sure the ground wire from the distributor goes directly to a good chassis,engine or body ground .also when using the mallory power cell #mal-611M use one side of the two wires provided and run it to the chassis ,engine or body ground source

now the modules if you don't know where to look for them or know the correct part #'s the module will cost you $89.95 .but if you use the module for the conversion kit which is exactly the same as there standard module # mal -605 $89.95 the conversion module # mal-6100M is only $37.95


here's a few example of what kills the modules :

stuck or shorted regulator or alternator

faulty starter causing excessive amps

non suppression style plug wires

to large of amperage alternator

ineffective chassis,engine and body grounds

direct shorts in the cars electrical system

faulty or improper grounding of the unilite


what usually happens is if you electrical system is not up to par you will get voltage spikes up the ground wires upon engine start-up or shut-down and it'll kill the module


another great site that knows alot about mallory ignitions is http://www.centuryperformance.com you need to email sam solace as he's the resident guru of mallory ignition systems

Looks like MSD was the overall dream crusher.

Muscl - thanks for the tips - I changed my ground (and the module and pick-up). It seems to be firing O.K. now.

Im very happy with the good ole HEI and an MSD digital module w/ rev limiter, keeps it simple in case I get stranded.

I have sort of a hybrid GM/MSD setup. I run a GM HEI with an external MSD Blaster 3 coil, and a MSD Digital 6+ box. Works very well, no complaints.

I use old points type dizzys and replace the points with Pertronix or Crane XRi modules. I prefer the Crane as it has a built in rev limiter. Blaster 2 for coils.

The HEI style is what every GM crate engine uses for their dyno tests, so its good enough for me. ChevyHiPerformance did a HEI test and found:
"While high horsepower supercharged and nitrous-equipped engines can always benefit from those mega-power CD ignitions, most street engines can employ a quality, high-performance HEI ignition without fear of losing power to a weak ignition. Combined with a well-designed spark curve, quality spiral-wrapped plug wires, and the proper heat-range spark plugs, it’s possible to ignite up to 500 reliable horsepower with little more than a hopped-up HEI distributor."

My Mallory Pro-billet just exploded the whole advance mechanism. Total failure. It's only 18 months old.

My Mallory Pro-billet just exploded the whole advance mechanism. Total failure. It's only 18 months old.

and you remembered this poll from last year?

the guy i bought my car from put in a summit dist. obviously summit doesnt make it, who does? he atleast gave me the part number and all the extra dist. springs.

I bought a fast burn 385 crate engine from GMPP, it came with an HEI distributor. I changed it to one from Davis Unified Ignition (D.U.I.) and it made a 19hp Difference at the rear wheels according to the dynojet Chassis dyno.
Wow.

Stock HEI for me right now, and I've never had any problems.

I voted MSD only b/c I have one. Used an HEI on my old 87 IROC w/ a mild 357 SBC and it didnt seem to have the power.

Only problem ive had w/ it is the springs broke and the car stopped running (duh).

hei with a jacobs amp.

Ive been running a hei all my life because its simple and im stupid! lol mine has msd everything with rev limiter

camaro still has the points dist.
The chevelle had a swapmeet HEI, when the thing ran like a pig, we put a timing light to it and found only 8* mech. adv! switched to a mallory magnetic mechanical adv. dist. car ran great, but decided to swap to a MSD streetfire, so I can get 20* mech. and a vacuum advance! jim

I didn't "remember" this post; I found it while searching for opinions on a replacement. Ended up with an Accel Billetech as recommended by a close friend and NHRA divisional competitor.

I like and ran a MSD small cap dizzy on my previous tunnel rammed engine and run another MSD small cap dizzy on my 671 blown engine. The only set back was that I wish they included more advance bushings. I was limited to the blue, silver, red and black bushings and also had to run an external box. Since the motor is exposed to the elements, I had to drill holes in the dizzy cap as moisture would cause white deposits. If I could fit a modified HEI, that's what I would install.

While you guys are on the subject.....what's the life expectancy of an HEI coil and module?.....in other words would you notice a difference between a fresh new coil and an old one like you would with new and old spark plugs and wires?....curious.