blackbeauty74

Its needs to be rebuilt or replaced.

straub18045

cant tell by your sig. what kind of engine or whats done to it, in your vette. but would recomend rebiulding it with gm parts.

TopGunn

I agree also, these HEI's sure beat the heck out of the point setting/dwell routine.
Only problem I've ever had is having TWO "buttons" fail that bring the juice from the coil to the rotor. Drove the car into the garage at night and the next morning no spark. I just replaced the button. I've spoken to other guys who've had the same problem; I've never been able to figure out why

Superstock

I ran a small cap HEI conversion / an MSD blaster coil over 20yrs. ago in a 9.50-9.60et 454 bracket camaro . The same dist./coil has been in my 73' vette 454 for many ( lost count ) years . A few hundred of 6000 rpm blasts. When it was in the camaro it saw 6500-7000 rpm . And one weekend ( a mistake ) it saw 8000 rpm with a 5.38 gear crossing the stripe . Put the 4.88 back in Monday after that weekend. ha!

69427

I'd be interested in some more info on that conversion. I've converted several older distributors to electronic switching, and I'm always interested in what other guys have been doing.
TIA.

69427

How exactly does it do that?

noonie

Thanks for the explaination. Seems like GM came up with a perfect solution for their needs and then some. No wonder I've been so happy with it over the years.

I also didn't realize Gm manufacturing was into silicon.

Somewhere, I got the understanding that the GM module output was 5v to the coil whereas the msd module is 7.5v (maybe got it from msd advertising). Maybe that's what forvicjr is referring to, but the no free lunch scenario should still apply, if the biggest shortcoming is in the coil?

olescarb

IMHO, the msd system (multi spark) seems to help a hot cammed engine idle better (less misfire events) since it has more sparks that will hopefully ignite the poorly mixed/poorly vaporized air-fuel mixtures that are seen at idle and lower engine speeds in a hot cammed engine. FYI, from what i am told GM and Ford tried experimenting with multi spark systems a few years back but because the multi sparks caused multiple flame fronts in the combustion chamber the NOx emmisions of the engines was higher than a "normal" ignition they dropped the idea.

Henry @ olescarb

69427

I'm not sure where those 5 or 7.5 numbers come from. The HEI just runs off of the 12v system voltage.
The coil does most of the hard work, in that it is the one item (in an inductive system) that has to keep "filling up" with energy. Storing energy obviously takes time. It is the energy storage time that is usually the prime speed limitation in an ignition system.

noonie

Memory is failing.

Here is a link that says 7.5 amps not volts.
http://www.msdpower.com/product/part...45.php?cat=ign

69427

Hey Henry,

I see what you're saying, and I can't disagree with your thoughts on this scenario (the NOx issue was something I had never thought of before).
I admit to frequently having difficulty wrapping my arms around some of the reasons I've seen in numerous other threads regarding ignition choices, and the following are just my thoughts and opinions on that. I invite your input on them.
I've heard quite often the claim that the multistrikes help ignite material that didn't light off the first time. I'm somewhat uncomfortable about lighting stuff off at a retarded timing, as potentially happens due to the time/angle lag between the first and second (or third) strike. It is frequently noted that CD ignitions have a short arc time (a well known CDI supplier shows a graph illustrating this), while Inductive systems are known for longer arc times (I'm still trying to get comfortable with the physics that explains this difference). In that graph it appears to show an inductive system that is supplying voltage and current (ie: energy) throughout the duration of the three CD pulses. It just seems to me that for the same length of time, it would be more productive to have one long arc, rather than three short ones, and in particular, what happens at higher RPMs when the CD system goes to single strike? The changeover to single strike seems to occur just below the RPM range that most engines develop peak cylinder pressure and torque. I would expect the kV and energy requirements to be somewhat maximum in this range.


Just a few thoughts and questions from my perspective.

thanks,
Mike

cam cooper

to 69427 i took alot of hits over using something other than a stock hei.u guys did one hell of a job at delco making that setup on one of the best and most copied in the industry and i thank u for that it made my job and alot of others alot easier,i remember setting the duel point and how much better it was after the hei became aval.mostly now we run a crank trigger setup and u know why.i remember my first hei up grade in a circle track car was a accell eliminator conversion on the stock set up and it seemed to help,but maybe that was my imagination.i dont know if u are still in kokomo or not but if u are respond and maybe we can get togather at one of the pulls we have in your area i would injoy meeting and talking shop with someone of your background maybe u could give us some pointers as to somethings to make us better.winning requires experience and knowledge and thats something we could all use alittle more of.if this is is something u would like to do please respond on a private email.thank u

427Hotrod

I really didn't want to stretch the truth....but it actually sneaked a little higher than 7500 rpm!

4.56 gears, 27" tires....sometimes auto..sometimes 4 speed. Regularly 134+ plus trap speeds.

I still have the distributor. It literally came out of a one ton truck with a blocked vacuum advance. Goofy sucker had a plastic lockout plate for the vacuum canister from the factory. Ran great!

JIM

straub18045

a dyno test would be neat, also test a vehicle with the spark plugs with the 6 electrodes.

1980 blue L48

I wish to tell a story about a stock HEI distributor. Back in 1979, I studied automotive at the state vocational college. One of my instructors was an old School gearhead. At School, we had an old SUN distributor machine. I pulled the HEI out of my car, It had come from a junk yard for $10. He mounted it, spun it up to 3400 rpm (6800rpm actual engine speed) and shouted out " this my Friends is why you don`t need any of those fancy aftermarket distributors" , " I just all but hit 7000 with a stock unit, Thats amaizing" It did become unstable at 7000 an above though. Just sayin.

straub18045

(as i stated early on)

jackson

Things change, so I cannot answer for the part numbers being marketed this month because I simply cannot know ... BUT ...

I had/have two Accel Blueprint Performance HEI I'd acquired NEW about ten years back. They are genuine GM cast alum housings. Everything else is NEW. Accel electronics etc have been very good/robust; Accel began as a performance division of Echlin (napa)later forming as Accel. I've sold dozens of asian HEI and I know how the details look/feel different. I believe the NOS Accel HEI described are all USA. I recently sold one to a local racer. I have one remaining at a fair price; email only if serious buyer.

those fleabay asian HEI sell about half what my NOS Accel HEI will.

I even have some NOS Echlin dual-point pieces that're direct ancestors of Accel dual-point ... exactly same in every way even part # ... just different name.

All that said, unless your GM HEI has badly worn shaft/housing, ... it'd be fairly cheapNeasy for most anyone to refurbish your GM HEI ... it's a good piece and it don't take pedantry/tedium to reaffirm that.

olescarb

Mike, I think that the timing of the multisparks would not be a issue as far as retarded timing other than the possibility of multiple flame fronts in the combustion chamber. As for the longer spark duration thought, i think that would be ok but the program to shorten it to a normal time frame at higher rpms would be a issue.

I like the MSD pro billet most for the ability to modify the advance curve (amount and rate) without having to add a mechanical stop for the amount of advance plus i have yet to find advance springs that
will supply a curve that has no advance at idle yet be all in by 2800-3200rpm. If you are interested there is a link to a tech article on my concept of ignition advance tuning at www.olescarb.com where we use the NOx content in the exhaust as a tool for tuning the advance.

Thanks Henry

69427

Henry,

I'll check out your link. Sounds like some interesting reading. I do all the tuning on my engines, and I'm always open to helpful information.
I'm not following your drift in the first paragraph. Can you give me a little more description of what you mean?
thanks

olescarb

Mike, I think that the timing of the multisparks would not be a issue as far as retarded timing other than the possibility of multiple flame fronts in the combustion chamber.
The multiple flame fronts from multiple sparks does create a NOx issue from what i have seen

As for the longer spark duration thought, i think that would be ok but the program to shorten it to a normal time frame at higher rpms would be a issue.

I think that when the spark duration time is extended it will take more coil saturation time which would be a problem at higher rpms thus like MSD going to one spark per cylinder at higher rpms i think there would be a need to switch to a standard spark duration at higher rpms.

I hope this explains better what i am thinking Henry @ olescarb