Pertronix vs HEI - Page 2 - Chevelle Tech
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post #16 of 23 (permalink) Old Aug 19th, 09, 10:15 AM
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Re: Pertronix vs HEI

Awhile back,I removed the HEI and went back to the stock points distributor.
I wanted the factory look...I am no longer a fan of how an HEI looks in a vintage GM musclecar unless its 1975 or up
An HEI is a great unit,no complaints here.
I converted the points dizzy over to electronic using the Crane XRi "brain" (Crane brain for short )
Anyway,works difference in performance either.
And for a back up,I have a spare brain in the glove box. Darn things are cheap enough.
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post #17 of 23 (permalink) Old Aug 19th, 09, 1:48 PM
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Re: Pertronix vs HEI

Given a choice between ANY aftermarket "electronic conversion" and a DELCO HEI; I'll take the Delco ANY DAY.

Given a choice between ANY aftermarket "electronic conversion" and some cheap-ass Communist HEI knock-off...I'll take the Non-Communist solution--or keep the points; but that's based as much on politics as performance. I'd rather have a "good used" DELCO HEI than a brand-new Chinese junk HEI even if it does come with a "60KV coil".

There's a lot to be said for OEM-level reliability as supplied in a Delco HEI.
If you have problems with the module dying--either you're using a crappy module; or you have some other defect that's killing the module as a side-effect. There's millions and millions of HEI-equipped cars driving around that DON'T have a spare module--or coil--or pickup coil--or whatever--in the glove compartment. But, true enough, ANYTHING can fail; which is why there's a lot to be said for "Replacement parts are available at any parts store in North America", too.

Putting the points back in; and waiting a week for mail-order replacements to show up is not my ultimate solution.

The HEI will SUPPORT a wider plug gap than the points-style ignition. It does not REQUIRE a wider gap. Big difference.

I have had exactly ONE MSD spark-box failure (MSD-5 from about 1978) that I could blame MSD for; the box was about eight years old at the time; and MSD charged me either $25 or $35 (I forget) to set it right. That same box failed again about ten years later (the box was old enough to vote!); but that was my fault; I screwed up. HOWEVER, I keep hearing that MSD has gone downhill as of late; and I've seen some evidence to support that. All I can say is "Be Careful".
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post #18 of 23 (permalink) Old Aug 19th, 09, 3:26 PM
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Re: Pertronix vs HEI

shurkey is right about msd. I put a street fire box in my car thinking I needed it for some reason. it was brand new and no good right off the bat. the msd hei distributor has given me no problems but I do carry a spare gm hei module in the glove box.....
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post #19 of 23 (permalink) Old Aug 21st, 09, 6:22 PM Thread Starter
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which spark plugs?


I am taking the path of least resistance and going with a GM HEI.

The spark plugs for my 1970 engine are NGK 3332 needing a 13/16 socket.
Looks like the spark plug for a 1977 (HEI) engine are NGK 6630.
BUT they are not 13/16 plug socket and do not have a compression washer, they have a tapered end.

What NGK plug do I want to use with my engine converted to HEI?

Thank you,

1970 CHEVELLE SS clone - 350 SBC, 350 TH, 2.73 rear gear

Last edited by 1970; Aug 21st, 09 at 7:29 PM.
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post #20 of 23 (permalink) Old Aug 21st, 09, 7:35 PM Thread Starter
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Which spark plugs for this conversion?

Which NGK plugs when converting to HEI?

1970 CHEVELLE SS clone - 350 SBC, 350 TH, 2.73 rear gear
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post #21 of 23 (permalink) Old Aug 21st, 09, 7:41 PM
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Re: Pertronix vs HEI

Not sure about the NHK's, but I bet you'll be nice and happy with the HEI from GM.


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post #22 of 23 (permalink) Old Aug 21st, 09, 9:00 PM
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Re: Which spark plugs for this conversion?

Originally Posted by 1970 View Post
Which NGK plugs when converting to HEI?
The first thing you need is the right plug to fit the cylinder head. So you're pretty much stuck with a gasketed plug.

You'd probably keep the same heat range.

Next, add a projected tip if there's one available AND if it fits your combustion chamber.

Lastly, you want a plug that would allow a .040--.045 gap.

Depending on the gap--that may (or may not) be the same plug you're using now.
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post #23 of 23 (permalink) Old Aug 21st, 09, 11:50 PM
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Re: Pertronix vs HEI

I have never run a Pertronix, then again I have never had an HEI failure, nor have I known someone that personally had one fail...
like anything, there will be failures, and you always here about the failures, but rarely the "sucess" stories... If the HEI was truly prone to failures, would GM have kept using the design in millions of production cars? Perhaps people running a cheaper quality module are typically the ones having the problems, but cheaper quality parts often do have issues (hence peoples distain of "chinese and other imports junk).

I do agree that an OEM version is probably the best choice. But then again, its still and old used distibutor 9does anyone know if newer Delco HEI's are "US-made, quality pieces? or are they questionable now?

One issue I see with using the Pertronix, is that you are still (most likely) using it on a worn, 35-50+ year-old distributor... I don't know if worn shaft bushings affect the pertronix performance...

As for the Summit HEI, I run the $89 version(no wires, but included a 50Kv coil), I have one in my Chevelle, it has an adjustible vacuum advance cannister. The Mechanical advance curve was already set up right where I wanted it (IIRC, 18 degree Mech advance, "all-in" by 2800 crankshaft rpm). My car has 12.34 seconds (1/4 mile ET) at 110 mph with it... I eneded up using a Summit ignition box (for the rev limiter), so I have no idea how well the Summit-supplied module would be...

IMO, there's also a 3rd choice... Dave's Small Body HEI's (assuming Dave is still doing these conversions)... Dave uses standard HEI parts, but mounts them on your stock distributor (you send a core)... His conversion (IIRC) uses ALL commonly available HEI pieces (he gives a listing of Napa part numbers), and it works with a standard external coil, so it can look fairly stock. It uses the stock "points" cap and stock wires. Dave also fully rebuilds the distributor (chromes the shaft and re bushes it, etc), so its truly like new (as opposed to just new electronics inside an old worn distributor)... Finally, he sets the curve up to work with the engine specs you supply...

He mounts the module UNDER the stock distributor, so you can see it, but you have to look for it...

I used one of Dave's on my old Chevelle, and it worked GREAT as long as I had the car... I was running a Dual Quad intake, so a standard HEI wouldn't fit...

I originally bought my Summit HEI as a temp solution to get a car running that had no wiring harness (just needed one wire). By the time I found a junkyard distributor, new cap/rotor, hope the coil and module are good, etc etc, Ifigured the $89 was a good deal (I was also extremely busy, and didn't have time to scrounge the wrecking yards during the day)... Its worked so well, I bought another ( for the same car/temp solution I bought the original one for)

Once you go RAT, you never go back...
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