The Stovebolt Site Forums The Shop Area The Electrical Bay New Wiring Harness...question about HEI

Hey guys,
My '66 C-10 has a I6 250 out of a 1974 Nova in it. One of my winter projects is to put in a new wiring harness and I'm going to convert over to an HEI at that time. My question is this, what all do I need to convert in order to go to an HEI?

I'm looking at this distributor: https://www.summitracing.com/parts/pro-67081/year/1974/make/chevrolet/model/nova/submodel/base

Does anyone have any better recommendations?

I should mention that I have in my possession the Classic update harness from American Autowire, 500560. According to AAW it should support the HEI.

The '66 C-10 wiring harness has a resister wire which feeds the coil for the points-style distributor. You do not want to use that wire for the HEI distributor. You need full battery voltage.
You may be able to purchase a wiring harness for a '66 C-10 which is constructed specifically for an HEI distributor. That would make life a lot simpler. If not, all you need to do is run your own wire from the ignition switch to the coil on the HEI and remove the resister wire all together.

I'm going to overlook your distributor choice. That's up to you. Others here may have suggestions about that question.

However to change from points to HEI you need:
12 volts to your distributor all the time---and this is very important. Remove the ballast resistor or any resistance wire that might be in your wiring harness. We don't know what you have since around 1971 GM started using resistance wire instead of an inline ballast resistor and if you buy a new wiring harness you might have either resistance wire or you might have an inline resistor. Points distributors use 12 volts when cranking but run at 9.3~9.5v. A constant 12v would burn points up. Your HEI won't work at the lower voltage.

Add (or make certain you have) a good 12 gauge wire from your ignition switch to your coil or to the Bat terminal in the distributor cap.

Here is a tip from personal experience. If your ignition switch is not stout enough to handle the current draw (at startup) of the HEI distributor, don't flirt with trouble. Some ignition switches will just flat burn out if subjected to the increased current. Ask me how I learned this would happen. If you're not certain, feel free to add an inexpensive Bosch-style relay between the 12 ga wire (coming from the positive terminal of your battery or the starter) and the bat terminal of your distributor cap or your coil (if the coil is separate from the distributor). Then use the ignition switch to activate the relay. I promise you'll never burn out an ignition switch by doing this and a new ignition switch will cost more than that Bosch-style relay.

Now, install HEI coil and plug wires, plugs for the HEI and gap them correctly---.40 to .45inch

That's about all that comes to mind. Good luck.

Sorry Carl...I think we were typing at the same time.

Jon, I'm not sold on any distributor as of yet, this was one that I was looking at. I'm not certain exactly what I should go with, I'm certainly open to suggestions and would actually prefer to hear some suggestions from you guys. I'm pretty much a newbie at this.

I appreciate all of the points that were made. I should have mentioned up front that I have in my possession the Classic update harness from American Autowire, 500560. According to AAW it should support the HEI.

RUN- - - -do not walk away from that overpriced, overseas-made distributor. Find an OEM distributor on Ebay or in a salvage yard, and rebuild it with a "new old stock" module and pickup coil, and make sure the centrifugal and vacuum advance systems are in good shape. You'll spend less money, and have a better, more reliable distributor. Ditto on the Bosch type relay and heavy current wire. I use a 60 amp capacity relay, mostly because the wire gauge in the stub harness that comes with it is heavier than the 30 amp version.
Jerry

I Quadruple the OEM distributor! I swapped my smoked unit for a FLAPS model and ran a separate wire from the ignition switch to the Distributor.

Just buy a brand new HEI for a 1975 and up Nova 250. A universal harness supports HEI. CARDONE 841692 seems to be a good one. Probably the only way to get an actual OEM Delco is from a donor. Ebay etc.
OEM is a loose word. These parts are obsolete, so you can't really buy a new one. Just mostly copies. If you get a used one with not much axial or radial play and good teeth, you can build it as said.
The Cardone is usually a good company but the one I mentions is out of everywhere. Try NAPA. Anyway it seems that just a year later the motor got HEI's. So that is your direction. If you buy new, buy from a well known place near you and try to get a warranty.

I do buy imported repop distributors on occasion, when I'm making clones of the "Mini-HEI" that Langdon's sells. The basic unit is a distributor for an early 2.8 liter Chevy V6 with a centrifugal and vacuum advance. That requires modifying the housing and the shaft, and installing a different drive gear. The repop housing is made of a very poor quality aluminum alloy, and I don't trust the electronics. Part of the buildup is replacing them with American-made components.
Jerry

Great info guys, I appreciate all of it.

Bartamos: I was able to locate several of the Cardone 841692 dist on Ebay. Looks like they have to have an external coil, which I guess isn't a problem although I would prefer it all be together.

I agree, Coil-In-Cap better. 1978 Nova 250 uses coil-in-cap.

Check these out to verify.
1. AC Delco 88864760 (reman)
2. Cardone 841697
3. Cardone 301697 (reman)
4. Spectra GM24R
5. SKP SKDIGM24R
6. AutoLine Delco Remy type D2063 (Reman)

Some include cap and rotor, some do not.... so factor that into the price. Above info is from RockAuto website.

Bartamos,
I'm guessing that #1 or #6 is what would more than likely have been OEM, would you say that's correct? If so, I'd much rather go that route. I think I prefer #6 because it comes with the Cap and Rotor

What do you guys think about this route?

PerTronix 91162A Ignitor II Solid-State Ignition System, Delco 6 Cyl

https://www.speedwaymotors.com/PerTronix-91162A-Ignitor-II-Solid-State-Ignition-System-Delco-6-Cyl,300258.html

Carry an extra distributor set up with conventional points and condenser so you won't get stranded away from home when (not if) that Pertronix unit fails unexpectedly. ("Don't leave home without it!") Then be prepared to wait a long time for repair parts to arrive from the factory, as it's going to be impossible to find them at a local parts store. In the very unlikely event that a Delco module or pickup coil fails, the local store will have a replacement on the shelf. Remember- - -the whole reason HEI was developed in the first place was a government mandate that emission-related parts, including ignition components, had to last a minimum of 50K miles without being serviced or adjusted!
Jerry

"Carry an extra distributor set up with conventional points and condenser so you won't get stranded away from home when (not if) that Pertronix unit fails unexpectedly. ("Don't leave home without it!") "

That is what I used to do. I never needed it, but, I slept soundly.

Don’t forget to change the points in your glove box every few years. Keep them fresh .... just in case

I think the poster just wants to see us all fight each other about Pertronix again

Pertronix was invented to allow keeping the "look" of an original distributor and still have a pointless ignition. To maintain a more purist original presentation. It has a remote coil. You are not in that category with a 74 motor. Older motors don't really have an off the shelf drop in HEI dizzy. They are all aftermarket modified. So they use home made, Langdon or Pertronix. The price of Pertronix seems the same as a GM style HEI. So why are you asking? Why bother? You got your answer already.
Reviews on various vendor sites and forums still show problems with Pertronix. You will have no problems with a good GM dizzy.

Just my opinion but I would avoid the Pertronix. You never hear those mentioned without a warning to "carry a backup distributor" or "keep points, condenser, etc in your glove box." Failure rate is too high for me...especially for what those things cost. Good luck.

I carry a backup distributor (adjusted/tuned/tested) in all my old trucks (especially on trips), Pertronix or not.

I have found/experienced condensers as being less reliable than the Pertronix units.

You can fit a moped in the back of a truck, suburban or panel as a back up. But the price of those is more than a Langdon GM HEI. A Harley would have to have a trailer.....and they have an awful sound. What man doesn't like the smooth buzz of a moped and womens basketball?

Well guys, I see this did take the path that I seemed to find this afternoon in a couple of other threads, but I will assure that I didn't intend for it to go that way. This seems to be one of those questions that resemble whether or not you run stock steel wheels or rally's, whether you lower it a couple of inches or no. I understand that asking broad questions will invite broad answers both negative and positive.

I am really a novice at doing this so I just wanted the info. I figured with my new AAW wiring kit I'd just go ahead and go HEI since my motor isn't original anyway. I have a '25 Sedan that is original except that it sports a '28 motor and I just recently sold a '32 sedan that was a beautiful original car. I would prefer for the engine bay to at least look original even if it's not completely so.

That said, there have been a few terms thrown out here that I'm not absolutely sure about, was hoping you guys would enlighten this newbie a bit.

GM dizzy: I'm assuming this is an original distributor with points.

Langdon GM HEI: seems I found that Tom Langdon builds HEI's within the original distributor body - similar to the Pertronix but with better parts I'm guessing. (although he no longer does I6 - 250s any longer) Langdon GM HEI

What is 'FLAPS'

What is a 'GM style HEI'

Has anyone heard of this guy before? Dave Ray Small Body HEI


Thanks for the feedback

Some of us who hang out here have a tendency to speak in some pretty incomprehensible code. Here's a bit of translation:

"Dizzy"- - - -a distributor of any kind, electronic or mechanical point triggered.

FLAPS- - - -"Friendly Local Auto Parts Store"

"GM style HEI"- - - - -several clones of the General Motors type large diameter coil-in-cap distributor have been made by aftermarket companies with drive gears, housings, and oil pump drives made to fit Ford, Chrysler, and other non-GM engines. That's mute testimony to the effectiveness of the system they designed back in the mid-1970's. I've built a couple of Ford engines with similarly adapted GM distributors- - - -they're always good for double takes by people at car shows!

A quick look at the Dave Ray website looks like they're using original equipment point type distributor housings and converting them to some sort of electronic trigger system to eliminate the points and condenser. I haven't tried it yet, but I believe I could adapt an original Stovebolt distributor to run the GM pickup coil and reluctor instead of points, and mount the ignition module into an externally-mounted heat sink. That would do approximately what the Pertronix unit does, but it would use original equipment GM parts instead of the expensive and often unreliable proprietary parts supplied by Pertronix.
Jerry

.......and "HRL" - - - - - Expert knowledge. Fabricator. Racer. Instructor. Bike rider. Innovator. Old truck enthusiast. Community/Tennessee Volunteer. Funeral Escort. Patriot Guard Riders. Likable Hard Nut. Nam Veteran.

Thanks for the education HRL.......

Bartamos, thanks for adding the comments concerning HRL, he sounds like a good guy with a lot of experience and knowledge and willing to share it and be an all around help. HRL, Thanks for your service Sir and Welcome Home!!!

Thanks for the kind words! Maybe the next time my wife and I visit her sister on Dayton-Yellow Springs Road, I can pick up the tab for a coffee, or maybe an "adult beverage"! Welcome to Stovebolt, where the inmates are running the asylum!
Jerry

Hey guys, me again. So I went with a Cardone 84-1697, that's one of the ones GM ran in the '78 250's with the coil in the cap. My question, or verification is that the spark plug gap, should it be set at .035? I've seen where some say .045 and others as high as .060-.080 (but I think that may have been for v8s). What do you guys say?

6 cyl. and V-8’ spark plugs work the same.

Ed

I say .040~.045" and in a nutshell here's why: your HEI ignition is largely about higher spark voltage and more energy at the plugs or maybe I should say that was indubitably one of the main tenets of the whole design. The fuel we get today isn't what we got in 1978 and that should obviously be important to think about also. Some parts of the USA had unleaded fuel by then but not ethanol fuel. So, for one thing, ethanol blended gas runs leaner and this is another difference not contemplated in 1978. And ethanol laced gas will have water in it. We've discussed this point at length here already. One of the nice things about a slightly wider spark plug gap is this...whatever is in your carburetor has a much better chance of getting burned and especially if your fuel is leaner (which ethanol and water will conveniently accomplish for you). Another way of looking at this is a wider plug gap will add to or promote a more healthy ignition of whatever you are burning. And please trust me---the fire coming out of your new HEI distributor and HEI wires is plenty capable of hopping across a .045" gap. .035" isn't much different than what you'd be using with points, is it? Let's think a bit more about that---.035" is about the thickness of 2 sheets of copy paper wider than you'd have with a points distributor type plug gap of .030". So with a .035" gap, I'd say you haven't improved your situation much at all. I have a 235 and a Langdon's HEI and I use a .045" gap. Starts easier, runs better and burns more of the fuel (increased power). Isn't this what you wanted with an HEI in the first place? Good luck...

Thanks for that input Jon. Me and one of the more knowledgeable guys at FLAPS had thought that it should have been higher, he was quite amazed that it was the same. I knew I had read several places that guys had ran them higher, but I couldn't find it again. So thanks for the explanation, I'll pass that on to him too.

Hotrod Took a while to pick up on FLAPS...the dizzy makes sense if you watch a 216 running. Have alwats made my own HEI's out of almost any GM v-6 HEI most of these I didn't worry about the plug gap . Now all of these are on propane aalmost all are used L.P. equipment run fine. Have learned that if there hard to start the con verter is leaking thru making it rich,when there right they start with a little bump ! the best thing is never cold natured and fuel is 89 cents before taxes !

Jt roberts Have used V-6 HEI's in most of my 216,235,261,s I don't aim to get a lot of money in these,so use what they have in 'em if it will run. Some versions you reverse the gear,some take a stub shaft,get 1/2 inch machinery bushing shims at the farm store. One of mine just needed about 1/4 inch more on the oil pump drive I think it was a 292 version,so silver brazed on an extension,worked fine ! Basically just make it like the 216 distributor on the bottom.When you install be sure its not clamped down tight on the thrust where the gear rides right on the block.one other thing the big body will get kind of close to the plug side of the engine may have to move your wires and rotate it to clear. Also learned those big diamter HEI's get pretty thin when you turn them down. But they will work too !

jtroberts Almost any of the HEI distributors from v-6 Gm cars can be used in stovebolts, your 250 will accept certain inline HEI's as is I think. Mostly do older conversions.

Set the gap per manufacturers specification for the spark plug used on a 1975, and up, 250 motor with GM HEI. Which is .035. You don't need to fight every inch of the way on this. You don't have to guess or dream up another gap. It's .035, as you already know.
Don't mess with Mother Nature or Father Time. Move forward on this kind of minutiae.

Must use an even fire V-6 distributor, all terminals are evenly spaced around the housing. Odd fire will be hard to get to run on all cylinders.

Ed

jtroberts Can make your own HEI at home w/ simple tools