Six cylinder distributor: Points vs HEI

[68gmsee]

Lately I've been reading where a lot of you strongly recommend HEI distributors on these old trucks so I'm starting a one month test on my 68 GMC six cylinder 250 with single barrel carb.

Now, I'm very familiar with HEI's since my 69 with 350 has one on it and of course most of the vehicles I've owned in the last 30 have had them. But, I had read some 15 plus years ago in some old cars magazine that there wasn't much to gain on a stock six banger with single barrel by converting it, so I decided to test it myself. I went to a local salvage yard and picked up an HEI with the integrated coil and vacuum advance on it.

Here's my plan: Since I don't have anyway to measure horesepower I will monitor the gas mileage and daily operation and report back.

If I notice a tremendous change in operation and gas mileage right away I will let you know.

[Longhorn Man]

also pay attention for easier starting, better idle, better throttle response, better low end torque as seen by needing less throttle to take off from a stand still and less down shifting... also not how often you won't have to mess with the points.

The magizines were most likely talking about power wise, and since they pretty much always crapped on the inlines, they said it wasn't worth it.
heck, in 75, all the mags were telling you how to get rid of the 'newfangled' HEI 'junk' and swap over to a 'tried and true' points ignition system.
That would be like an article on putting a carb on a Z06 vette today.

[68gmsee]

I hear you on the points thing. I'm hoping to see some difference in mpg. I was getting 16-1/2 to 17 with the points on the highway so we'll see if it gets improves some.

[PanelDeland]

I seriously doubt you will go back.I have to say that of all the mods to my truck, theHEI made the most difference in driveability.Rebuilding the front end helped a lot,lowering helped some,new brakes were good,but just for being able to drive,lug the ole six down some and acceleration the HEI wins.

[newbraunie]

I am doing HEI conversion om my 292 6 cyl today. Looking forward to all the improvments I have heard about!

[68gmsee]

Update... So far Disappointed. But then again, this is a 250 six cylinder with 1 barrel rochester.

I installed the hei on my 68. I took it off a 6 cylinder van and it looked pretty decent. Had no noticeable wear.

I replaced the cap and rotor, replaced the spark plugs, and the wires then regapped to .045.

On this 250 which has real low mileage (30K now) I did not notice any difference in the power area. But I also don't do much speeding. I just mainly toodle around town with an occasional run to an out ot town property that's 25 miles out.

Gas mileage actually went down to 14.5 mpg from around 15.5 and I found out I had a miss at around 65 mph. I think this was because I had a vacuum leak on the carb base gasket.

I've swapped back to the points distributor and will run it for a couple of weeks the same way I did the HEI and repost my findings.

[Elephanthead]

A properly maintained point distributor works fine, HEI though is set it and forget it, unless you rust the rotor or crack the cap, heh. I personally have never touched a distributor unless one of my junkers refuses to start.

[Stock72c10]

I will be watching this thread closely as I am replacing the carb on my 6 soon (as soon as it arrives) and my next step will probably be HEI once I get everything with the carb straightened out.

[bean]

i've tried this swap twice and really didn't see much in the way of performance difference on either occassion. To me, it's just more a matter of convenience in not having to fool with points. this last time I tried one of those petronix kits on the 250 in my 69. in my opinion that performs just as well as the hei swap and is about the same price.

[Brad]

68gmsee, did you advance the dist. to around 10-12* ? The old points like around 4-6*, but you can increase that for HEI. By doing so I think it burns the fuel better, giving better mileage.
So it's unclear in your last post as to what you attribute the drop in mpg's. Do you think it's the HEI as opposed to your vacuum leak?

[Old Bluey]

I did the Pertronix Ignitor conversion on the stock distributor a couple months back. I've got a stock 250 with the single barrell carb as well.

The results made me really happy on the ride home. Super quick starts and noticeable lack of throttle use is a huge bonus. And the install makes any monkey (like me) feel like an electrician. Best upgrade under $100 I've made.

[68gmsee]

Originally Posted by Brad

68gmsee, did you advance the dist. to around 10-12* ? The old points like around 4-6*, but you can increase that for HEI. By doing so I think it burns the fuel better, giving better mileage.
So it's unclear in your last post as to what you attribute the drop in mpg's. Do you think it's the HEI as opposed to your vacuum leak?

10-12 degrees sounds like a lot, but no, I didn't advance it that much. I advance it slightly to 6 degrees btdc.

Re: the mpg. I'm not sure about that one. I swapped the points dis. back before I realized I had a vacuum leak in the carb. Not sure if that was the cause.

I'm going to run it for a week or so with the points dis. and then going back to the HEI for another trial run.

[Brad]

Originally Posted by 68gmsee

10-12 degrees sounds like a lot, but no, I didn't advance it that much. I advance it slightly to 6 degrees btdc.

Re: the mpg. I'm not sure about that one. I swapped the points dis. back before I realized I had a vacuum leak in the carb. Not sure if that was the cause.

I'm going to run it for a week or so with the points dis. and then going back to the HEI for another trial run.

I think there are a couple problems here. First you had the vacuum leak- that'll cause poor mileage right there. Sounds like you fixed it. Second, you need to advance your dist. to the point of where it starts pinging under heavy acceleration, then back it off slightly. That's usually around 10-12* on an HEI. If that's not where your V8 one is, you might want to check that as well.
Man, you're making this HEI thing way more difficult than it should be by putting it in and taking it out, then putting it in again!

[john]

Theres no way a hotter spark can hurt the driveability.

[Spray-Bomb]

Dad & I put one in his old 250 & it made it a LOT better

It will idle, accelerate, & cruise better than with the points

[68gmsee]

Originally Posted by Brad

Man, you're making this HEI thing way more difficult than it should be by putting it in and taking it out, then putting it in again!

Actually, it's no problem. I have the old set of spark plugs (still in good shape) gapped to .035 and I have two marks on the block one for the points dis and one for the hei. I just put the #1 piston on tdc compression and pull out one distributor and install the other. About 30 minutes total.

As I mentioned, this is an almost stock 250 with single barrel. Not sure if that's the reason I don't notice a performance difference but, I'm going to run it with the points dis for a while and then go back to HEI. I'm mainly interested in the gas mileage gain or loss at this time.

[beautimus]

just chiming in to wish you luck on your hei swap,
and to tell you of my experience with this.
i swapped to an hei and yes my milage dropped slightly, but that was due to my lack of experience in this conversion.
after regaping the plugs, and adjusting the timing with a light.
i actually picked up a couple of points on the mpg. but the throttle was crisper, and the truck gained some pep.
i still wasn't getting the results on cold starts that i wanted,
until i came across an old monojet with an electric choke. i rebuilt the carb, and took a while to get the choke set right, but what a difference, that made. to be honest, i hate the stock divorced choke stuff, almost as much as i hate points.
this is the utimate "set it and forget it" combo in my humble opinion. again best of luck to you.

[68gmsee]

Thanks for all the suggestions...

I want to run it for at least a full tank of gas, maybe two, before going back to the HEI. Then, I will try the different adjustments as suggested to see if I can see a difference and report back.

[68gmsee]

250 six cylinder HEI upgrade update.... I just got finished rebuilding the HEI Distributor and going to try it again.

I dismantled the HEI dis to see if there were any bad wires, etc. and I found the internal wires to be old and the connectors had a build up on them. I also saw that the windings on the pickup coil looked bad.

I removed the drive gear and replaced the pickup coil, capacitor and regreased the housing and shaft (The rotor and cap I had replaced already).

I polished and cleaned all the connections including the ground strap and put new heat sink grease on the module. Seems to be running real good and I do believe I can tell that there's a difference in the way it's running.

I have the plugs gapped at .045 and the timing advanced to 8 degrees (might play with that one some). It's got a full tank and I'm going to see how it does with the mileage thing...

[RANDY COX]

Do it,doo it,dooo it.i swapped and like the results.

[redhead69]

I did one on my nova.. 250 monojet and the improvements are noticable to say the least. Im with others, one of the best things Ive done to older vehicles.

What wires did you put on it? There is a difference between the hei wires and the traditional breaker wires. Get wires off say a 78 truck with a six in it (anything with an hei)

[68gmsee]

Originally Posted by redhead69

I did one on my nova.. 250 monojet and the improvements are noticable to say the least. Im with others, one of the best things Ive done to older vehicles.

What wires did you put on it? There is a difference between the hei wires and the traditional breaker wires. Get wires off say a 78 truck with a six in it (anything with an hei)

Probably should have taken the wire from the vehicle when I got the HEI, but for now, I'm using a 12 gauge wire from a boat trim motor. It has the same type of connector at the end as the resistor wire had.

[68gmsee]

Forgot to mention:

If anyone is interested here is a good site for a quick reference when converting. Has a good drawing and even lists part numbers if any requires them.

http://rmcavoy.freeshell.org/HEI.html

[redhead69]

Originally Posted by 68gmsee

Probably should have taken the wire from the vehicle when I got the HEI, but for now, I'm using a 12 gauge wire from a boat trim motor. It has the same type of connector at the end as the resistor wire had.

naw man plug wires

[68gmsee]

Originally Posted by redhead69

naw man plug wires

Oh...

I got some new ones at the auto parts store for HEI.