I'm wanting to convert to HEI for my 68 442, it's a 400 with edlebrock 750 carb and performer intake and the rest is stock. Looking for any input, opinions, advice on swapping out the points distributor for HEI. What all do I need and what is the difference? Appreciate any input.

 

Why?

- Eric

 

Have you thought about a PerTronix conversion for the existing distributor? Because HEIs are from smog-era cars and can be difficult to adapt to earlier high-compression engines. Trust me, I know.

 

Some good options are. 1. Keep your points ignition just buy high quality vette points & cond and maybe up grade the coil, cap and rotor too to the higher quality stuff 2. Install the points eliminator kit from Pertronics. 3.Purchase a new HEI from one of the vendors who will set up to curve for the earlier non-smog era engines.

 

Was under the impression that HEI was a more reliable slightly better performing system? My distributer is fine but if there's a way to improve I'm all about it.

 

Not for a mild street engine.

You will get a bit more performance from an engine that revs highly, but for a regular engine, you are unlikely to notice any improvement from HEI, other than the acceleration increase that results from a lighter wallet.

Some people will say that their idle got smoother with HEI, but that may be because their points and condenser needed adjustment or replacement, or their distributor was worn.

Some prefer to never have to adjust or replace their points, which is fine if it's important to you, but with the mileage that most people put on their older cars, you'd only have to change the point every ten years or so, so for most it's really not a meaningful factor.

And what's more reliable - having to get out and possibly clean or readjust the points, or being stranded because an electronic module has failed? (It's happened to me).

- Eric

 

My experience was when I went from points to HEI waaaaaay back in mid eighty's I yanked a first gen dist from a 74 455 smoger. Young and stupid (old and stupid now) I stabbed it right in hooked 12 vdc to it and cranked her up. Well you can imagine how under impressed I was. So I pulled it and took it to a local carb/distrib guy who had a Sun curve machine and a pile of advance stops etc.... We refurbed that dist and set the vac and centfifugal adv to a more desirable setting to handle a low revving 11:1 comp engine.
Now I may have picked up a 10th at best confirmed by seat of the pants and repeated consistent time slips; but what I really noticed was how much smoother the acceleration was.
The same thing is achievable from a points dist as my original likely needed a tune up as well. But I liked the fact of not having to mess with points any more and the sparks a little hotter which allowed me to tune the plugs as well.

 

People who were not alive at the time don't know (or remember) that the HEI was conceived by GM for EMISSIONS reasons, not performance. The feds required that all new cars be able to comply with emissions limits after 50,000 miles with no maintenance whatsoever (that later got extended to 100,000 miles, which is why new cars have expensive platinum plugs). Obviously, points weren't going to meet that requirement, thus HEI. The higher voltage coil was used to both fire fouled plugs and to avoid misfires with the lean mixtures common in the mid-1970s.

The reality is that for a street-driven car, you will see no performance difference between HEI and a well-maintained points distributor. Claims of performance improvement come from people who have replaced a worn-out points distributor with burned points and corroded cap. Even a new points distributor would have provided a performance improvement under those conditions.

Personally, I've converted most of my cars to electronic distributors because I'm lazy, not because I expected a performance increase.

 

For those of you who have done it, did the HEI distributor screw up operation of the tick-tock tachometer?

 

Just connect the tach wire that previously went to the coil to the TACH terminal on the HEI. The HEI replicates the same tach signal as a points system.

 

Good to know. Thanks for the reply.

 

I am a big fan of Pertronix since you can put one in a forget it. I have had one in my boat for years and no problems. I probably don't get anymore horsepower but I think I do get quicker starting and longer plug life. However as Eric mentioned, no more that most of us drive our cars the longer plug life is a moot point. The Pertonix Ignitor II might give a little boost but I have not used one.

 

It's a very easy conversion to an HEI. All you need is a 12ga 12v switched source for power, connect your tach, and your done. Cap and stow the old resistance wire and bypass wire from your starter as they are no longer needed.

Note, the stock timing settings no longer apply as the timing curve is different. You may need to limit your vacuum advance.

 

And if you do need to limit the vacuum advance (which is likely) get the advance canister that is an adjustable "travel limit" and not an adjustable "rate" can. There is a difference.
A good starting point for a super tune is 12*BTDC base timing. 10-12* on the vac advance can at idle on full manifold vacuum, not ported. Then bring in the centrifugal for a total of 10-12* all in at 27-3000RPMs This equals 36 total degrees BTDC at ~3K rpms. Play around from there. Olds in street form like 34-38* BTDC of timing...generally. This is where I have mine dialed in. I have a 11:1 400G engine with a W30 grind cam. It runs like a raped ape with zero spark knock. Be real sure you have zero vacuum leaks and have the air/fuel adjusted properly using plug read and vacuum gauge methods. You should be able to really dial in the E brock AVS carb if you follow their tech instructions and play around with the springs, rods n jets. Contact them if you dont have the sheet with the fuel plot curves.

 

http://www.pertronix.com/prod/ig/ignitor/default.aspx

 

IF you decide to change to an HEI (with associated hardware):
Recalibrate the curve.
Change the regulator to a solid state one.
ALWAYS carry a spare module.

 

"It's a very easy conversion to an HEI. All you need is a 12ga 12v switched source for power, connect your tach, and your done.... the stock timing settings no longer apply as the timing curve is different. You may need to limit your vacuum advance. "

In my experience, you are a long ways from "done" after you kook up the wires. You have to learn how to read Mech. Adv. [unless you have a dist'r machine handy]... and adjust to suit. You have to learn how to measure Vac. Adv. degrees, and adjust to suit. Adjust those then the initial timing. Convert to manifold tap VA and see if it likes that better.... quite a bit of fiddling if you have not done the math before and whatnot to ascertain what amount of advance your mechanical is providing. PS this should be ascertained by holding the weights outward, NOT my moving the rotating plate which is moved by the weights, because if you move the plate with your fingers and not with the weights, it will move MUCH farther than it will in real life, with only the weights driving it. A lot of details.

Surely there is a youtube instructional....

I had the process all written up with pix at ROP before a Great Crash lost it all.

 

I think you made a slight typo above. Those numbers don't add up to the 36º total advance (initial + mechanical) the engine needs. The vacuum should be added after the total advance (initial + mechanical) is achieved. So, for the above there should be ~10º initial, ~24º mechanical, and then ~10º vacuum advance.

 

This is true, you want a total of initial + mechanical to be around 34-38, then add your vacuum of 10-12 to be around 46-50. Give the engine what it wants.

 

Some excellent responses here, I learned a little sounds like I got more to learn as I don't have a clue what some of y'all are talking bout lol! Also sounds like either/or will do, I think I'll probably go with the pertronix set up just for piece of mind, not that there is anything wrong with the original distributor but it does have close to 100k on it. I appreciate all the input. I'll have to do some homework cause Im a bit ignorant when it comes to the timing and vac advance stuff.

 

I have found that the problem with points is that the new condensers are junk, to the point that I carry a spare. The condenser is mounted at the coil for easy access.

 

This is true. In fact, the old ones seldom go bad (though occasionally they do), so sometimes you're better off keeping the old one in place, rather than replacing it with a new one.

And, yes, you can install the actual, working condenser anywhere, so if you want, you can install it between the (-) coil terminal and ground, with a second one attached to ground right next to it, but not connected to the (-) terminal, making it very easy to get to and change.

- Eric