Wow. Its amazing. The car runs so much better. Much better acceleration and idle. Holy crap. It took all of 45 minutes and $80 at a junkyard and this is with out a doubt the best upgrade I've ever done for it. Good gosh. I have to go get some new sparkplugs now (bought the wrong kind), but I can't wait to see what the difference will be with new plugs. I need the resistor kind now, I guess.

Also, any recommendations on gapping them? I read in Chilton's about how most years were at .0045 (or was it .045?) but that a couple of years had .00(0)60! I think common wisdom would say go with the 45, but what is up with the 60? Is there any benefit to such gapping?

Thanks to all who recommended HEI. It made an enormous difference.

Glad your improvement is so obvious. I felt the same way. It's really hard to beat HEI, even a stock HEI (with any set of points, that is). It's reliable, cheap, and low maintenance.

Regarding the spark plug gap, I'm running .060 on mine without any problems or misfires etc all the way up to 6K RPMs, but that could be because I upgraded the "stock" coil to a 55,000 volt Accel version.

Someone else on the forum can verify the technical reason(s) for the spec'd. gap differences, but in general, I believe the larger and more intense the spark, the better the combustion and resulting power. So, ideally, the larger the gap the better (as long as you have enough voltage in the coil at high RPMs [translates to shorter recharging time] in the coil to drive the spark across the larger opening). That's why the racers often use magnetos (because the voltage and amperage both increase with RPM).

Hope it helps.

Enjoy your new-found thrill. :-D

Mike

I have mine gapped at 35 thousanths, 350 with HEI.

Brian

8) Hey Guys! From what I was told by a retired GM mechanic when they changed over to the hei system the engineers thought with so much more sprak it might burn the plugs up so they opened the gap to .060 . Later on you notice they closed the gap to .045. I personally gap mine at .035.

PaPa John

The main purpose of the larger gaps they used to use with hei was to prevent lean misfires. If you look at those applications that used the wider gaps you'll see that they were low rpm applications. Once efi came into common use, super-lean mixtures weren't needed to meet emissions.

The reasons why racers use magnetos is they are self-sufficient (meaning they don't require a battery). As a former spint car owner we ran a magneto because you don't use a starter or tranny so you can ditch the battery and the weight. Thats part of how we could make 600hp car that only weighs 1250lbs. As far as plugs go you don't buy resistor plugs you buy resistor wires. As for the HEI make sure you put a ground strap under the coil new caps dont always come with one.

The performance trend now is to smaller sparkplug gaps but I use .045" and I think it is a good compromise.

I ended up gapping them at .045. Car runs like a dream. Highway cruising is amazing. Its good and responsive at higher RPMs, but with this high gearing in the rear end, it isn't going to take off too quick. But, since its our daily driver, I can live with it. Great upgrade.

Just got back from a couple of hundred mile round trip. Wanted to give you all an update.

With points: 13 mpg
With HEI: 18.0 mpg!!!

This was from San Diego to up into LA at 70-80mph.

This is as good as I could hope for. Well, till the rebuild happens.

Let's see.......

COST:
45 Min to install (approx $40 value)
$80 purchace price for the HEI
$25 for a new set of premium plugs

$145 total spent.

BENEFIT:
35% improvement in fuel mileage (not to mention the increased fun factor), estimated savings at the pump approx $250-$300 per year, (more if it's a daily driver) means that upgrade pays for itself in about 1/2 a year of driving or less.

Now them's cost/benefit numbers we all want to see!!!!

Congratulations!!!!!! (Bicycles aren't much better than that)

My '72 still has standard ignition and when it sits for a few days it's hard to keep running at first start-up. Would HEI make a difference? And if I want to pull one from a salvage yard, will any small block Chevy do? I assume that I need the coil too. Anything else I need to know?

8) Depending on what your local salvage yard wants for a used HEI distributor, Jegs or summit have new HEI's including coil, cap, rotor and adjustable vacuum advance for under 100.00.

Not familiar with Jegs or Summit. Got URLs for them? Oh, and thanks for being so helpful!

8) www.summitracing.com www.jegs.com

My '72 still has standard ignition and when it sits for a few days it's hard to keep running at first start-up. Would HEI make a difference? And if I want to pull one from a salvage yard, will any small block Chevy do? I assume that I need the coil too. Anything else I need to know?

Well, mine was a '65 and it had very similar problems. HEI made all the difference in the world regarding starting.

Pretty much all SBC engines will work.

When I got mine, it was $75 and it included rotor, coil, and all. It took all of 45 to install and adjust. Best investment I've ever made.

Is there much performance difference over a stock type unit and a low end performance one from accel or mallory?

I just got one from Jegs with a new set of matching wires. It is not in yet, but will be soon. The whole thing was under 140 bucks with shipping. In my opinion, I would rather spend a few more bucks (the dist. was $ 98, i think) and not take a chance of getting a bad part. I do use a lot of stuff from the bone yards, just not elecrical stuff that I cant tell if it's any good. I will update y'all when it's in!