'74 hei

[flyboyjack]

Well, as I mull over, (still), the switching from points to an HEI, ..I discovered that GM first used an HEI in the '74 SBC. I'm wondering if anyone out there has installed one of these in their '71 or '72 C10 SBC. (I'm still running all OEM). If you did, was this just a plug 'n play with the exception of getting a switched 12vdc power supply which I have procured from the guys at YearOne, (and it's PINK!). Or do I still need to "tweak" the weights and springs, etc.? I also think this may look the most "stock" with the exception of going the Pertronix route, which I'm sorta leaning away from.

Thanks for any advice.

Jack

[StingRay]

Should drop right in with the elimination of the resistance lead and an upgrade to the heavier wire. You may want to change the gap on your plugs to the same spec as the 74 used. On a used unit beware of the pick up coil wire getting fatigued and breaking or being ready to. Just replace it. Can do the bushings at the same time and replenish the grease well for the top bushing. Also only use AC Delco modules. The other crap just lets you down. Changing mechanical and vacuum advance could be a good idea depending on what your truck will tolerate.

[kwmech]

Been putting them in for over 30 years. Replace the resistor wire at the bulk head fitting with the pink wire and eliminate the yellow wire from the starter up. Unless you are hot rodding this thing, the factory springs should work just fine. Open up the spark plug gaps to at least 40 thou.. 45 is sometimes better

[flyboyjack]

Man,... that was quick and EXACTLY what I wanted to hear. Thank you. Rock Auto,...here I come!!

[HO455]

Just to address your question on the weights and springs. The advance curve of your average early 70's distributor is going to be conservative and biased towards meeting emissions (Unless you happen to find a high performance version). All this means is that there are horsepower gains to be made if you want to have your distributor curved. This also means you should not have issues with detonation caused by too much advance too soon.
Short answer is you don't need to be concerned that the weights and springs need changed. Just be sure they operate freely and with a smooth return zero advance.

[Mike C]

You should use the search button. You would probably find a 100 threads on doing HEI swap.

I would get a complete one of Amazon or eBay. They run about $50. Then replace parts as needed with name brand stuff. But I've had great luck with the cheap HEI's.

[flyboyjack]

Thanks all for the info. I know it was lazy, but I wanted specific inputs on using a '74 GM HEI. So I didn't "search" Thanks to y'all, I've got great advice/info.


Jack

[kwmech]

Nothing special about it being a 74. Actually I thought the HEI started in 75 myself. Any V8 hei will work until they went to a 7 pin module

[Mike C]

Originally Posted by kwmech

Nothing special about it being a 74. Actually I thought the HEI started in 75 myself. Any V8 hei will work until they went to a 7 pin module

Cadillac had the HEI in ‘74 and maybe the L82 Corvette, but they went across all GM lines in ‘75.

[LEEVON]

Something you're NOT going to find in searches, to help answer your question. Aftermarket distributors are typically questionable quality. And they are pretty much NEVER curved correctly, often they limit total advance and even with bushings, springs, etc you may have a hard timing getting to 34-36 degrees total. You should do some troubleshooting to make sure that you're getting all of the timing your engine needs and when it needs it. Also if you can put an adjustable vacuum canister on it that will help with setting your idle/light throttle advance for a cleaner more efficient engine. Start with a quality distributor.

[flyboyjack]

Originally Posted by LEEVON

Something you're NOT going to find in searches, to help answer your question. Aftermarket distributors are typically questionable quality. And they are pretty much NEVER curved correctly, often they limit total advance and even with bushings, springs, etc you may have a hard timing getting to 34-36 degrees total. You should do some troubleshooting to make sure that you're getting all of the timing your engine needs and when it needs it. Also if you can put an adjustable vacuum canister on it that will help with setting your idle/light throttle advance for a cleaner more efficient engine. Start with a quality distributor.

Thank you very much. RockAuto has reman HEI's for '74 SBC motors. My hope/guess is that if these are true GM components, they should work as you describe.

Jack

[68 P.O.S.]

Read this thread below on setting up your HEI...specifically the posts from former member HEI451. He is the HEI master and posted a lot of good info in this thread to get your HEI setup the correct way. It's amazing how a properly functioning HEI will make your engine run.

http://67-72chevytrucks.com/vboard/s...d.php?t=550048

[68 P.O.S.]

The highlights are:

Find #41 weights and #375 centerplate from a junkyard dizzy and install them (normally found in trucks and Suburbans).

Buy the Crane 99600-1 adjustable vacuum advance kit and install 1 blue spring and 1 silver spring (ensures full mechanical advance all in by around 2800 rpm).

Install Crane vacuum canister and set it up as outlined by HEI451.

Hook it up to manifold vacuum, advance total timing to 36 degrees btdc, reset idle to 750 rpm, and enjoy the new engine responsiveness.

[kwmech]

Originally Posted by 68 P.O.S.

The highlights are:

Find #41 weights and #375 centerplate from a junkyard dizzy and install them (normally found in trucks and Suburbans).

Buy the Crane 99600-1 adjustable vacuum advance kit and install 1 blue spring and 1 silver spring (ensures full mechanical advance all in by around 2800 rpm).

Install Crane vacuum canister and set it up as outlined by HEI451.

Hook it up to manifold vacuum, advance total timing to 36 degrees btdc, reset idle to 750 rpm, and enjoy the new engine responsiveness.

Good info there

[hayhauler71]

https://www.proformparts.com/product...gear-black-cap

Here is a link to a drop in distributor .

[68 P.O.S.]

Proform is good, very reliable stuff. Pro-Comp is the company to watch out for...they're on par with the Skip White stuff and their cheap Chinese electronics and shafts. With the Proform, you'll likely have to change the springs still and you'll have to dial in the vacuum advance. It may already have the correct weights and center-plate as most aftermarket companies have moved towards those. You'll have to see the spec sheet on it for that and the vac advance to see how much advance they give you. Also, as someone already mentioned, the standard spark plug gap for the HEI is .045.

The right way to do it, and probably the best move for you, is to talk to this guy https://www.davessmallbodyheis.com/. You can send him whatever dizzy you decide on & your engine specs, and he will throw it on his distributor machine and set it up perfectly for your truck.

[flyboyjack]

Originally Posted by 68 P.O.S.

Proform is good, very reliable stuff. Pro-Comp is the company to watch out for...they're on par with the Skip White stuff and they're cheap Chinese electronics and shafts. With the Proform, you'll likely have to change the springs still and you'll have to dial in the vacuum advance. It may already have the correct weights and center-plate as most aftermarket companies have moved towards those. You'll have to see the spec sheet on it for that and the vac advance to see how much advance they give you. Also, as someone already mentioned, the standard spark plug gap for the HEI is .045.

The right way to do it, and probably the best move for you is to talk to this guy https://www.davessmallbodyheis.com/. You can send him whatever dizzy you decide on & your engine specs, and he will throw it on his distributor machine and set it up perfectly for your truck.

Wow, this is seriously better 'n Christmas. I am taking all this info and keeping it in a safe place for reference. Thanks so much. These old 350's are such smooth motors anyhow,...I can't wait to do this!

Jack

[Mike C]

Even the GM HEI is known for issues for getting enough and the right advance curve. They were maximized for low compression emissions motors. Vacuum advance was a big part of the equation and there were many different vac cans that changed all sorts of things in the curve and many have been discontinued. The aftermarket adjustable ones just don't do the same things as the GM ones.

Don't think you will get a 1974 HEI when you buy a reman from RockAuto. They will be very few Hollander Interchange numbers that cover a BIG spread of vehicles.

It's hard to argue with a $49 distributor even if you do have to replace parts in a couple of years.

But if you want a better HEI, the MSD Streetfire for around $160 is the way I would go. And I own a couple for my higher performance engines. But for upgrading from points. Spend $50 and get a RockAuto coil and module to keep in the glove box.