Inliners International Forums General Discussion Hi Performance GM HEI

I am trying to buy a GM HEI for my 250 CI motor. How do i know which ones will work and which ones wont? I know that it has a smaller shaft than most distributers but what is another way to know it will work for my motor? Thanks

It is stock stock inmy 78 PU. One out of mid 70s would not be computer interconnected.Any 70s inline6 aught to work.

Yeah my HEI came stock on my car, 1979.

Any distributor from a GM inline from 75-81 will work. They are always a couple for sale on ebay, but some have gone for big $$$

this one says its for an inline but it doesnt look like any HEI i have ever seen. anyone know why?

**** i forgot the link....here

http://cgi.ebay.com/ebaymotors/ws/eBayIS...ssPageName=WDVW

Once you've located an HEI for the six cylinder inline Chevy engine you can tell if it was for a computer or non computerised engine by whether or not it has a vacuum advance diaphragm. Non computer jobs have it and the computerised HEI does not. Instead it has a second short wiring harness coming out of the distrib hsg with 4 wires and a 4 pin plug.

Also keep in mind that the V6 HEI is not the same as the I6 HEI and won't fit.

When you find one you can use all the hi-po goodies for the 8 cyl HEI from MSD or whoever as that much is all the same whether V6, V8, or I6 as long as it is the coil-in-cap HEI. Rotors are all the same but of course the caps are for either a 6 or an 8.

A good place to begin with plug gap is .045" and use a good set of wires like Taylor Spiro Pro.

Freedom from points - ya gotta love it!!
Mike

I just checked that ebay link. That is the so called 2 piece HEI where the coil is a separate unit from the cap. It is a non computerised unit. Some guys prefer them over the all in one HEI with coil-in-cap. For street use I doubt you'd ever care one way or the other performance wise except in my opinion the all in one HEI is a cleaner looking package on a well dressed engine.

Didn't mean to double post separate responses. Just overlooked the ebay link in your original post.

I've got a friend who runs a 250 in a racing class. 375HP or so. He always uses the HEI with the seperate coil, something about more choice for coils. I'm not exactly a ignition expert so I couldn't really tell you.

they say you can put a regular coil on cap type on to this one. Is it true? Can you just change the cap to the standard all in one?

To tell if it is off a V-6 or inline, check the terminals around the cap. The inline ones are all equally spaced, Buick and any other odd-fire V-6's will be unequally spaced. Many sellers don't bother to point this out.

Ed Pruss
Longmont, CO

Im bidding on the HEI with seperate coil. Is it possible to convert this to standard HEI with coil on cap, by just buying a new coil and cap.

The separate coil and cap and coil in the cap are interchangable. I prefer the separate coil due to the ease and of changing and the variety of external coils and it removes alot of weight from the top of the distributor.

The easiest way to see if a coil-in-cap HEI is from a V6 or an Inline is to look at the distance between the shoulder where the clamp holds it into the engine or manifold and the underside of the main body. The Chevy 90 degree V6 unit is 1&3/4 inches ( exactly the same housing as the Chevy V8 HEI ) and the Inline unit is 4&3/4 inches. Another way is the V6 unit doesn't have a small shaft hanging out of the gear to drive the oil pump like the Inline does.

I have done several 200 / 229 V6 Chevy HEI's and Inline HEI's with the coil-in-cap and they all use the same cap. Stay away from any parts that fit a "Buick" or "odd fire" and you'll be ok, even Buick got away from them after about 18 months production - 1977 / 1978.

Does anyone have any MSD or Accel product #'s for the coil in HEI that isnt on the cap?

There is one thing to watch out for. The shaft diameter is roughly .489", top to bottom on most of the HEI's. I pulled one out of a 250 that had a lower end of .4666". The shoulder was just up inside the bottom of the gear and below the roll pin and I did not notice it. The bearing was nice and tight so I just dropped it into my engine. It wobbled around like crazy. The oil pump tang was sliding back and forth on the pump slot every half revolution.

I've seen people mount the external coil in weird places. The front bolt on the rear side cover and the rear bolt of the front side cover is suppose to have special bolts. These two bolts should have a stud on their head that the coil sits on and then a nut. That puts the coil just behind the dist.
I had the internal coil HEI, but have switched to the external to give me more clearance for a air compressor that I plan to mount above the dist.

Do you have a part number for MSD or Accel external coils? I need to buy one but i need to know which one is good.

Does anyone use the seperate coil HEI? If so what is the part number of the Accel or MSD coil you use? Thanks