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I'm considering going to an internal coil on my HEI that is on a 250. What is involved in making that switch?

SixPac,

Can this be done...will the different caps swap between distributor bodies. The GM HEI with coil in cap takes only one wire from a 12v ignition source to power it...maybe you would use the wire that presently powers your external coil. This turned out to be more questions than answers...help will arrive soon.

Stuart

It can be done. It seems like the two are different animals and my best guess is that you'll have to yank the whole unit and install one that has the appropriate guts.

Inky05 has a tech tip for converting to an internal coil HEI model.

There's also a thread in this very forum in which clarifications are made.

Hopefully this is helpful and that someone who knows better than I comes along and sets me straight if I'm wrong.

Brendan,

I was thinking Sixpac already had an HEI with an external coil. He wants to dump the external coil and go to the newer integral unit...the "bigger" cap with the coil in it. I usually start typing before I fully understand the question...got to be the first ya know!

Stuart

atomarc,
You are correct. I do have a HEI with an external coil.

Sixpac,

Well at least we're on the same page. I have no clue if you can pull this swap off. I have the one piece unit and I know the plug goes into a receptacle in the cap. Knowing Detroit, the integral cap will be engineered NOT to fit on your distributor body.

I think you have two options. Wait for a reply from someone who has done this, or take the distributor out and drag it down to your FLAPS, and hope the kid behind the counter will spend some time and let you trail fit some caps.

I won't ask why you want to do this...maybe to clean up the engine compartment.

Stuart

It seems to me that the units with the external coils are smaller in diameter than the all-in-wonders. The cap with the coil in it wouldn't fit (too big).

Of course, I've never touched one with an external coil, so I can't say for certain. I'm just saying that if you get a cap, you might just want to go and get a whole dizzy from a boneyard.

I think that we're all on the same page. I'm just on a different paragraph. (not sure if I'm ahead or behind, though...)

I think they're identical. I have a couple of 250 distributors around, and they all look the same with the cap off.

It probably could be done but you would have to change everything. You would be better off getting a comeplete unit. Like Automark posted you just need to hook up one wire.

Why would you need to change everything? It's just the cap and coil.

My main concern is that the external coil is unsightly where I have it mounted (inner fender) and I'm not sure where to mount it if on the block. I also feel it is exposed to dirt and water. Not that I drive my truck that much, but I do worry about it.

I think they're may be some aftermarket dust covers and I'm looking into that.

I sometimes wonder if a Pertronix unit would be worth the money to have the factory look.

The original coil mounts on extended studs on the inner valve cover bolts. You could make them using threaded rod & nuts & washers. The factory did come with a snap on cover over the coil but it would be hard to find one. I f the coil is good you can turn the sraywash on the system & it will start right up.

Do you think the coil could be painted?

Sixpac,

No idea if this is a viable thought, but are you sure a stock coil wouldn't work with the HEI..they make some 40K jobs that, other than being chrome, look like a stocker, and could mount that way too.

Stuart

SixPac, I am at a loss as to what you really want, as you've spread this topic over three Stovebolt forum questions. I believe this is what the setup is supposed to look like.
[img]http://home.earthlink.net/~roadruner/coilimage.jpg[/img]
The cover that Wrenchbender mentioned is hard to find and often have the snap ears broken off as does mine. It fits snug enough that its been in place for a couple of years and I'm not loosing any sleep over it.
The wires coming out of the right side of the cover go to the dist module. The taped wires above those are the tach wire and the original cloth covered ballast resister wire. These go behind and into the left side of the cover. For all of those that want to start crying about the resister wire I can say this. It has fed this setup for two years and the previous coil-in-cap HEI setup for ten years and has performed just fine, thank you very much.
If you are still of a mind to change to coil-in-cap setup, you may or may not run into a phasing problem. I am using a coil-in-cap housing with an external coil cap and it seems to line up OK. The corner of the rotor tang lines up with the plug wire post in the cap at 6 degrees advance. As the timing advances, it moves into much better alignment.
This is what is at the heart of the problem.
[img]http://home.earthlink.net/~roadruner/Dist5.JPG[/img]
The upper dist is the one you have now with the cap index slot near the vacuum advance. I'm not sure how many degrees they are away from each other. I can tell you this. If you set your engine at TDC and pull the cap, you should find that the rotor and #1 are phased correctly. If you than put on a internal-coil cap, the rotor will be between cap posts. The dist gear has 13 teeth. If you move it one tooth, you will be moving it 27.6 degrees. The cap has six posts that are 60 degrees apart. I could be wrong, but I think with this match up the rotor would move to far off the back of the cap post at full advance. You could also try to cut a new slot in the housing. You would have to be careful there because the four attachment ears are 90 degrees apart. My best quess is that my setup is phased about 3degrees ahead and yours would be about 3 degrees behind. As I said, not a problem with mine.
I went into all of that because you said you could not find a 6 cyl HEI in the wrecking yards. Any GM V8 large body HEI coil will work. The short wire harness coil-to-module is the same on the V8 as long as it uses the same module. I assume you have the four pin module (two on each end). The plug for the source voltage and tach if you have one is the same for both coils with the idiot proof tangs so that they are plugged in correctly. You just have to buy a new 6cyl cap from the parts store.
Here is an idea. Keep the dist you have and move the coil because someday you may want to put AC on it and you would have to switch back. That is why I made the switch, even though I haven't gotten around to it yet.

Richard,

That is exactly what I needed! I see the distributor I have couldn't be converted, but see exactly where to mount mine. I could buy one of the ProComp ones for looks and mount it there.

Thanks for your help and the pics.