derf

Ok, I can't seem to find much with the search so if this is covered anywhere, I apologize.


I'm going to be adapting a GM TBI system to the AMC 401 in my '77 Jeep. I'll be using a Holley adapter on a 4bbl manifold and a throttle body from a 454. I've got a complete wiring harness from a wrecked '89 Suburban and a schematic and I know how to adapt what I'm getting to what I have as far as the electrical. I also have a 7747 computer for the TBI conversion I'm doing on another engine. But since I'm doing this 401 first, I'm probably going to use this computer on this engine and get another 7747 for the other engine.

What I don't know much about is the HEI ignition. There are at least 4 manufacturers which machine a custom billet base to use a GM style HEI cap and rotor in an AMC engine. But they're all "one wire" non-computer controlled HEI systems.

What I'd like to do is get one of these distributors and adapt it to work just like an HEI distributor does in the stock configuration. Trouble is, I don't know exactly what I need. Can someone educate me on how the HEI is set up for a stock TBI installation?

What kind of advance does the HEI use? Vacuum? Mechanical? Computer control? Some combination of the three? What about setting timing? Is it done just like any other distributor? And what's the initial setting? What do I have to do to convert a "one wire" HEI to work with the TBI? Are stock parts adequate or are there aftermarket parts which are better?

Any help y'all can offer is most welcome.

ihscout

http://www.justih.org/Binder-Bench/s...ead.php?t=1182
should find everything here.

derf

Thanks for the help. Trouble is, his main article link is broken. I get a file not found error.

Bill usn-1

Try the FI forum at www.binderbulletin.org

I'm still repairing the links on the JustIH board!!!

jeeps2creep

Hey Derf, what do you want to use? The Hei's are pretty versatile so its all in what you want. If you want just the one wire hook up ....just install the vacuum advance type. Now if you want to have the ecm control the timing then just get a internal Ignition Control Module assy. from the junk yard and install it. ( have to drill and tape like one hole)You can also just keep your 401 distributor and get an external ICM and wire it in.The Hei is the best thing since sliced bread...if you ask me.

The advance thing is another story though...been looking at that for a few weeks now with no luck on good info(as far as what if any diff's are ) because its not a stock application like most have. What I have seen though is the same characteristics on both the vacuum adv. and ICM advance.

If you want you can email me or PM me and I'll try to help you out with what I have / got / know. BTW , where are you looking at for the 401 HEI? I was looking for a donor for my 360(have a ford base for 258) but not sure what to get or what it comes out of. I really dont want to spend $350-400 for what the junkyards got for 10.00.

derf

I'm looking at getting a full blown computer controlled HEI system to go into that 401 so it works just like a stock distributor in a Chevy motor.

Upgrading my existing ignition is not a good choice. AMC still used the Pertronics ignition in 1977 and that's what I've got. They switched to Duraspark in 1978. I could probably scavange a Duraspark system and work it in with a TFI upgrade but I don't want a patchwork system like that. If anything, I can use the MSD distributor from my CJ7 project and buy something else for it when I get back to it. (Edelbrock's EFI manifold comes with a distributor...)

I'm thinking about getting a Mallory 85 series HEI distributor (8560001C) that runs about $170 at Summit. It's an HEI top with an AMC base. But it's a non computer controlled distributor with the 4 pin module. However, I can probably grab an HEI distributor when I find the throttle body at the savlage yard and swap the 7 pin module along with the wiring harness into the new distributor.

What I really need to know now is whether or not the TBI based HEI uses any vacuum or mechanical advance. If not, I can just not hook up a vacuum hose to the distributor and lock down the mechanical advance.

jeeps2creep

OK, you want a external then, so what you need is a newer ( 80's ) distributor. Just make sure it has the stator / pickup in it and use a 7 pin external Ignition Control Module and then wire it in or better yet just get the wiring and connectors from the junk yard. There are one or two other items you need , cant remember right off the top of my head but can get for you or let you know what they are.

78C10

The HEI distributors in all EFI applications that I'm aware of, including TBI, are completely computer controlled advance. Sounds like you know what to do next.

Actually, Performance Distributors (I'm sure there are others, too) has a "Vacuum Advance Eliminator". As long as it's a GM-style vac advance unit, this would take it's place. They get $9 for it. Part# 333333. This way, it doesn't look like you forgot something.

ben73

I just converted a Ford 302W to run GM TBI. I modified the shaft of the GM small cap dissy to fit the ford block. It works well and looks tidy.
Alternatively, if there is a magnetic triggered electronic dissy available for you motor, all you have to do is lock the advance and connect the pickup to a chevy module.

derf

Well, I know for a fact that my MSD distributor can lock out both vacuum and mechanical advance (it's already set up that way for my CJ project that's on hold). I'll just get the 8 pin module and mount it out of the way.

A lot of good info on where to get the parts and wire them here: http://www.megasquirt.info/ms2/GM_7pinHEI.htm

Thanks for the help everyone.