HEI with vacuum adv. & a 4-pin plug?

[71Blazer]

I posted this on the engine/drivetrain board but I thought I'd try fishing here too...

Can the 4-pin plug on HEI be bypassed or not used at all?

I'm considering an HEI that has vacuum advance and also the 4-pin esc plug.

I need the vacuum controlled advance since there is no computer in my '71. Can I just hook up the vacuum canister and forget the 4-pin plug?

I did a search to see if the 4-pin plug could be bypassed or not used at all but I couldn't find a definite answer?

Thanks!

[redz 1970 K5]

Good question! I never thought about it. Any reason not to just use an older distributor without ECM control and with vacuum advance?

Must be a good deal! Of course, I have seen a ton of good older non controlled HEI distributors on Ebay for cheap.

[71Blazer]

It's for sale from a fellow board member and I think "$60 shipped" is a fair price with "an msd hot coil as well as a hardened drive gear...has accel cap and rotor as well."

I trust people here more than I do on ebay whether that's wise or not...?

[67ChevyRedneck]

I don't know either....I used an older HEI. Just plug it into the cap, give it a power wire, add the tach wire ,plug the vacuum into the carb....done!!

[beaterC10]

You might be able to use the dizzy if you add the correct jumpers on the extra plug. This dizzy uses a knock sensor and ECM to control the spark advance. You might look at the FAQ or search the 73-87 board, guys there defeat the spark control system on a regular basis by jumpering the wiring or simply replacing the dizzy to a non-ECM controlled version.

Prolly not cost effective to convert this dizzy to the older style. You have to change the module, harness, and I believe the pickup coil.

[arkracing]

If I had a closer picture of the 4-pin connector...i could tell you which two wires to jump.

1st and 3rd...Black/Purple and then skip one to Green (but don't hold me to it) splice these two wires together

I wouldn't pay $60 for it though...go the junkyard and get an older one...

if you had it lying on the shelf then yeh i would use one..I had one in my V-8 Ranger...converted to Chevy V-8 of course..and it ran for two years before the module went..then i just put a regular one without the 4-pin in.

I wouldn't pay for it (especially not $60, $10 maybe - haha)..but if i had it..i would use it (confused yet) if you go to swap meets regularly you can find them without the 4-pin for about $25 - might not be the first one you see but if you look around offer $20 and you might be surprised...i've bought a few for $20 @ swapmeets - boneyard might be a little more

[Tx Firefighter]

Jumper "A" to "C" and it will run fine. We did that a lot at the dealership when the ESC computers would fail on those trucks.

It will have a 7 pin module. If that module ever fails, you can replace it with a normal 4 pin module and rob the inner wiring off of a normal HEI and it will now effectively be a normal old HEI.

[71Blazer]

Thanks for the help!

[Dick Dale]

While on the topic of HEI, I am getting ready to order one from Summit or Jegs and need to know what to order. I bought a GM longblock (290hp, 326ft/'lbs) and it needs an HEI. I have no idea how to hook it to the trucks wiring and need advice. Can I use one coil wire for the new electric choke and one for the HEI or do I need an unfused source?" I am not looking to spend a ton of money and was looking at the Jegs or Summit brand.

[71Blazer]

This link was sent in response to my question and should help you figure out your wiring.
http://www.73-87.com/7387garage/drivetrain/escrepl.htm