HEI on a 70 350 sbo-do i need it?

[bill]

Hey guys,
Just wondering if I need to use a non-computer HEI or a computer HEI or a standard Distributor when I swap the 3.8L for the 350sbo? Will the computer work with the 8cyl or will I have to find a 307 prom to put into it?

Thanks!
Bill

 

[peteyb]

Go with the non-computer controlled version. Then it's a single wire hookup. Plain and simple - can't get much easier. Just make sure you also adjust your spark plugs for the increased juice.

 

[bill]

Thats what I was thinking too. But, where does the computer wire(s) hook up on the stock distributor>? I dont see anything different with the non computer part from the computer one.

 

[peteyb]

The computer controls the spark advance and the wires that hang off the distributor make their way back into the ECM. You can simply use the stock computer-controlled distributor that is/was in your 307, but you will lose the advantage of the spark advance/retard.

 

[megaladon6]

since you're going to a "stock" engine you can just swap out the EPROM to the proper one. if one exists (i'm more a chevy guy than an olds) get an HO prom for the 307 as it will allow more spark advance. that's if you want/need to use the stock dist and carb. if you want performance, go with a properly setup non-ecm/CCC carb and dist...and an olds 350ci.
i personally like having a knock sensor to avoid killing things. and somehow the chevy HO 305 eprom/ecm i have seems to be perfect for my build.

 

[dan2286]

Here is a good site to take a look at, http://www.robertpowersmotorsports.com/Technical_Info.html

 

[bill]

thanks for the info fellas, I am planing to use a non ecm carb and a non computer HEI distributor. I just wanna make sure that the old motor will run right in the newer car without a mess under the hood. I've seen it done in other cars but never had the chance to ask the owner how it was done or what was used or left off. Ideally, Id like the car to look and drive as it would if it was a stock car only with a 350 instead of a 3.8 v6. Im gonna try to use the original a/c set up if I can find the right brackets for the compressor. Thanks again!

 

[85 Cutlass Brougham]

The computer uses an add on subharness which plugs into a 4 pin plug on a computer HEI.The non computer HEI uses a single wire that is pink to run it. The pink wire runs off the ignition switch and has no connection to the 4 pin computer plug. So, it will just be a plug and play operation. You can leave the computer harness in place or take it out, it really makes no difference if you are not running an computer HEI or Quadrajet.

 

[joe_padavano]

The old motor neither knows nor cares what year chassis it is in. As noted above, so long as the HEI gets +12V from the ignition switch, it will run just fine. More importantly, if you're not using the computer Qjet, you CAN'T use the computer HEI, since the computer needs the TPS, MAP, and temp signals to figure out the advance curve.