Okay-I see what we're doing now. Now,the NEXT dumb question;What engines do I need to source what parts from? I have a Chevy six HEI distributor I've already modified to fit the 302 GMC motor;will this work as a base for the 8 pin module and related components?
Speed
sounds like youre halfway there with the dizzy simple module swap and its ready
Cool-so if I use the big distributor does the 8 pin bolt in where the original was or do I need to drill new holes etc.? Then,what ECM would I need-the one that went with the TBI unit I plan to use?
Speed
The 4 pin module and 7 pin module will fit in the same holes. (Top two modules in the pic below)
7 Pin Module is used with a Large Cap HEI that has the ignition coil in the cap.
8 Pin Module is used with a Small Cap HEI that has a remote mounted ignition coil.
dave w
Last edited by dave w; 12-10-2014 at 10:16 AM.
^^ Nice picture! Very good comparison.
You may need to cut a small notch into the distributor to accommodate a plug for the additional wires to the computer. The part number I gave is an aftermarket module and it's used for both six cylinder and eight cylinder engines. The OEM listed different modules. Originally, large cap HEI distributors with clockwise rotation and 7 pin modules were found on 229 Chevrolet engines and 238 even fire Buick engines with CCC systems (computerized carburetor) from around '81 to roughly '84. You may be able to use a 7 pin module from a V8 car. There are likely to be some differences in dwell time and spark advance when the computer is not controlling timing, at least with the OEM parts. But it may not be noticeable. I would expect the V8 wiring harness could be made to work in a pinch although I really try to get everything from the original applications because you just never know what subtle differences you'll find.Originally Posted by Speedking
I may be late to this party, but why not just use the CCC HEI from a 4.1L I6 from say a California model of a 1984 G20 van?? I believe it is AC Delco # 88864755
"I may be late to this party, but why not just use the CCC HEI from a 4.1L I6 from say a California model of a 1984 G20 van?? I believe it is AC Delco # 88864755 "
I'll check that out;I'm discovering several different shaft lengths,depending on what I use. A late 70's 250 distributor is too long and needs the the shaft cut and re-shaped to drive the oil pump,and needs the drive gear moved and drilled and re-pinned. I have an HEI distributor from a 4.3 (?),but it's just too short. Then I have a points distributor from an early 70's 292 that's only about 1/4 inch too short;not sure WHAT to make of THAT. It appears whatever distributor I choose will need to have the housing modified at the base,the shaft will need to be lengthened or shortened,the end will need to be cut to a "blade" style to match the oil pump,the drive gear will need to be moved and/or replaced,and it may be necessary to be "creative" with fitting a suitable module and wiring.
"I really try to get everything from the original applications because you just never know what subtle differences you'll find."
I'm with ya on that.
More measuring,re-designing,configuring and wondering why I decided to do this will be ensuing.
Thanks for all your help,ideas and information-none of it will go to waste. The truck is currently about 15 miles away,stricken down with some burnt wiring (THANKS,mice!),but I have what parts I need to retrieve it. I'll be doing that as soon as the ground firms up enough to drive it out.
Speed
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