Swapping out OEM distributor with HEI distributor

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boloboss

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I recently swapped out my OEM distributor with a HEI distributor. However, I noticed on the HEI distributor there's not a harness wire as on the OEM distributor. Although when I hooked up the new distributor without anything going to that wiring harness, everything is working fine. I'm trying to determine what is that wiring harness for on the OEM district
And omit this hookup to their wiring harness
The red distributor is the new HEI swap. The gray is the OEM distributor
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PrairieDrifter

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Should be esc (electronic spark control) you don't need it. There should be a box under the dash. If it wasn't already moved.
 
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Ricko1966

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That harness was for the knock sensor computer ESC (electronic spark control)Your old distributor was HEI and knock sensor too,and also curved for your engine,assuming your engine is stock. If the factory distributor and knock sensor was working I'd prefer it on a stock truck. The knock sensor will allow you to run more timing because when it senses knock it starts pulling timing to eliminate it. A distributor without knock sensor you need to find the point just below knock and retard just a little more. Even on a performance motor my personal choice would be knock sensor recurved. If the old system had a problem I can see replacing it,kind of. But replacing it just for fun,wouldn't be my choice.
 
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fast 99

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Used GM is better than new. Where was that replacement distributor made?
 
TotalyHucked

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As stated, that harness plug you're referring to is for the ESC computer (electronic spark control). The harness goes through the firewall and into a brain box that's mounted on the underside of the cowl, above the HVAC box. You're fine to run without it. Mine died and left me stranded in a parking lot in my '85. Once it cooled off, the truck would run so I limped it home, me and my dad yanked out the ESC dizzy and stabbed in a regular HEI. Reset the timing, adjusted the carb and touch and the truck drove so much better after that. 40yr old electronics are pretty much on their last leg by now
 
boloboss

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Do I loose any power or spark not running the (esc)
Here's some recent pics of (HER) my 84 C10....well that's what the truck is referred to by my wife, because I spend the bank on (HER)
 

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boloboss

boloboss

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The distributor is made by KMJ performance. The brand is called assault Racing. They're out of Iowa @fast 99
 
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boloboss said:
Do I loose any power or spark not running the (esc)
Here's some recent pics of (HER) my 84 C10....well that's what the truck is referred to by my wife, because I spend the bank on (HER)
Click to expand...
If it was working correctly,yes you are giving up some power,and some gas milage,if it wasn't working right,you will be gaining.
 
boloboss

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How would I tell if ithe old distributor wasn't working properly? I put in the new distributor, It seems like I'm getting more power as far as gas mileage. It seemed like it was burning a lot of gas before with the old distributor. I haven't determined the new gas mileage yet. @Ricko1966
 
Bextreme04

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Ricko1966 said:
If it was working correctly,yes you are giving up some power,and some gas milage,if it wasn't working right,you will be gaining.
Click to expand...
Only if he still had a stock 305. AFAIK the 350 never has ESC, it was only a stopgap for the piss poor head design of the 305 that made them an absolute dog with the small amount of timing you would need to set for it to not knock. If the engine has been replaced for a reasonably worked over 350, the ESC and 305 spark curve would be absolutely terrible on it.
 
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Ricko1966

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boloboss said:
How would I tell if ithe old distributor wasn't working properly? I put in the new distributor, It seems like I'm getting more power as far as gas mileage. It seemed like it was burning a lot of gas before with the old distributor. I haven't determined the new gas mileage yet. @Ricko1966
Click to expand...
You already swapped,at this point I wouldn't worry about it. Other wise you would need to swap the old one back in and do some checking on it.. Don't throw out your old parts. You may need them in the future
 
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Bextreme04

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boloboss said:
How would I tell if ithe old distributor wasn't working properly? I put in the new distributor, It seems like I'm getting more power as far as gas mileage. It seemed like it was burning a lot of gas before with the old distributor. I haven't determined the new gas mileage yet. @Ricko1966
Click to expand...
Do you have a 350 now? Is it a stock 350 or somewhat warmed up? ESC was only on the 305 and it was necessary to get decent power and fuel mileage from them. If you now have even a stock 350 in it... you won't want the old 305 distributor. The spark curve and ESC will not work well on a 350.
 
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Ricko1966

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Bextreme04 said:
Only if he still had a stock 305. AFAIK the 350 never has ESC, it was only a stopgap for the piss poor head design of the 305 that made them an absolute dog with the small amount of timing you would need to set for it to not knock. If the engine has been replaced for a reasonably worked over 350, the ESC and 305 spark curve would be absolutely terrible on it.
Click to expand...
I disagree but,don't want to argue about.
 
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