Dizzy problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jason952 · 05-10-2004, 11:00 AM

HI all,
I was putting the proform guts into my 85 HEI unit from the 305 that will go on the new 350. Apparently, my dizzy is "computer controlled", the module has one side with 2 prongs and one with 3. the proform kit has a module with only 2 prongs per side. they say it won't work. What are my options?? just new factory guts? should I convert it somehow? I have a 4 prong connector that goes from the firewall to the dizzy.

Does this mean that those fancy billet ones won't connect correctly either?? thanks!

jason

**swervin ervin** · 05-10-2004, 11:47 AM

Your old dizzy is not computer controlled. It's for the ESC (electronic spark control). This only controlled spark knock. I would do away with the ESC by installing a regular non ESC distributor. You may be able to convert the ESC one over with new guts, not sure. I'm guessing if you install the 4 pin module and do away with the 5th wire, it should be the same. I'm just not sure and don't have a old ESC distributor to look at.

Why not take a trip to the junkyard and find a non ESC HEI to put everything in. With a 350, you don't need the ESC junk anyway. 305's had them because they were so prone to spark knock, because of poor cylinder head design. GM's way of building crap and then building more crap to make the crap they just built work.

http://www.73-87.com/7387garage/drivetrain/escrepl.htm

jason952 · 05-10-2004, 07:02 PM

thanks, great link too

so I got it all to work right, so I now have a rebuilt dizzy with the proform kit, using all but the module. I got a new stock 5 pin module from the parts store. so for around 100 bucks, all the guts are new.

will the esc mess with the performance of my new motor, so long as it works ok? seems like it would only help if it started pinging (but it shouldn't)

jason

**swervin ervin** · 05-10-2004, 08:59 PM

The only thing the ESC does is help control spark knock. So as long as it's not spark knocking, it shouldn't have any effect on timing. A properly tuned 350 won't ping like a 305 anyway so it's not needed but I doubt it will mess with performance. Although the tip in vacuum switch will kick in when there is a sudden drop in vacuum such as happens when you stomp on the pedal. It it's working right I wouldn't worry too much about it.

Good job.

05-10-2004, 11:00 AM	#1
jason952 Registered User Join Date: Mar 2004 Posts: 65	Dizzy problem HI all, I was putting the proform guts into my 85 HEI unit from the 305 that will go on the new 350. Apparently, my dizzy is "computer controlled", the module has one side with 2 prongs and one with 3. the proform kit has a module with only 2 prongs per side. they say it won't work. What are my options?? just new factory guts? should I convert it somehow? I have a 4 prong connector that goes from the firewall to the dizzy. Does this mean that those fancy billet ones won't connect correctly either?? thanks! jason

05-10-2004, 11:47 AM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Your old dizzy is not computer controlled. It's for the ESC (electronic spark control). This only controlled spark knock. I would do away with the ESC by installing a regular non ESC distributor. You may be able to convert the ESC one over with new guts, not sure. I'm guessing if you install the 4 pin module and do away with the 5th wire, it should be the same. I'm just not sure and don't have a old ESC distributor to look at. Why not take a trip to the junkyard and find a non ESC HEI to put everything in. With a 350, you don't need the ESC junk anyway. 305's had them because they were so prone to spark knock, because of poor cylinder head design. GM's way of building crap and then building more crap to make the crap they just built work. http://www.73-87.com/7387garage/drivetrain/escrepl.htm __________________ Mike 1985 Chevy C-10

05-10-2004, 07:02 PM	#3
jason952 Registered User Join Date: Mar 2004 Posts: 65	thanks, great link too so I got it all to work right, so I now have a rebuilt dizzy with the proform kit, using all but the module. I got a new stock 5 pin module from the parts store. so for around 100 bucks, all the guts are new. will the esc mess with the performance of my new motor, so long as it works ok? seems like it would only help if it started pinging (but it shouldn't) jason

05-10-2004, 08:59 PM	#4
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	The only thing the ESC does is help control spark knock. So as long as it's not spark knocking, it shouldn't have any effect on timing. A properly tuned 350 won't ping like a 305 anyway so it's not needed but I doubt it will mess with performance. Although the tip in vacuum switch will kick in when there is a sudden drop in vacuum such as happens when you stomp on the pedal. It it's working right I wouldn't worry too much about it. Good job.



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