Help with HEI - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Johngear67 · 09-08-2002, 03:25 PM

is there a web site that anyone knows that would give me all i need to know about the hei(got some problems)
changed the modulator and now it dies if dropped below 800rpm

*Zkast* · 09-08-2002, 03:50 PM

Do you have a DVOM (digital volt ohm meter)?
If so you can check out (what will probably be the cause) the pickup coil by unplugging it from the ignition module(two wire connector. Then, if the wires dont break lol, hook your DVOM leads to the 2 wires coming from the pickup module. Set your DVOM to an auto ranging AC scale. Have someone crank the engine over and watch to see if the pickup coil generates a AC voltage. If it doesnt or the voltage is not somewhat steady, you have a bad pickup coil.

What happens is over time the coil breaks down internaly and does not produce a good square wave pattern. The module doesn't know how to interpret the signal and fails to trigger the coil.

All this is based on the fact that you "Know" its not getting spark at lower RPM's. You can check that with a timing light. Point it at your hand while allowing the engine to die. If the light goes out before the engine is completly stopped turning... you've lost spark.

09-08-2002, 03:25 PM	#1
Johngear67 The Mighty Blue Bottle Join Date: Mar 2001 Location: Canada Sk Posts: 134	Help with HEI is there a web site that anyone knows that would give me all i need to know about the hei(got some problems) changed the modulator and now it dies if dropped below 800rpm __________________ 1967 Chevy C 10 Custom 350 780 cfm 467 lift 278 dur ported&pollished 2400 stall 350TH B&M shifter 175 shot of nitrious

09-08-2002, 03:50 PM	#2
Zkast Account Suspended Join Date: May 2002 Location: Olathe, Kansas Posts: 929	Do you have a DVOM (digital volt ohm meter)? If so you can check out (what will probably be the cause) the pickup coil by unplugging it from the ignition module(two wire connector. Then, if the wires dont break lol, hook your DVOM leads to the 2 wires coming from the pickup module. Set your DVOM to an auto ranging AC scale. Have someone crank the engine over and watch to see if the pickup coil generates a AC voltage. If it doesnt or the voltage is not somewhat steady, you have a bad pickup coil. What happens is over time the coil breaks down internaly and does not produce a good square wave pattern. The module doesn't know how to interpret the signal and fails to trigger the coil. All this is based on the fact that you "Know" its not getting spark at lower RPM's. You can check that with a timing light. Point it at your hand while allowing the engine to die. If the light goes out before the engine is completly stopped turning... you've lost spark.



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