blown engine from HEI dist module

[boatmoniepit]

Has anybody had a problem with the 7 pin HEI module turning up the timing on its own. This caused my 502 engine to predetenate and melted 6 psitons. The computor and diag scanner showed proper timing but a timing light showed very advanced timing and it was determined that the module was the culprit. The knock sensor and computor were unable to decrease the timing. Just where does the module get the signal to advance or retard timing?

 

[bruceb58]

Re: blown engine from HEI dist module

That's a bummer. Couldn't hear it at all?

Module should base timing on RPM and knock sensor(if equipped).

 

[Bondo]

Re: blown engine from HEI dist module

Just where does the module get the signal to advance or retard timing?

Ayuh,... That's a New 1 for Me,... The module gets it's signals from the 'puter I believe...

 

[ken_23434]

Re: blown engine from HEI dist module

I am not familiar with your engine, so I might be off base but ...

All the engines I have messed with always have the timing set using a timing light. Frequently, the computer input to the distributor is disconnected to set the base timing also. There was a plug near the distributor that would cut out the advance signal, but leaving the rest of the ignition module powered up.

I am not familiar with a system that sets the timing FROM the computer.

How was it determined that the timing was too far advanced? Did they run the engine with the 6 burnt pistons to check the timing?

 

[Glastron_V210]

Re: blown engine from HEI dist module

It gets a signal from the ecm. The base timing is set without this input connected (Grounded), then when the signal is added it controlls the timing from this point upwards.

Some guys will advance the base timing a couple of degrees, thus advancing it throughout the entire range.

Chay

 

[Glastron_V210]

Re: blown engine from HEI dist module

I should say this is with post ecm HEI distributors. There are some (Like the one on my boat) which I think predate the ecms. These ones advance based on mechanical pickups, but I think they are 4 or 5 poin, not the computer controlled 7 pin.

Chay

 

[mylesm260]

Re: blown engine from HEI dist module

I only have experience with the 4 Pin HEI modules, and I know for certain that they got their signal to fire externally (from ECU).


The roll of the 4 pin modules was just to act as a glorified ignition driver, handling the current and the dwell to the coil.