Square wave trigger signal with HEI module?
01-02-20, 01:52 PM
#1
Square wave trigger signal with HEI module?
HI guys, I have a GSL-SE and am finishing up the DLIDFIS conversion. I'll eventually be going to dual trailing as well and replacing my dizzy with an S4 CAS that I have on hand. The reason is to tidy up the engine bay and make future standalone conversion easier.
My concern is whether the square wave output from the digital S4 CAS will properly trigger the HEI unit which is expecting an analog signal. ...HEIs have built in A-D converters afaik and I'm not sure what inputting an already digitized waveform into it would do.
My thought process is that they both trigger 12V, just the waveform is different right?
I won't be heartbroken if I have to keep my distributor even though it'll look silly without ignition wires. I know most standalones let you choose reluctor or hall trigger, so when the time comes I'm not screwed without the CAS, but would be nice to get that dizzy out if I can...
Has anybody done this? Sorry if this has been asked a bunch but my search terms didn't come up with anything useful.
My concern is whether the square wave output from the digital S4 CAS will properly trigger the HEI unit which is expecting an analog signal. ...HEIs have built in A-D converters afaik and I'm not sure what inputting an already digitized waveform into it would do.
My thought process is that they both trigger 12V, just the waveform is different right?
I won't be heartbroken if I have to keep my distributor even though it'll look silly without ignition wires. I know most standalones let you choose reluctor or hall trigger, so when the time comes I'm not screwed without the CAS, but would be nice to get that dizzy out if I can...
Has anybody done this? Sorry if this has been asked a bunch but my search terms didn't come up with anything useful.
01-02-20, 03:33 PM
#2
I think I figured it out, at least according to the WIKI section on High Energy Ignition:
"..There are four basic types of HEI control modules: four-, five-, seven-, and eight-pin. The four-pin module was used on carbureted engines and uses conventional mechanical timing controls (vacuum and centrifugal advance mechanisms). The five-pin module was introduced in 1978 and was an early attempt at electronic timing control; it contains a provision for connecting a knock sensor. The seven- and eight-pin modules are used on early computer-controlled engines. The seven- and eight-pin modules contain no mechanical timing control mechanisms as the computer controls ignition timing."
I have 4-pin HEI ignition modules, so it looks like the S4 CAS is gonna stay in the S4 parts box. My 4-pin module is expecting an analog signal and not a digital signal like I thought originally.
"..There are four basic types of HEI control modules: four-, five-, seven-, and eight-pin. The four-pin module was used on carbureted engines and uses conventional mechanical timing controls (vacuum and centrifugal advance mechanisms). The five-pin module was introduced in 1978 and was an early attempt at electronic timing control; it contains a provision for connecting a knock sensor. The seven- and eight-pin modules are used on early computer-controlled engines. The seven- and eight-pin modules contain no mechanical timing control mechanisms as the computer controls ignition timing."
I have 4-pin HEI ignition modules, so it looks like the S4 CAS is gonna stay in the S4 parts box. My 4-pin module is expecting an analog signal and not a digital signal like I thought originally.
Thread
Thread Starter
Forum
Replies
Last Post