number of pulses per revolution from HEI tach connection?
number of pulses per revolution from HEI tach connection?
(OP)
I'm setting up a PLC to run an experimental IC engine. I want to use the pulse output from a 6 cylinder GM HEI ignition. Anyone know how many pulses per revolution the HEI outputs?
Thanks!
Thanks!





RE: number of pulses per revolution from HEI tach connection?
Or is this a "trick" question?
RE: number of pulses per revolution from HEI tach connection?
RE: number of pulses per revolution from HEI tach connection?
Be aware that the reluctor output is not a typical logic pulse.
Also, BEWARE that GM has made a number of V6 engines on V8 production lines, with cylinder banks at 90 degrees to each other, some of which had uneven firing intervals (and tricky distributor phasing) and others of which had even firing intervals and odd-looking cranks.
Generic engine controls sold for natural gas engines are flexible enough to use a number of different inputs, but commonly take their speed signal from a magnetic prox probe looking at the starter ring gear teeth, and a #1TDC signal from a magnetic prox probe looking at a single hole in the flywheel rim.
Mike Halloran
Pembroke Pines, FL, USA
RE: number of pulses per revolution from HEI tach connection?
Thought about the flywheel option also. I've got 155 teeth on the flywheel, so adds "a little hair" to the math. The large radius of the flywheel does give a lot of room for accurate timing.
I'm building my own CNG controls. Guess I'm masochistic that way :)
RE: number of pulses per revolution from HEI tach connection?
I.e., I'd be wary of using an encoder on an engine, what with the delicate glass disc and small dimension optics inside and the usual instrument bearings on the shaft. YMMV.
BTW, those natural gas engines seemed to chronically misfire at low speed and low/zero load, the only way we could test the monsters, even with super high energy CD ignition. Old timers said it was the nature of the beast. YMMV.
Mike Halloran
Pembroke Pines, FL, USA
RE: number of pulses per revolution from HEI tach connection?
RE: number of pulses per revolution from HEI tach connection?
Mike Halloran
Pembroke Pines, FL, USA
RE: number of pulses per revolution from HEI tach connection?
Thanks!