Progression Ignition

[Ernest]

64nailhead.... no AFR guage and im running with a 6.5hg power valve, its a possibility that it could be opening late, who knows, but i do have a 10.5hg power valve to try, but that might open to early.

olds307 and 403... i was getting the pinging issue even with the mechanical distributor's brass cap and rotor, this progressive distributor has all new parts, so i cant see the brand new brass cap and rotor being the culprit.

According to holley... the way to set up a power valve, take what vacuum reading you get at idle(manual trans), divide by two to get the size you need, if its auto trans, take the idle reading in gear(drive), divide by two to get what size you need. My ZZ4 idles @ 800rpm in park with a reading of 17hg, in drive, it drops down to 14hg, so technically i need a 7hg power valve, but holley doesnt make that size, so i have to go one step lower to a 6.5hg power valve, so thats the one im currently using. I'll have to take the malibu out for another drive to actually see what the vacuum drops too with the progressive iginition APP and to see if its low enough to open the 6.5hg power valve when accelerating and under light load, not WOT.

 

[64nailhead]

Holley has given you a starting point imo. Now go drive the car with the same vacuum gauge hooked up. Either have it stuck to the windshield with the wiper or run it into the car via a hose long enough to go through the window. Pretty much somewhere that you can watch it while driving (without causing a traffic impediment lol.) Now go drive it and take note of the vacuum when the pinging starts or when any type of performance issue occurs. You'll find that it's extremely easy to see when the PV opens according to both the gauge and performance.

For example, if the problem is occurring at 7-8"of vacuum and you tap the throttle enough to open the blades to get your 6.5" PV to open and the problem disappears, then you know that you need a higher number power valve. And conversely, you might find just the opposite occurring. It's been my experience that a powerful engine needs a PV that opens sooner due to it doesn't take near the throttle opening to get the car to accelerate. And a lower power engine needs one that opens with more air (throttle plate opened). Like I mentioned, what Holley provided was an initial starting point.

Lastly (which you might already know), the PV is not intended for tuning hard stabs of the throttle, but rather slow changes in throttle pedal movements. The hard stabs are what the pump cam, squirter size and accelerator pump size are for. I messed around an entire summer commuting 110 miles daily while monitoring the vacuum gauge as I described above to dial in a low HP and low rpm setup. I was changing jets, squirters, accel pump and PV's multiple times per week all summer. And by the end of it I was convinced I wanted EFI and never wanted to fight with another Holley. But I did gain some understanding of how they work and what it takes to get one to work.

Good luck.

 

[Ernest]

Still tuning the carb... now running with a 9.5HG power valve and went one size leaner from factory setup, front and back on the 650cfm(0-80783C) jets, 67 to 66(front) and 73 to 72(rear), the engine is now a pinch more responsive, especially at highway speeds, barely on the throttle and it moves quickly, i did a quick 10mile stint, gas guage barely moves, using much less gas now it seems, no WOT tests yet, but still pinging lightly if i get on the accelerator a little heavy, if i ease into it slowly, its quiet, i guess im just stuck with it, even with the progression ignition, its nice, fun to tune with, but i have yet to figure it out entirely.

I've only got about 50miles on the progression unit, so i was curious on the wear pattern on the gear, it doesnt look exactly right to me compared to the GM08 distributor that was in the malibu when i got it and its been running in the engine for at least a year prior to me replacing it. Wth the progression unit, the engine takes 3-4 revolutions of the engine before it starts compared to the other one, like half a revolution of the engine and vroom, so for now, i put the GM08 back in the engine with its original internal parts, i removed the GM stuff, installed it in perfectly, lined it up with #1 cylinder and it fired up instantly without issue, timed it to 10degree initial, not sure what the total timing is or at what rpm, hooked up the adjustable vacuum advance can that i havent messed with to the ported source on the carb, took it for a test drive, feels no different than when i had the progressive unit installed, still light pinging as before.

The GM08 has a gear clearance of .045, somewhat excessive i know, but the gear has a really clean wear pattern, the progression gear clearance is dead on .020 like many say its supposed to be, the wear pattern looks likes crap to me and that just after 50miles, and the underside of the HEI cap where the carbon button is, the surrounding area looks like something was rotating on it, but the rotor looks fine, i did use a liberal amount of MSD gear break in lube on the new distributor gear, figured i installed everything correctly, so who knows what happened.

Pics of the progression unit gear still installed on the distributor, the underside of the HEI cap and the gear lube used... again, the GM08 parts look just about like new for being in the ZZ4 for at least a year.

 

[Dayzedandkonfuzed]

Thank you for sharing this.

I just added a part to my wishlist.

 

[Ernest]

What part might that be?