Octane Booster

[Ernest]

My ZZ4 engine still has that pinging issue during mid throttle situations... i've given up with a mechanical distributor and now using a total electronic one by the name of progressive ignition, even with conservative timings, i still have the problem even when using 93octane(w/ that dreaded 10% ethenal), unless the ethenal is the problem and need to find straight 93octane, im using GM recomended spark plugs(MR43LTS - .040gap) and the carburator(SA770) is tuned correctly, im at a loss.

A couple of trusted mechanics i've talked to say its definately the gas after giving them full detail of the issue at hand, im not lQQking to use any type of pure race fuel, so its the octane booster im after to try out, but i am unsure which one to try since i've never had to use that stuff before.... any suggestions on which brand?

Thanks

 

[Mac442]

What timing are you at? These things like about 10 initial 36-38 all in at 3000/3200 ish.

 

[Built6spdMCSS]

Pull 2* of timing or fatten it up a hair. I tune all my stuff a hair fat to compensate for the ethanol gas. Runs hard.

 

[Ernest]

Im running with GMs recomendation timing for the ZZ4 motor... 10* initial, 32* total @ 3000rpm instead of GM's 4000rpm, that setting was for the mechanical distributor used, the 10*/32* info is currently set within the progression ignition distributor APP and as for the carburator, it has been richend up, stock front jets were 72, i went up to 75, and the stock rear jets were 75, i went up to 83, it does accelerate a little better at cruising speed since i richened it up, the SA770 should be plenty, no need to fatten it up any more IMO.

Funny thing is... when i used the mechanical distributor, the plugs had more of a correct tannish color after richening up the carb, which was a step in the right direction, but then i checked the plugs again after installing and running the progressive ignition distributor for 10miles, just light cruising, no hard acceleration or WOT runs, the plugs lost the tannish color and went back to an off whitish color like its running lean once again, as if i was running the stock front and rear jets in the carb in conjuction with using the mechanical distributor.

Figure i'll leave things the way i have it set, try a good octane booster and see if the pinging goes away... i can handle filling up with 93octane and then add the booster, its still cheaper than race gas.

 

[bracketchev1221]

The only one I’ve seen do well is actual Race Gas octane booster but it’s not cheap. It’s about $35 for 32 ounces. I think it will take 8 gallons of 93 and bump it to 100.

 

[Rktpwrd]

I was taught that the proper way to read plugs was to install a fresh set and then make a WOT run. Shut down immediately after, no idling and no part throttle. THEN pull them and read them. (I.E. at a dragstrip) Your no WOT pulls and part throttle cruising might be skewing your readings.
Just a thought.
Is your pinging only on part throttle acceleration or?? Have you made any WOT pulls yet?

 

[Ernest]

I understand the benefit of properly reading plugs after a WOT run, but because of the part throttle pinging, im affraid the pinging would get worse and possibly damage something internally if i pushed it. I really dont want to be out an engine with this parts scarecity going on, i want to continue driving the car for as long as possible till i can get another engine built for it, hoping sooner than later.

Figure when the engine is finally quiet at any and all throttle possitions... i'll take a stab and do at least one WOT run and see how that fairs.

 

[ELCAM]

To diagnose a part throttle problem you would get to the RPM that the trouble occurs and then shut it down and read the plugs.

Since you have the digital controlled distributor why not use it to find settings where it does not ping? GMs recommended settings may or may not be valid for that engine. That's the beauty of computer controlled engine management if a particular engine does not fit with in specs the computer can make it behave anyhow.

With the digital distributor you have some of that control, why not use it?

 

[1 RARE T]

1. Your gas may not be 93.
2. Distributor is going full advance too soon.
3. Part throttle vacuum leak.

No effin way it should knock with what you have.

Octane boost is a waste of money.

 

[64nailhead]

Pull 2* of timing or fatten it up a hair. I tune all my stuff a hair fat to compensate for the ethanol gas. Runs hard.

1. Your gas may not be 93.
2. Distributor is going full advance too soon.
3. Part throttle vacuum leak.

No effin way it should knock with what you have.

Octane boost is a waste of money.

These guys are correct.

You bought a distributor that can be easily tuned, so tune it (no sarcasm.) You indicated that it is pinging at light throttle - is this steady state driving, light throttle tip in or what? And of course what rpm and vacuum reading?

From what I’ve seen with the progression ignition it has a table for timing that is based off from vacuum and rpm. You need to find the cell(s) that you’re in when the issues occurs and pull a couple of degrees until it dissipates (this is what Built6spdMCSS is describing). The table looks like the table in the attached picture, correct?


Your 32 degrees at 3000 is a starting point, I would guess that is ultra conservative, but you have too much prior to 3000. The joy of what you bought is you can dial this in precisely.

Regarding reading the plugs, if you can hear and feel detonation, then reading those plugs is a waste of time because they won’t show poop other than detonation. And the detonation will affect color, strap reading and thread reading.

Can you attach a picture of your timing table?