Timing question

[fixkick]

PING (aka. detonation ) has many causes. hopefully not all at once,
1: too lean, (on a turbo, you blow the engine)
2: too far advanced spark. (in fact the distrib is tuned for the AFR used for above) (air fuel ratio) a dyno tune works best.
3: CR wrong, (too high) due to milling, wrong,, etc. ( needs more fuel and more retarded spark than stock to run)
4: EGR defeated the , stock 1991 car we have will ping under load, with the EGR disabled, due to the spark and fuel tables in side ECU are tuned for a working EGR. (not true on the JDM ECU, its has no EGR) did you defeat your EGR?
5: less that 87 octane fuel. (not possible here) it can ping.
6: other minor issues, (hot spots, pre-Igniton, wrong pistons (or hacks there) wrecking the top quench sections there.)
That quench stops detonations. not only this but Changing CR by milling can wreck the quench, effects.

(keep in mind, ive only the most basic idea of what you have, there, what parts, what modes, etc) G16 block and head, and non stock carb,
non stock vacuum advance.) (keep in mind the CARB and vacuum advance work as TEAM and are both wrong now,hummmmmm)
yes, (G16 but, what was total advance, ? in degrees, you measured)?
It be near impossible to check advance driving, and is why Custom EFI is done on a DYNO... just to that, and AFR.

on all distrib's like this, (most times we had the problem, years ago, for 3 reasons, boring out block for more displacement and higher compression ratios)
(bigger pistons, milled deck , milled heads all raise CR, in to the danger zone. over 750psi peak pressures, it will Detonate on REG GAS.
or someone hacked your distrib, and is all wrong inside..? (for sure vacuum advance is wrong, )

there are only 5 solutions.
1: move static timing point. (failed now at 0)
2: (mech advance)file the weights down or stronger springs.
3: add Vacuum limit stops (screws, or pins) to stop total advance, limits its travel, mechanically.
4: Do not use vacuum advance at all , defeat it, and use only RPM (might take changing #2 above )
5: upgrade to EFI or custom EFI and make your own tables. no more, advance allowed inside the distributor. (pure software, like all our 1991 here)
#5 would take creating a CMP signal. from inside old distributor to the outside, and then to ECU , like all 91+ cars here have.

the hard part is finding the OLD Suzuki tables on your engine , the distrib..
on better cars, we have that, we have both tables, or a unified table showing, the actual advance curves of both devices, (rpm and load)

this is the machine we used then to make the distributor behave.
https://www.youtube.com/watch?v=Hur8afp0oYo

back in the day,, distribs, can be stuck , hacked, or have wrong parts inside.
this machine we discovered these facts and corrected, it .
the other issue is the , carb vacuum ports, must work correctly too, or the vacuum advance or retard fails.

i can not see your vacuum setup in your photos.
the stock car had 2 vacuum ports. does the G13 vac have 2 or 1?
my guess ? just one? and where does it Go, show the exact location of your , vacuum line on the engine side (plenum>? or carb , if carb where?)

, so , when you start the engine, you have a vacuum line there, what is the vacuum at idle.
then gently raise idle speed, vacuum now?> then gun the throttle what is vacuum on that hose now? this checks to see if the port you are using is correct.
It seems to me the engine pings, with high vacuum (feathering means that) so that would say the Vacuum advance is setup all wrong.
at idle if you pull the vacuum line what does advance do? (pull it and pinch/plug the hose fast) see timing now? do nothing,advance or retard?




lots of issues
what is engine compression warm or hot, ? spec, is 170 but all mine did 185psi at sea-level, if you see why higher, maybe someone violated
the HEAD milling (shaved) rule and sent CR to moon, way too to high....

there are 3 kinds of advancing systems
1: tuned for max power.
2: tuned for max economy
3: tuned for smog, (that 2 nipple, vacuum servo tell me your car came like this) some use push/pull one nipple advances, other retards.

OCTANE ISSUES:
fuel our fuel here is a mixture of RON and MON, averaged.
Regular will PING easy, it's 87 octane here, called 92 RON, elsewhere, and is same fuel.
the 87 ping happens (CR causd, not wrong for bad spark timing) and the PING tells you , you exceeded the 750psi rule. for 87 octane.
you can not measure that pulse. its a lab test. but shows clearly what happens.
the purpose of spark is to keep that pulse at the right point, (time) at all RPMs and ALL loads., High loads need less advance.
at high engine loads the pressures is much higher, and needs less advance. (the load causes the natural peak to happen sooner is why)

Actual cylinder pressure below:
this shows the peak pressure happens about 15degrees, After TDC. the best point, is due to the rod acting like lever making more power.
if if the fuel detonates, (pings) the pressures are gigantic and can put hole in the piston(damage). this is for 87 octane.



what helps, is to see how EFI does this.
see the 3D map , no Dizzy can do this, and is why EFI can save 20% in fuel waste.
on a race engine, we'd use 12.5:1 AFR and more advance, for more power all the time.... and waste some fuel.

Please note the pressures are ABSOLUTE Vacuum not like any hand tool. on the left is WOT, on the right is fast driving then cut throttle and huge vacuum 100kPA = 29"HG vacuum wot is NO no vacuum or near zero on this engine, its 8 inches. or 30 kPa)

here is a 3d map, kPA 100 wide open throttle (1 atmosphere) absolute pressure, vacuum) the white numbers are ADVANCE.
65 kPa is about idle vacuum.


note how the advance, goes toward zero , under huge engines loads. see that 13?, in bottom right corner, this is max load.
The modern computer (ECU/PCM) uses this classic table, and then changes it if the knock sensor (a microphone) hears knock, (the stronger the knock the more retard)
your car will never do that..... it can't.( a zero brain engine)
what does that mean, that means carb cars are purposely DETUNED to not knock, when real hot, and under full load.

Some get confused on ABSOLUTE pressures,( using different systems world wide does not help)
consider, (sorry, if old hat to you)
next time you hear the radio weather news, listen to "barometer readings to day..." here its now my barometer on the wall reads 99 KpA (or 29.2 inches HG column) 100kPA = 1 bar
this is also called one atmosphere. at sealevel, (the highest road in world is 1/2 that)
or in the engine, near wide open throttle, a carb engine you can not have too big of carb because, at WOT pressure near 0 absolute, the carb does DEAD! (nozzle stalls)
EFI cures that. (no venturi to make happy!) this is why EFI makes more power. (that and perfect tables)

Does this help?

and a parting shot:
i'd not drive it pinging,,, not me, i'd at least defeat the vacuum advance.
then set static advance 8 degrees before TDC.
and ive no clue as to the original designers, advance strategies, (max power, min smog or what? and lacking the carb in hand , impossible to reverse engineer it now.)
the only clue to that , if lucky is buying an FSM matching your car.

same holds true with any G13 vacuum advance unit, im clueless there. but id try to get data off it. (testing)
one why is at idle to (strobe flashing on scale)
attach a hand vacuum pump (Mitivac™ and see what advance does?, a 0Hg and max vacuum.... no hose to carb, just tool to VAC pot.
then....
Test 2:
the stock distrib mech advance may put you into the ping zone at high rpm , up hills, all by its self.
this can be proved, with vacuum defeated and driving up a hill and lug engine. (5speed?)
on some cars, this happens and the VACUUM POT retards the spark on hill.s... (low vac = less advance)
but that is all theory, i have no FSM for market E95.

pitfall common in test 2
is the TUNER, finds to get full power , with mech, advance only, that now engine wont start.
he keeps setting static timing more farther advanced, until engine now has full power. and bam wont start.
cause, vacuum and mech advance work as a team.
In some shop.s the guy here recurved the whole mech advance so it would reach his desired, max advance, starting at 5degBTC, (so engine does not try to start backwards)
then uses bigger weights and weaker springs to attain his goal.

sorry for long post, but there are many paths to getting a custom engine, tune., and stop ping and get full power on demand.