Ignition advance specs?

[Petros]

You do not need water injection to avoid ping, you need to find out what is not working properly and fix it. If the engine is de-carboned, and you have ping, it is either running hot, running lean, or has a vac leak, or something is causing the timing to be off (mis-set, or vac advance connected wrong). find the problem and the ping will go away.

If you are running high compression, the water injection might allow you to run regular instead of premium fuel. It is not a substitute for a properly running engine.

[dlb]

petros, i hear you. i want my engine working properly for sure and am slowly getting closer to figuring it out. the water injection just sounds like a neat idea that i'm unfamiliar with. one day if i'm feeling adventurous i might consider it but right now the priority is definitely to find out the root cause of the ping.

on that note, disconnected the PCV valve from the intake manifold port (let the valve vent to the atmosphere, did not block it) and that didn't help. currently have the vac adv disconnected and so far seems good. if this fixes the problem, i will look further into both the mechanical and vac advance for problems. fingers crossed!

[4wdchico]

petros, i hear you. i want my engine working properly for sure and am slowly getting closer to figuring it out. the water injection just sounds like a neat idea that i'm unfamiliar with. one day if i'm feeling adventurous i might consider it but right now the priority is definitely to find out the root cause of the ping.

on that note, disconnected the PCV valve from the intake manifold port (let the valve vent to the atmosphere, did not block it) and that didn't help. currently have the vac adv disconnected and so far seems good. if this fixes the problem, i will look further into both the mechanical and vac advance for problems. fingers crossed!

dlb:

If you do decide to run without any vac advance, you must tune by ear to an acceptable very low level of ping. Without doing so will most likely result in your engine not having nearly enough ignition advance at highway cruise conditions. Not enough ignition advance for any given condition will result in poor fuel economy as good part of the burning fuel mix will be exiting past the exhaust valves. This will also shorten the life of the exhaust valves. But you will never be able to optimize your ignition timing for all conditions w/o both vac advance canisters functioning, as the factory engineers intended, as you will have to choose between advancing the timing a bunch for optimum steady state cruise, and then the the engine will ping plenty at WOT, or you can choose to set the timing for less advance to be just short of ping at WOT and this will result in not enough advance at steady state cruise.

Have you made sure that you do not have a vac leak from the power brake booster?

No, you absolutely do not need water injection. However, having it will leave you secure in the fact that your combustion chambers are as clean as they can be at all times. After an initial clean up period that is. A big advantage, that I have not yet mentioned about water injection, is that you can advance the overall ignition timing for better fuel economy and better power.

[dlb]

yo. don't worry, i realize that finding the vac advance to be causing the ping and disconnecting it is not the final solution. it's just a means of narrowing down where the problem is. like i think i've mentioned, i wish there was a FSM spec for total advance at a certain RPM so that i could easily determine if something is just over-advancing, but since i can't find that, this is the next best way i can think of to determine if the problem is in the vac advance system.

i'm assuming that the power brake booster is the hose that leads from the brake booster to the port at the rear of the intake manifold. am i right? if so, it has checked out fine.

[4wdchico]

yo. don't worry, i realize that finding the vac advance to be causing the ping and disconnecting it is not the final solution. it's just a means of narrowing down where the problem is. like i think i've mentioned, i wish there was a FSM spec for total advance at a certain RPM so that i could easily determine if something is just over-advancing, but since i can't find that, this is the next best way i can think of to determine if the problem is in the vac advance system.

i'm assuming that the power brake booster is the hose that leads from the brake booster to the port at the rear of the intake manifold. am i right? if so, it has checked out fine.

Ok, the booster hose is good. Have also you verified that the power brake booster itself is does not have a vac leak? I have also seen vac leaks where the power brake vac source barb fitting is screwed into the rearmost intake manifold runner several times on carbed 3a/4a cars.

This bit that I posted a while back in another thread could be relevant to the issues that you are having:

To test the vac advance do not plug the diaphragm not having vac applied to it, doing this would somewhat hinder the tested diaphragm from moving the timing, provided both diaphragms can hold vac. Test both diaphragms and make sure they both will hold an applied vac for a 60-90 seconds.

The plate in the distributor that the trigger unit is mounted on does not pivot on a single pin as most points/trigger plates do in response to movement applied by the vacuum adv assembly. It rotates on a bunch of ball bearings arranged in an annular contact orientation on it's outside diameter. It is a good design when it is new, however after 25+ years the grease that the individual balls are packed with can harden and interfere with the rotation of the trigger mounting plate. I have had good luck removing the trigger plate & bearing assy. from the dizzy and then removing the trigger from it. I strongly suggest that you do not mess with the tiny sheet metal clips that hold the trigger plate's bearing assy together, just wash/flush out the old dirty hardened grease with your solvent of choice and then carefully apply a light viscosity grease back around the ball bearings with a fine tip needle applicator.

Of course, once you have pulled the trigger plate, it is the perfect time to clean up and re-grease the mechanical advance mechanism also.

If you end up needing a new vac advance unit Standard Motor Products p/n VC360 is the OE Nippon Denso unit. Last time I priced the VC360, Amazon had the best price.

If both your mechanical and vac ignition advance systems are sticky, pretty likely, you will be amazed how much better your motor will run once you have both systems working smoothly.

A good part of your pinging problem is possibly related to your vac advance not responding correctly to changes in engine load. This would mean providing enough total vac advance for conditions and responding smoothly to changes in engine vac. Having both vac canisters with vac applied to them at the same time the should yield roughly twice the total vac advance for a given amount of engine vac. So a small change in engine vac, AKA engine load, should provide about twice the change in total vac advance on a system where both vac canisters are working compared to a system where only one canister has vac applied. However, if the bearings that the ignition trigger backing plate rotate on are all gummed up with old grease, all bets are off.

[deejay1272]

Holy shit, DLB. I'm just catching up on this thread - lots of back 'n forth. Lots of good advice from others that probably know more about this than I do. However, true to form as a know-it-all, and recent victim of this same problem, I'll add my two cents now.

Here's how I dealt with the multiple vacuum advance nipple issue. I simply removed my dizzy all together, hooked up a clean vac hose and sucked away to a) check that my vac advance diaphragm was still in tact and b) determine which nipple actually advances the timing under high vacuum conditions. In my case, it was the bottom nipple, but I have seen variants on this! I encourage you to remove your dizzy, apply vacuum to a given vac port on the vac advancer and look at the little linkage arm inside the dizzy to see what port (when vacuum is applied) makes it move.

Once you figure this out, connect back to your gas filter as we've discussed in the past. If you can rule out the threat of vac leaks, then this ought to put you in the right place (so long as you reset timing as per the T4WD consensus 10* BTDC approach at no load, no vac advance).

Sorry if you've already tried this or some variation of this test. I hate to see you continue to struggle with this -- it would piss me of to no end if I were in your shoes.

[dlb]

hey gang. so i just finished a vac advance-free tank of gas and it wasn't great but it was ok: 10.77 km/L. this is with the timing advanced to 10* BTDC and absolutely no ping whatsoever. regardless, i checked both vac can ports just now and the lower (aka outer) one holds vacuum while the top does not. here's where i'm stumped though: if the can i was using held vacuum, why would i get ping? there is no vac leak that i can find and it's not over-advancing the timing. if i was using the can that leaks, this would make sense to me since it would be sucking air. all i can think of is that maybe there is a small leak in the lower can that only turns up during certain conditions.

anyway, i checked the dizzy in reggie (the project tercel) and both the cans in it hold vacuum so i'm going to swap it in to ron tomorrow. i'm sick from chinese food today and am weak as a kitten.

thanks to all for the help thus far.

[dlb]

Have also you verified that the power brake booster itself is does not have a vac leak?

ps - how would i check this? just spray carb cleaner over the entire booster?

[dlb]

bummer--swapped in the dizzy with both vac advance cans in good shape and hooked them up to ported and manifold vacuum and the ping returned. i will get it warm tomorrow and just keep looking for vacuum leaks.

in related news, i also reset my fuel mixture to make sure it wasn't too lean and it was right on with what weber states it should be, the screw was exactly 2 turns out. no problems there.

[deejay1272]

Keep the faith, DLB. I'm looking forward to the day when I see that you've addressed all these problems and running free and clear of any ping. Good luck!

[danzo]

vac advance-free

.....

and absolutely no ping whatsoever.

So why not run it like this? I've been sans vac advance for a few weeks and it's working great. I should mention that at one point I thought the gas mpg was terrible due to the a/c on, but I just discovered the fuel was boiling. I could hear it through the air cleaner and fuel was actually seeping out where the carb meets the adapter. Time to reroute the fuel line/insulate it.

ps - how would i check this? just spray carb cleaner over the entire booster?

You can use propane also, or just hook up your vac pump and see if it holds vac.

i'm sick from chinese food today and am weak as a kitten.

Man that sucks, hope you feel better. Funny thing is I used to work at a Chinese restaurant while in school. They are notoriously dirty (ours got shut down by the health dept at one point), as they can't be bothered by silly rules and regulations.

[Petros]

ps - how would i check this? just spray carb cleaner over the entire booster?

with the engine idling pull the hose to the booster off (at the intake manifold end) and plug it. If the engine speed changes the booster leaks.

[dlb]

thanks danzo, i think it was my soy allergy coupled with eating copious amounts of the soy-rich chinese food that did it. no one else got ill. i thought i was avoiding the worst of it but apparently not!

i'd prefer to run with vac advance for the reasons 4WDC mentioned earlier in the thread. namely, without it, you have to find a middle of the road timing setting that is less than optimum for both idle/cruising and WOT. he also mentioned a greater likelihood of burning exhaust valves due to still burning fuel passing them. until i get this sorted out i will run without vac advance but i'm going to continue the search. i mean, what else would i do with my time if not this? relax, read, do something nice and fun?

[4wdchico]

bummer--swapped in the dizzy with both vac advance cans in good shape and hooked them up to ported and manifold vacuum and the ping returned. i will get it warm tomorrow and just keep looking for vacuum leaks.

in related news, i also reset my fuel mixture to make sure it wasn't too lean and it was right on with what weber states it should be, the screw was exactly 2 turns out. no problems there.

The ping is happening under hwy cruise & light accel conditions? My best guess. This is not necessarily a bummer, this shows that you now have more total vac advance than you had before as you have vac canisters pulling the timing forward. Now just adjust the timing, retard it slightly in this case, for your fuel and atmospheric conditions so that your car will just ping ever so slightly when accelerating very lightly from a hwy cruise under the hottest conditions that you are likely to see for a while. These longest days of the year make getting a hot day pretty easy.

By turning off the stereo and listing to the engine, an aware driver can adjust the speed, throttle position or gear selection to get around a very minor ping condition very easily. You will then have your maximum fuel economy under cruise conditions. Providing that your ball bearings that the trigger plate rotates on in the dizzy are moving smoothly that is.

[dlb]

the story continues. i disassembled my old dizzy to clean and regrease the advance mechanisms, as per 4WDC's instructions. some interesting things i found were

- the weights for the mech. adv. each have a little metal bushing that sits between them and their mounting pins on the governor shaft. on each of the dizzies i checked, these bushings are worn out with a good portion of the material missing. having no good new ones around (and surely being unable to order them), i just cleaned and regreased them and reused them.

- i could find no bearing assembly for the vac. adv. like 4WDC mentioned:

The plate in the distributor that the trigger unit is mounted on does not pivot on a single pin as most points/trigger plates do in response to movement applied by the vacuum adv assembly. It rotates on a bunch of ball bearings arranged in an annular contact orientation on it's outside diameter. It is a good design when it is new, however after 25+ years the grease that the individual balls are packed with can harden and interfere with the rotation of the trigger mounting plate. I have had good luck removing the trigger plate & bearing assy. from the dizzy and then removing the trigger from it. I strongly suggest that you do not mess with the tiny sheet metal clips that hold the trigger plate's bearing assy together, just wash/flush out the old dirty hardened grease with your solvent of choice and then carefully apply a light viscosity grease back around the ball bearings with a fine tip needle applicator.

what i found was that the ring of the trigger plate was just solid metal which was greased and slid down the governor shaft. so, as above, i just cleaned and regreased the contacting parts. it worked noticeably smoother afterward.

- after reassembling the dizzy, putting it back in the car, setting the timing to stock 5* BTDC, and hooking up the vac adv, the timing did not advance to 13* like the manual states it should...it jumped up to about 25*. clearly, the grease i used must be way too light. i took it for a drive anyway since i had just spent a bunch of time on it and the peppiness made it fun to drive but it pinged like crazy, obv.

so i disconnected the vac adv again and am still running without it. i'll keep working on it though.