base timing keeps advancing by itself...

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Well that turned out to be a rabbit trail. Rebuilt distributor, reinstalled in car... and EXACTLY REPLICATED the issue. Warmed up, set base timing to 12, went for a spirited drive, started rattling at 2k-2500... checked timing again.. up to 22.

At this point, evidence seems to be pointing to timing chain/cam gear.
 
Did you check the advance sprAngs? Sounds like they might be weak.
 
If the inter shaft was spinning in the gear, you would get no oil pressure.....

I never use Pertronix products because of the BS. They claim the Ignitor 1 doubles the secondary voltage. It doesn't & voltage doesn't change, assuming the same coil is used.
Not sure if that version uses a slotted wheel/window for triggering, but if it does I'll bet it is moving & changing the timing.
 
If anything was slipping slightly, wouldn't that retard the ignition? Not advance it? It sounds like it's adding 10 degrees pretty frequently. Has it made a full circle?

Something odd is going on. If you shut off and let it cool overnight, does the timing stay advanced? Or does it go back to normal? Electronics can do strange things when hot. That would be my first suspect.

Have you verified the ignition module pickup wiring isn't backwards? It's easy to do, and these days there are units that come out of the box incorrect (I haven't seen it, but reputable people have posted about it). From memory, whichever orientation causes the least advanced condition is the right one.

Last thought: I know OP is sure it's actually gaining advance. But I'd expect similar behavior if the idle mix is lean and the idle hangs a bit after a drive. Higher rpm makes for more advance.. I would try something. The next time it does this, don't move the distributor, instead richen the idle mix a tad and see what happens. Or even drop the idle with the screw and see if the advance goes back to what it was set at. I have an engine that occasionally hangs before the idle drops back to normal. I sometimes just slip the clutch a bit to lug it down and then it'll stay there. Ever since I readjusted the electric fan switch to come on sooner it, it doesn't do it.
 
It is really weird and it seems the op is actually getting timing advance because he says it begins pinging (and doesn’t ping when it’s set correctly) and idling high and that’s what leads him to check it. Certainly doesn’t seem like a carb issue to me.
 
What stuck me as really odd is he has to back up the distributor further than his original marks to get back down to his initial. That would suggest some fixed relationship (rotor, pickup, drive tang, intermediate shaft) is changing.
 
Phreakish said:
If anything was slipping slightly, wouldn't that retard the ignition? Not advance it? It sounds like it's adding 10degrees pretty frequently. Has it made a full circle?

Something odd is going on. If you shut off and let it cool overnight, does the timing stay advanced? Or does it go back to normal? Electronics can do strange things when hot. That would be my first suspect.

Have you verified the ignition module pickup wiring isn't backwards? It's easy to do, and these days there are units that come out of the box incorrect (I haven't seen it, but reputable people have posted about it). From memory, whichever orientation causes the least advanced condition is the right one.

Last thought: I know OP is sure it's actually gaining advance. But I'd expect similar behavior if the idle mix is lean and the idle hangs a bit after a drive. Higher rpm makes for more advance.. I would try something. The next time it does this, don't move the distributor, instead richen the idle mix a tad and see what happens. Or even drop the idle with the screw and see if the advance goes back to what it was set at. I have an engine that occasionally hangs before the idle drops back to normal. I sometimes just slip the clutch a bit to lug it down and then it'll stay there. Ever since I readjusted the electric fan switch to come on sooner it, it doesn't do it.
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Correct. As the timing chain stretches, timing is retarded. I think looking at the timing chain here is a waste of time. I would try another distributor, as I believe that's where the problem lies.
 
TT5.9mag said:
What stuck me as really odd is he has to back up the distributor further than his original marks to get back down to his initial. That would suggest some fixed relationship (rotor, pickup, drive tang, intermediate shaft) is changing.
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Right! It's in the distributor I believe. It sure is trying to tell him that anyway from what I can figure.
 
Weird Issue Joe just saw it. I have never seen one of the big pins come loose but that would definately cause issues. If that does not fix it look at the oil pump drive gear see if it is worn, also what shape is your timing chain in? OK you liminthe the distributor by changing it out and same isseu. Weird.
 
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I would also be looking VERY closely at the outer ring on the balancer.
 
I have seen points distributors do that if they are not grounded to the block, but NA here with a petronix in it
 
But see, the outer ring on the balancer slipping will not affect timing, so that will not explain why it will start spark knocking after the timing has been reset. That's only a function of the distributor. It's pretty clear to me that's where the problem lies.
 
Dave999 said:
are you sure the petronix collar isn't moving round the shaft? it shouldn't.....
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That would be hard to make happen, The rotor fits the contorr into the ring then it goes on the shaft.
 
Years ago I had a car come into the shop that was changed from a lean burn to a regular electronic with parts from an auto wrecker. It kept retarding the timing. I swapped out to a dist I had laying around and it was good after that.I had tried 2 other ecu’s. They never made any difference. Kim
 
Pertronix collar is tight and wires are in correct order, have been using same unit for years. But the issue does seem to correspond to heat… maybe it is electrical somehow.

As far as distributor advance springs, they looked fine. One heavy, one light, working as advertised. I guess i can pull the distributor and send it to Ray to check it out.

So far leading theories:
1) pertronix unit failing with heat. It is a simple magnetic trigger, no ecu so i dont see how this could happen. Although i have noticed cap contacts fouling very quickly lately. Plugs spotless. 0.040” gap, pertronix coil. Air gap set to factory spec. Mag pickup is firmly attached to vac advance can with no slop.
2) weak advance springs. They look fine, and this doesnt make sense as to why the engine is 10degrees retarded cold, and advances as it heats up.
3) cam gear is loose. No clue what timing set the engine builder used. The only thing I could think of is that maybe they left out the Woodruff key and it was just the bolt holding the gear on? But still as others have mentioned wouldn’t the cam retard under load, not advance? Also, why would it return back when the engine cools off. Although this would explain the erratic timing mark at idle, only moving a a couple degrees but still it should be rock solid at idle, right?
 
“Also, why would it return back when the engine cools off.”

Wait a second. The timing returns to your original base setting by itself after it cools off?
 
TT5.9mag said:
“Also, why would it return back when the engine cools off.”

Wait a second. The timing returns to your original base setting by itself after it cools off?
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Yeah exactly!!! I don’t believe that’s been mentioned before.

It’s an electronic issue if it returns to normal when cold, if it was mechanical it wouldn’t do that at all.
 
72bluNblu said:
Yeah exactly!!! I don’t believe that’s been mentioned before.

It’s an electronic issue if it returns to normal when cold, if it was mechanical it wouldn’t do that at all.
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Yes sir. That is a handy little piece of left out information.
 
smokinnjokin said:
Well that turned out to be a rabbit trail. Rebuilt distributor, reinstalled in car... and EXACTLY REPLICATED the issue. Warmed up, set base timing to 12, went for a spirited drive, started rattling at 2k-2500... checked timing again.. up to 22.

At this point, evidence seems to be pointing to timing chain/cam gear.
Click to expand...
OK it followed using another distributor, I am assuming a points one sice all the electronics are in a petronix. Really a weird one Cooling down sure seems to be a electrical issue. What exactly is in your ignition ststem from the ignition power all the way?

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halifaxhops said:
OK it followed using another distributor, I am assuming a points one sice all the electronics are in a petronix. Really a weird one Cooling down sure seems to be a electrical issue. What exactly is in your ignition ststem from the ignition power all the way?

View attachment 1715944406
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I didn't take it that way. I took it to mean he rebuilt the distributor he had, not that he installed a rebuilt unit. Communication works so much better when complete and correct sentences are used.
 
halifaxhops said:
OK it followed using another distributor, I am assuming a points one sice all the electronics are in a petronix. Really a weird one Cooling down sure seems to be a electrical issue. What exactly is in your ignition ststem from the ignition power all the way?

View attachment 1715944406
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I think "another distributor" was used to replace/repair some parts on the suspect one? That's how I understood it. Still, it reinforces an electrical issue.

I still suspect there's not a real problem and the idle is just hanging higher when 'hot' (versus 'warm') which keeps more advance in it. Insufficient cruise advance can cause the chambers/plugs/valves to run much hotter which will also raise the idle speed after a drive. Higher idle will pull advance in and keep the idle high.

Super stout springs would help so that it can advance at slightly higher rpm but ensure no advance at idle up to say 1800+ rpm.

Or increase the all-in timing (I think he said it was 24? But it's unclear), or richen the idle mix a bit - but those won't directly confirm or disconfirm what I'm suggesting.
 
@Phreakish that would not explain why he has to back up the distributor further than it was previously.
 
Yeah that info would help. Just weird two doing the same thing so kind of getting away from the distrib but not much else but the ballast if he put it back in. Like the slipped balancer but it seems the timing is actually moving. Weird one he can send it to me again he knows I got he rides and will beat the hell out of it hot and cold to confirm or eliminate the distributor. Not thinking really anythin else. if there is no othe box in the system. Was a points distrib converte to a Petronix I they usually just fail and wont work if they go bad. Never heard this one before. And also turned it back twice so that all adds up on the position of the distributor related to say the oil pump drive off of the cam. Not much inside a distributor that can physiclally change like that. Really a weird one here Guys.
 
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