What could pinging mean in terms of timing?

[pjoll84]

Hi everyone,

From what I’ve read on various forums when typing in “dodge 318 timing”… I see a lot of people recommending 8BTDC or 10 BTDC…

I’ve been farting around my with my moho and the 318 does not like anything past 5 degrees (shop manual says 2.5 BTDC) anything more and it starts pinging (or what I think is pinging, sounds like a bunch of rocks or nails rattling around a coffee can)

So in an effort to learn more about my rig… is there something mechanical that restricts my particular engine from enjoying more advance timing?

It’s a 1972 318 bone stock with a rebuilt auto line (Carter) bbd carb. Points and condenser (all new)

Is this where I would also need to adjust points to make up for the timing changes in the carb to eliminate pinging?

Can I convert to hei and eliminate points altogether?

 

[WileERobby]

1) yes, the distributor. 2) you adjust timing with a timing light and the distributor, not the carb that's the fuel system. 3) yes, there are several ways to convert to electronic ignition.

 

[71Beeper]

Or convert to the Chrysler electronic ignition system and eliminate the points.

 

[Jerry Hall]

Bone stock, follow the service manual.

 

[pjoll84]

Sorry I should have been more clear.

I’ve adjusted air/fuel mixture to where its reading 18-20 hg, I have used a timing light to get my initial timing (using all the right steps) and I’ve found that under load, anything over 5degrees, the engine starts pinging in high revs… which led me to the last bit about points and adjusting them to match the timing that I’ve changed… which i don’t know how to do… you tube time lol

 

[toolmanmike]

Sorry I should have been more clear.

I’ve adjusted air/fuel mixture to where its reading 18-20 hg, I have used a timing light to get my initial timing (using all the right steps) and I’ve found that under load, anything over 5degrees, the engine starts pinging in high revs… which led me to the last bit about points and adjusting them to match the timing that I’ve changed… which i don’t know how to do… you tube time lol

Points adjusting won't effect timing. (by much) New cap and rotor?

 

[pjoll84]

Bone stock, follow the service manual.

Thanks Jerry, manual states 2.5 +- so I’m assuming anywhere between 2.5 and 4 is ok? Seems a little gutless at the moment under load (but its also carrying a small apartment attached to it) so maybe thats just as good as it gets… still don’t know how to check if the points are gapped correctly.

heres a video of me stomping on it with the doghouse off… I was twisting the distributor as I was running it to eliminate the pinging lol

 

[pjoll84]

Points adjusting won't effect timing. (by much) New cap and rotor?

These are all good things to know, appreciate it. Yep, new cap, rotor, wires and spark plugs… (though the other thing I haven’t check is plug gap) which I realize is not inconsequential.

 

[lewtot184]

Probably has 30 crank degrees in the distributor so that plus 5 may be all the engine wants or needs. With the high vacuum reading the engine is pretty efficient. The more efficient the engine is the less total advance it needs.

 

[Rishi]

If you're car has been stored, and running on old fuel, there may be more pinging than usual. I think old fuel can cause more pinging than fresh fuel.

As most of us know, detonation, or pinging, occurs when trying to squeeze too much engine power from your fuel. We squeeze power by advancing the engine timing. Higher octane fuels allow us to run more advanced engine timings before pinging, compared to lower octane fuels.

Keep in mind, the factory 2.5-degrees BTDC setting, and (presuming) the 5-degrees ATDC, are engine timing starting points for the ignition timing set at or near idle.

Generally, this setting is the lowest your ignition timing will be at and slightly above idle. As the engine RPMs increase, mechanical and vacuum advances take place within the distributor. At some point, the timing gets advanced beyond your fuel's ability to handle the load.

Back in my youth, I would set the timing as advanced as I could get it without any pinging to be heard. When tuning to a higher octane fuel, I was obligated, more or less, to run that octane unless retarding the timing, some.

You can trying adding an octane booster to your fuel. Run some more tests to see if the pinging moves (on the timing curve)

 

[pjoll84]

If you're car has been stored, and running on old fuel, there may be more pinging than usual. I think old fuel can cause more pinging than fresh fuel.

As most of us know, detonation, or pinging, occurs when trying to squeeze too much engine power from your fuel. We squeeze power by advancing the engine timing. Higher octane fuels allow us to run more advanced engine timings before pinging, compared to lower octane fuels.

Keep in mind, the factory 2.5-degrees BTDC setting, and (presuming) the 5-degrees ATDC, are engine timing starting points for the ignition timing set at or near idle.

Generally, this setting is the lowest your ignition timing will be at and slightly above idle. As the engine RPMs increase, mechanical and vacuum advances take place within the distributor. At some point, the timing gets advanced beyond your fuel's ability to handle the load.

Back in my youth, I would set the timing as advanced as I could get it without any pinging to be heard. When tuning to a higher octane fuel, I was obligated, more or less, to run that octane unless retarding the timing, some.

You can trying adding an octane booster to your fuel. Run some more tests to see if the pinging moves (on the timing curve)

Appreciate this write up! I did wonder about the fuel but I’ve put in a fresh tank and a few cans of sea foam to clean anything up.

Since I had the opportunity to make micro adjustments to the dizzy whilst driving under load, I’ll shoot the timing gun and see where it ended up. Appreciate all the wisdom and advice!

 

[Jerry Hall]

Gap your points first as that will make a difference in timing.
.017-.018. Plugs gap at .35

 

[Coelacanth]

Back in my youth, I would set the timing as advanced as I could get it without any pinging to be heard.

That's exactly what I did; once I got the Edelbrock carb mostly adjusted where it wanted to be, one of us would be in the car giving the accelerator pedal a full press while the other would rotate the distributor until it just started pinging, then back it off until it went away. Probably not the ideal way to do it, but it worked.

 

[Don Frelier]

When I was younger and better looking the Chrysler small blocks suffered from bad intake valve seals.
The engine would pull in oil with the fuel mixture and emit blue smoke.
Particularly after parked when hot.
Running the engine this way generated carbon buildup pretty much everywhere.
Then the pinging would start.
I've seen small blocks so bad they would diesel and not shut off for minutes when hot.

One other thing (without pulling off the heads to clean up the carbon) is to adjust the vacuum advance spring inside the vacuum canister on the advance arm.
Most Chrysler distributors have an allen screw in there to apply a preload to the spring.
You do want to get rid of the pinging, even a Chrysler small block can be damaged running that way.

 

[PurpleBeeper]

One other thing…IF it only pings when you are already at highway speed and floor it, “maybe” your vacuum advance needs adjusting (Allen wrench inside hose connection nipple in distributor)

 

[Don Frelier]

My experience is that they ping at highway speed under light throttle and a load like up a grade.
Usually more throttle will alleviate the pinging. (vacuum drops and carb adds more fuel at the same time)

 

[lewtot184]

Looking at 1969 factory service manual for an example it showed a stock distributor with a 17 degree advance plate. That by it self is 34 degrees add 2.5 initial and that's 36.5. Also the intake valve closes at 50ABDC, that's early. If these numbers fit your application I wouldn't push it any further. Factory cast pistons break and pushing the timing is a big contributor.

 

[turbine68rt]

Points adjusting won't effect timing. (by much) New cap and rotor?

Point gap (dwell) absolutely affects timing. This is why dwell should always be set before timing is adjusted. The bigger the point gap (less dwell) the more the timing will advance.

 

[R413]

Yes a dwell change will change ignition timing. If he is not adjusting the points and only the timing then it is a moot point. Pun intended.

 

[toolmanmike]

Point gap (dwell) absolutely affects timing. This is why dwell should always be set before timing is adjusted. The bigger the point gap (less dwell) the more the timing will advance.

Yes, Timing does not effect dwell but dwell does effect timing but not by much. That's why I said (by much) in my post. Too little or too much dwell will make an engine run like crap or not at all. Detonation is usually not an issue with 2-4° initial regardless of where the dwell is set. If a few degrees of dwell would add, say 15° of timing, then we would have an issue. But it doesn't. The OP has other issues with the pinging other than his points set a little wrong.