Pinging under load

[plyroadking]

Well the '40 made the trip out to CA just fine, even did just under a thousand miles in one day. It got a consistent 20 mpg while running at 70-75 mph. However i noticed a pinging occurring when it was under a load going up a hill, at the next fuel stop i switched to a higher octane and the pinging went away. It is a '55 230 block and if i recall correctly the timing is susposed to be 3° advanced, which i set it to. Also when i rebuilt the motor i switched back to the original '40 distributer since it had a good vacuum advance module. So now I'm starting to wonder if the '40 distributer is advancing the timing too much? Can i just set the timing on the motor to 0° and go back to the lower octane?

[Don Coatney]

Suggest you check your point gap. Timing will change as the points age. I had a similar problem several years ago. I adjusted my points, set the timing to zero advance, and the car ran great with no pinging.

[greg g]

If you find your points are fine, just loosent he dizzy and retard it by smal increments till the ping disappears, then lock it down.

[Alshere59]

Sounds like a great trip but a little more information may be needed as there are a lot of things that come into play and you want to look at the bigger picture.

All of these can play a role.

Carbon, too high of compression for the octane fuel being used, too low of octane fuel for the compression, bad fuel/water in fuel, engine running too hot, inlet air into engine too hot, timing too advanced, air/fuel ratio too lean, lugging the engine around (driving up hills in 5th gear), spark plug heat range too hot for the compression.

So what is your gear ratio on your rear end? Overdrive? Maybe it was just to steep of a hill. Some mountains along that route from Iowa IIRC.

What does your plugs look like? Lean by chance or to hot of a range. Lots of guides to help reading spark plugs on the internet if needed.

What was your engine temps? Running a 180 degree thermostat?

You mentioned an engine rebuild, did you shave the head? Raise the compression. These older engines were built for a very low octane gas back then. I wouldn't think stock timing would cause your problems. Moose a member of this forum has a distributer machine if you think that may be needed. Also here is a long thread on timing and and old flatheads.

http://olskoolrodz.com/forum/showthread.php?t=47895

Anyway not trying to add to your to do list but just suggesting there are a lot of things to consider in addition to some of the suggestions already posted.. Hope it helps.

Al

Edited May 13, 2012 by Alshere59