Geek's 65

I did a tune up on the ole girl cause I had picked up a bit of pinging that I attributed to the fine gas we get here in Winter and now seem to have an issue I can't explain. Originally I had set the distributor up so that the mechanical was all in (36 degrees advanced) at about 2800. At idle with no vacuum hooked up it would come in at 10 degrees and it ran great. So now I go to check it and find the dang thing shows that it's all in at about 1200 RPM and I did nothing to it (But it did explain why I was pinging. To think I would blame the gas. Jeesh) So I dug up my old spring kit for the distributor and put stiffer springs in. Barely helped. So I drilled out the weights to lighten them



Didn't help. It still is all in by about 1400 but when I drop back to idle, it sits right at 10 degrees. So unless I drive my car all the time at 3000RPM, it likes to ping.

Any suggestions on what would make this do that? Open to any and all ideas.

thanks ahead of time.

geek

5thvet

Geek,
Have to try shaving a little more weight off? Are the older springs you put back on heavy enough? Just throwing stuff out there to get things moving!
Don

Old Blazer

I assume your using a dial back timing light? Just for confirmation try another light.

Bud2

The springs look like the heavy ones, substantial reduction to the weights. Something else is going on Mate.

Bud.

Frankie the Fink

There is no way that you are getting another 24* of centrifugal timing in at 1400 RPM (basically a fast idle) with what you have done.

Which leads us elsewhere. Are you sure your breaker plate is not sticking (e.g. unable to retard the timing) and properly seated when installed? Is your harmonic balancer mark correct (e.g. two piece balancer isn't slipping)? Is your timing light on #1 plug and is that plug wired to the correct tower? Is your tach accurate? I'm assuming your timing light is set to the 8 cylinder position and accurate but do you have another one so you can double check your readings? Is your distributor clamp absolutely tight when you take the readings?

Unfortunately, when you find the real problem, I think you'll be trying to source new centrifugal weights as I think the drilling has probably made the ones you have now toast.

Geek's 65

Let's see
Yup I have a dial back light and am going to borrow a friends today to try and take that out of the hunt.

"There is no way that you are getting another 24* of centrifugal timing in at 1400 RPM (basically a fast idle) with what you have done.

Which leads us elsewhere. Are you sure your breaker plate is not sticking (e.g. unable to retard the timing) and properly seated when installed? Is your harmonic balancer mark correct (e.g. two piece balancer isn't slipping)? Is your timing light on #1 plug and is that plug wired to the correct tower? Is your tach accurate? I'm assuming your timing light is set to the 8 cylinder position and accurate but do you have another one so you can double check your readings? Is your distributor clamp absolutely tight when you take the readings?

Unfortunately, when you find the real problem, I think you'll be trying to source new centrifugal weights as I think the drilling has probably made the ones you have now toast."

I keep thinking the same thing - no way can I get that kind of advance with those springs and my "toasted" weights (I have a second set I got from somewhere which is why I was OK with drilling). Thought about the breaker plate but threw it out since when I let the idle drop back to 700 the timing goes back to 10 degrees. Using an old Sears dwell and tach meter that I have had for over 40 years but works well. It matches (within 100 RPM) the car's tach so I haven't questioned it. My friends Gucci timing light that I am borrowing has a tach function so will compare that too. Think today will be a day of pulling the dizzy and going through the whole thing. I had set the endplay to .010 when I rebuilt it last so that's another thing I wanted to check. Hadn't thought about the balancer being messed up. It's a good one (ATI) but will take a look and compare TDC between the mark and cylinder #1 just to be sure.

Appreciate all the ideas. Will let you know what I find.

Geek

Frankie the Fink

Please do let us know - this issue sounds like one to store in the 'ole memory banks for future reference !

If you were on the 'right' coast I have an extra distributor I would have let you borrow for troubleshooting

DansYellow66

I don't know how to explain that you believed it was working correctly before (advance in at 2800 rpm) but I suspect there could be a problem that your weights and the distributor shaft cam are mis-matched causing an all-in/all-out advance curve. That's kind of a guess but I don't see how else you could get that much additional advance with those springs over such a small rpm range.

mrg

The weights appear to be later style '69-'74 units mated to an early style 'football'. It doesn't appear so in the pic but could there be some slop or excessive running clearance to allow the auto cam to advance at such low rpm's before spring tension kicks in?.

Geek's 65

A timing light that doesn't set back correctly at anything over 1100 RPM. And so there I was ... chasing a setting that wasn't. Which explains why it worked when I set it up originally eight month ago but changed so radically now.

I connected my friends timing light that I borrowed to it and showed hardly any advance at all (gee I wonder why with drilled weights and stiff springs). Hooked mine back up and it showed all in at 1400. My light appeared to trigger OK (line on the balancer was sitting right on zero with the set back turned in) but when I added set back to the light, the line on the balancer didn't move. (Guess I should have tried that sooner eh?) Slow the engine down to lower than 1100 or so and the light indications started acting "normal" again.

So I put in my replacement weights, the black and silver spring combo, set it back up with my friend's light (but backed it off a couple degrees to compensate for the original issue which was that it had started to ping with our Winter gas) and it runs perfectly.

Thanks for all the inputs. Trust me I considered every one of them.

G

5thvet

G,
Glad you got that worked out. You hate to miss that Sunday morning cruise!!

Don

Old Blazer

Glad you found the issue. I didn't know Ca. gets winter blend gas too?! I also have a 40 yr old Sears analyzer and timing light I trust more than my Sun machine.

rongold

The easiest way out of this situation is to get a timing tape--available thru any speed parts supplier (They come in 6" & 8" balancer sizes), and then you can use any standard timing light, and NOT have to depend on the electronic circuitry in a dial-back-light. I have a dial back light ($400 Snap-On), and it never matches what the timing tape says--It's close, but never right on. The tape is always 100% accurate.

65tripleblack

I laminate a fresh timing tape to the balancer with every build. I use my 45 Y.O. Sears induction light. The tape never lies.

This same reasoning leads me to monitor my blood pressure with a stethoscope and an old fashioned sphygmomanometer rather than an automatic instrument. The automatics are "all over the place", but my ears never lie!