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Old 02-06-2023, 12:22 PM
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Default Where to Find Distributor Springs and Weights?

I want to try and put my points distributor (112008) close to original timing.

The last time I tried to get it running, idle timing was erratic and I want to eliminate the distributor as a possible source. I just replaced the 50-yr-old harmonic balancer as another possible contributor.

What are the stock weights or where can I look that up? Seems the info is available for HEI but I haven't found a reference for points distributor parts.

Is there anyone that sells used originals?

I even tried buying a used distributor off eBay and the weights were not stamped with codes so I don't trust they are original.

I attached some info I have about the stock timing and what I believe is the current setup with Crane springs. I want to make sure the mechanical advance does not kick in at idle and I don't trust these old measurements. I think they were guesses captured with the engine running and a sketchy tach reading. Maybe it's OK but I'd feel better knowing...

Mike
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  #2  
Old 02-06-2023, 12:32 PM
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If your timing is unstable with the stock heavy springs , or even with medium aftermarket springs you should first confirm that the advance shaft is not hanging up due to old harden factory lube.

Here's the overall timing curve from a typical high comp era 4 bbl motor.

Your chart and this chart should only be used as ball park due to today's fuel .
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Old 02-06-2023, 12:38 PM
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Originally Posted by 25stevem View Post
If your timing is unstable with the stock heavy springs , or even with medium aftermarket springs you should first confirm that the advance shaft is not hanging up due to old harden factory lube.
Distributor has been rebuilt and is in good shape.

I really don't know if the timing is still unstable but want to do what I can to eliminate possible causes for the bad history. It has been 4 years since I last tried to get it running and there were multiple issues.

If the Crane silver and blue springs are known to hold zero mechanical up to 800 or 900 rpm, then I guess I'm good?

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Old 02-06-2023, 04:44 PM
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25stevem -

I'm looking at the chart you shared and don't get it.

It shows 20 mechanical and 20 vacuum at 3000 rpm but the total is 50 ???

But it does show 0 mechanical at 1000 rpm. Is this typical for a stock distributor? If so, I definitely need stronger springs. I may have the originals from the used disty, but still hoping someone can help with the weight ID and source.

Thanks again

Mike

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Old 02-06-2023, 04:52 PM
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Originally Posted by Shiny View Post
25stevem -

I'm looking at the chart you shared and don't get it.

It shows 20 mechanical and 20 vacuum at 3000 rpm but the total is 50 ???

But it does show 0 mechanical at 1000 rpm. Is this typical for a stock distributor? If so, I definitely need stronger springs. I may have the originals from the used disty, but still hoping someone can help with the weight ID and source.

Thanks again

Mike
They’ve got 10 degrees static riming in it. It’s a little confusing, but you’ll see that it does all work out.

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Old 02-06-2023, 10:57 PM
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Originally Posted by Shiny View Post
I want to try and put my points distributor (112008) close to original timing.
Why? The OEM timing was nowhere near what the engine really wanted.

The OEM timing is compromised so that a bad tank of gas combined with carboned-up chambers from Grandma driving and lack of maintenance wouldn't pop the engine.

You're almost certainly more maintenance-intensive that run-of-the-mill drivers from fifty years ago.

Give that engine the timing it wants, instead of the timing GM cursed it with.

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Old 02-06-2023, 11:08 PM
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https://forums.maxperformanceinc.com...d.php?t=864171

Just sayin’.

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Old 02-06-2023, 11:39 PM
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Don’t sweat that chart. Give it as much timing as it will take up to 36°, without pinging, hook up your vacuum advance and go. If it’s at 10° or even 15-20° at idle the only adverse effect would be improved idle cooling. If you have heavy weights on the distributor and the distributor is good, not loose on it bushings and wobbling, and the timing is still erratic at idle, it may be a well worn cam gear. Old worn distributor drive gears will cut a cam and the slop is visible with a timing light. A new gear on the bottom of that rebuilt distributor would take up most of the slop. And, the slop left usually won’t be noticed behind the wheel. Most all Pontiac distributor weights and center plate combos come in at 24°-25° leaving you at 10°-11° at idle. If you use Chevy weights run them upside down to be correct. Don’t sweat it if it’s a little higher at idle. You want to be correct “all in”. It won’t hurt anything at all. What hurts more than anything, is sitting motionless.


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Old 02-07-2023, 12:25 AM
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Originally Posted by promptcritical View Post
They’ve got 10 degrees static riming in it. It’s a little confusing, but you’ll see that it does all work out.
Ahhh!!!

Got it, thank you.

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Old 02-07-2023, 12:27 AM
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LOL

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Old 02-07-2023, 01:17 AM
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Originally Posted by Schurkey View Post
Why? The OEM timing was nowhere near what the engine really wanted.

The OEM timing is compromised so that a bad tank of gas combined with carboned-up chambers from Grandma driving and lack of maintenance wouldn't pop the engine.

You're almost certainly more maintenance-intensive that run-of-the-mill drivers from fifty years ago.

Give that engine the timing it wants, instead of the timing GM cursed it with.
Quote:
Originally Posted by TxSportCoupe View Post
Don’t sweat that chart. Give it as much timing as it will take up to 36°, without pinging, hook up your vacuum advance and go. If it’s at 10° or even 15-20° at idle the only adverse effect would be improved idle cooling. If you have heavy weights on the distributor and the distributor is good, not loose on it bushings and wobbling, and the timing is still erratic at idle, it may be a well worn cam gear. Old worn distributor drive gears will cut a cam and the slop is visible with a timing light. A new gear on the bottom of that rebuilt distributor would take up most of the slop. And, the slop left usually won’t be noticed behind the wheel. Most all Pontiac distributor weights and center plate combos come in at 24°-25° leaving you at 10°-11° at idle. If you use Chevy weights run them upside down to be correct. Don’t sweat it if it’s a little higher at idle. You want to be correct “all in”. It won’t hurt anything at all. What hurts more than anything, is sitting motionless.
Thanks both.

Good info on the worn gear. I'll check it.

My impression was some aftermarket springs and weights could cause erratic idle timing by allowing mechanical advance to cut in and out, or allow the weights to "rattle" right at idle rpm. Is this inaccurate?

As to the overall curve, I set it up for 31 to 34 total mechanical (base + advance) but I want to remove the springs and weights as a possible contributor to the idle issues I had when I last had the engine running. My troubles were likely more about the carb but I do remember the timing jumping around when fighting to get the carb to run on its idle circuit.

I can install stronger aftermarket springs as a starting point to reduce the risk of erratic idle timing being a factor.

I just think it would be safer to start with stock springs and weights so still hoping for guidance and a source.

Mike

  #12  
Old 02-07-2023, 11:19 AM
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This thread reminds me, I cant tell you how many project cars I've bought where the previous owner couldn't get it to run right. Putting a timing light on them showed timing jumping around like crazy. They all had the vac advance hooked into manifold vacuum, so the distributor was sitting there just swinging the timing around like crazy at idle. Switched it to ported, and the timing was smooth and steady.

Not saying that's your issue. Just reminded me on how something so simple can often be overlooked.

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Old 02-07-2023, 12:02 PM
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Originally Posted by 72projectbird View Post
This thread reminds me, I cant tell you how many project cars I've bought where the previous owner couldn't get it to run right. Putting a timing light on them showed timing jumping around like crazy. They all had the vac advance hooked into manifold vacuum, so the distributor was sitting there just swinging the timing around like crazy at idle. Switched it to ported, and the timing was smooth and steady.

Not saying that's your issue. Just reminded me on how something so simple can often be overlooked.
Thanks for this reminder. I'm capable of almost any blunder and will check again.

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Old 02-07-2023, 12:19 PM
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Unlike HEI, GM only used a handful of different weights for points distributors. The center cam (which is welded to the main shaft) and springs controlled the rate. The limiting pin and its corresponding slot in the breaker cam assembly largely limited total timing.

The most effective solution is to get it on a distributor machine and accurately verify the advance curve at idle and throughout the entire RPM range. Then you can eliminate the distributor as a variable.

If you happen to be anywhere near Omaha in the future, you're welcome to stop by and we'll throw it on my machine.

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Old 02-07-2023, 12:20 PM
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Quote:
Originally Posted by 72projectbird View Post
This thread reminds me, I cant tell you how many project cars I've bought where the previous owner couldn't get it to run right. Putting a timing light on them showed timing jumping around like crazy. They all had the vac advance hooked into manifold vacuum, so the distributor was sitting there just swinging the timing around like crazy at idle. Switched it to ported, and the timing was smooth and steady.

Not saying that's your issue. Just reminded me on how something so simple can often be overlooked.
I run my vacuum advance off of full manifold vacuum. It's very steady at idle. I was under the impression that most people connect to full manifold vacuum.

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Old 02-07-2023, 12:29 PM
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post a picture if your weights it will be easy to tell if you have aftermarket ones or not

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Old 02-07-2023, 12:45 PM
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Wasn't 68 like the first year of ported vacuum?

It's what I use and again ... perfectly steady vacuum signal and timing.

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Old 02-07-2023, 01:03 PM
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https://forums.maxperformanceinc.com...r.php?u=143447

FWIW, this is a member on the board that does distributor service, he's located in Memphis TN. Many people on the board have been happy sending their distributors to him to have them curved, and repaired.

I'm certain he has parts from old distributors that he could sell you also, along with springs and weights. I've spoken to him on the phone, and he's a great Pontiac guy.

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Old 02-07-2023, 01:26 PM
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Quote:
Originally Posted by Rocky Rotella View Post
Unlike HEI, GM only used a handful of different weights for points distributors. The center cam (which is welded to the main shaft) and springs controlled the rate. The limiting pin and its corresponding slot in the breaker cam assembly largely limited total timing.

The most effective solution is to get it on a distributor machine and accurately verify the advance curve at idle and throughout the entire RPM range. Then you can eliminate the distributor as a variable.

If you happen to be anywhere near Omaha in the future, you're welcome to stop by and we'll throw it on my machine.
Thanks for the info and generous offer.

Quote:
Originally Posted by wbnapier View Post
I run my vacuum advance off of full manifold vacuum. It's very steady at idle. I was under the impression that most people connect to full manifold vacuum.
Thanks

Quote:
Originally Posted by Formulas View Post
post a picture if your weights it will be easy to tell if you have aftermarket ones or not
I'll try to do that later today.. It's still in the car and haven't looked at it for a few years but it's "on my list" before I try again.

Quote:
Originally Posted by dataway View Post
Wasn't 68 like the first year of ported vacuum?

It's what I use and again ... perfectly steady vacuum signal and timing.
Thanks


The comment about ported vs manifold vacuum makes me wonder if the erratic idle timing could all be about my carb and my distributor is fine. The issue was "nozzle drip" and flooding in the past. The carb was never set up and when I tried, I could not get it to idle without cracking the primary blades. Perhaps this caused the vac advance to cause the erratic timing....??

Thanks to you guys, it now makes sense to compare idle timing with and without the vac advance. Doh!!


The distributor is only one "unknown"... context is a self-induced mess. You can get a feel for the bigger picture here:
http://forums.maxperformanceinc.com/...d.php?t=861753

I've been through the carb again with guidance from Cliff and Kenth, but it's still a big unknown as it is a "Frankencarb" (thread here). It appears "sound" but definitely unproven and still risky. I'm trying to learn, though...

The biggest mess was rust in the tank. I am just doing what I can to address "known caca" before trying to get the car running. I installed a new gas tank and fuel pump, a new balancer, and am currently installing a new radiator. The distributor is hopefully last on the list.

Hope is a strategy..

Mike

  #20  
Old 02-07-2023, 02:22 PM
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Causes for erratic timing at idle speed is most often due to too weak centrifugal timing springs and/or a vacuum advance connected to manifold with a too weak vacuum signal to fully employ the vacuum advance unit. Move to ported source.

Set the timing at idle speed with the original springs removed from the centrifual advance.
Note: Look for/mount a 1/4" bushing on centrifugal stop pin, need to be there.
Use a dial-back timing light, set 30° for 3.25" mains engines and 32° for 3.00" mains engines.
Mount the original springs and check for initial timing, which usually ends up at 9°-12°.
If you think your engine needs a faster "all in" curve, replace original springs for weaker springs, but not TOO weak. Look for steady timing mark at idle speed.
In any case, you will never exceed the total timing you sat with the springs removed.

Now it´s time to tune the carburetor.

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