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Any idea what causes this one side of the gear wear..? Pulled my distributor as I am thinking of putting a pertonix in it. it had a few shims in it.pertronix tells you to shim so no more than .010 to .060 clearance up or down so magnet ring does not rub the component.. Anyway changed gear, haven’t shimmed or installed yet with the pertronix because I need to know what caused this gear wear on one side? Any ideas?
What cam core are you running? I'm *assuming* that's wear from a hard gear on the cam, so you need either a melonized gear on the distributor that's hard enough to deal with it, or a bronze gear that you check and replace regularly.
Shimming is a chevy thing. Chevy spins the distributor the other way around, which pushes the shaft upwards. So shims are (sometimes) needed to keep the shaft from moving too much. An olds actually pulls the shaft downward, so shims between the gear and the housing will just be along for the ride.
Just putting in a replacement gear will do the same thing.
Oh, the other option is that the squirter hole in the plug in the back of the oil galley - facing the distributor gear - is either plugged, or someone put in a plug without a squirter hole (happens *a lot*). Run the oil pump with a drill and a 5/16 hex extension and you should see a nice stream of oil down there spraying right by your extension rod. If not, then there's a problem. Check around on here - at least one guy managed to R&R that plug with the engine assembled and in the car. It's possible, just super agravating.
Placing shims in the Olds distributor can cause the gear to bottom out against the machined pad down inside the block before the locating ring on the distributor housing is fully seated against the top of the block. This will cause binding of the gear against that pad inside the block possibly leading to accelerated wear. If you desire to shim the distributor gear in an Olds for whatever the reason, first mount the distributor in the block clamped in place before measuring the initial amount of up/down clearance. Verify again after shimming to ensure that you have an adequate amount of clearance. As "oddballl" mentioned above, "shimming is a chevy thing"!
Any idea what causes this one side of the gear wear..?
This gear also drives the oil pump. If you use oil with high cold viscosity (higher first number on the grade) you put a very high load on the gear, which can cause that wear. for example, 20W oil at 50°F puts almost four times the load on the distributor gear as 5W oil does.
If you have been using a a high first-number oil, start using an oil with first number of 5W or 0W. Second number of 40 or 50 will ensure your oil stays thick enough for good protection when warm.
Placing shims in the Olds distributor can cause the gear to bottom out against the machined pad down inside the block before the locating ring on the distributor housing is fully seated against the top of the block. This will cause binding of the gear against that pad inside the block possibly leading to accelerated wear.
^^^THIS. And once the distributor gear is bottomed out, friction goes up dramatically, which increases wear on the gear since it requires more force to turn it.
Also, has the engine been rebuilt? Did the correct plug with a weep hole get installed in the end of the oil gallery to lube the distributor gear?
^^^THIS. And once the distributor gear is bottomed out, friction goes up dramatically, which increases wear on the gear since it requires more force to turn it.
Also, has the engine been rebuilt? Did the correct plug with a weep hole get installed in the end of the oil gallery to lube the distributor gear?
The engine was rebuilt by the second owner, they must have shimmed the distributor back then,( you can see three shims, basically no up/ down movement) yes it does have a crane flat tappet cam, w30 cam was pulled out of it at that time. Looking down the distributor hole the cam gear looks fine, it is oiling fine as well. As far as shims moving forward pertronix says to shim basically so the black box isn’t rubbing the magnet ring when the distributor is pulled down with the engine running as we know olds engines pull the gear down. So I will need the shim to keep that 10,000 clearance between the magnetic ring in the box as the instructions say. I guess the question is do I need to put a hardened gear on or will another factory distributor gear work OK?
Do not shim between the gear and distributor body. That's your problem. You are most likely pinching the gear. Take the shims out and drop it in the motor then check your gap. Shims in that location will pull the shaft down in relationship to the body.
Is there any chance that the weep hole that sprays oil on the gears could be plugged?
It appears to be oiling just fine, I think the extra-shims the 2nd owner had put in there is-the culprit ..is has virtually no up or down movement. I guess I will put a hardened gear in there with just enough shim to keep the magnetic ring from rubbing the black box. Weird thing is I didn’t think a flat tappet cam would need a hardened gear, thought that was roller cam territory. Any suggestions on WHAT gear to use? I certainly don’t want a gear thats harder than the cam gear..
Do you have a specific question on the recommendations already made?
If your cam gear is still perfect, it would be prudent to try a gear with different characteristics than the factory gear had. The Melonized and composite gears have better better wear characteristics and the Ampco 45 is sacrificial and will never damage the cam gear.
Last edited by VC455; April 6th, 2022 at 01:40 PM.
Do you have a specific question on the recommendations already made?
If your cam gear is still perfect, it would be prudent to try a gear with different characteristics than the factory gear had. The Melonized and composite gears have better better wear characteristics and the Ampco 45 is sacrificial and will never damage the cam gear.
My specific question was two fold and yes I believe answered..I am leaning toward the chewed gear was because somebody stacked shims on the distributor leaving basically no clearance causing the issue in the pics. The other question on what gear to use moving forth you just answered..thank you. Much appreciated
Before dropping the distributor back in, spin the oil pump with a drill. I THINK the oil pump driveshaft is 5/16, a 6 point socket fits perfectly. Just tape the socket to the extension, it would REALLY suck to drop a socket into the oil pan. Make sure someone didn’t install the wrong oil galley plug, or that the proper plug isn’t restricted with crud.
A high volume oil pump or "tight" oil pump can also cause a worn distributor gear.
Andy, this is what I was referring to in post 6. The distributor gear wear from the pump load occurs when the oil is cold. A 0W oil minimizes the cold wear on the gear.
Andy, this is what I was referring to in post 6. The distributor gear wear from the pump load occurs when the oil is cold. A 0W oil minimizes the cold wear on the gear.
Gary
I have been using vrt 20-50 high zinc content, in Florida.. I will change to a lower numerical oil, like 5/15 or something, 10-30..thanks Gary…
[QUOTE=67OAI;1418475As "oddballl" mentioned above, "shimming is a chevy thing"![/QUOTE]
For you guys that are making this statement you have obviously never done a Pertronix conversion. You have to shim the shaft to get the correct clearance for the magnets in the pickup assembly. I just did one on a 425 a month or so ago. It does not affect or cause the problems you see here.
To the original poster ..... What camshaft are you using ? Did you replace the distributor gear ? Regular or high pressure oil pump ? The wear you see is from the gear driving the oil pump. If you did not replace the gear you are taking a big chance on a new camshaft. Might already be too late, you need to look very closely at the camshaft gear.
I have been using the gears that Chris Straub sells but any good Melonite gear should be ok. I bought one gear from Summit a couple of years ago and it was a very loose fit on the shaft. You get what you pay for. https://distributorgears.com/
For you guys that are making this statement you have obviously never done a Pertronix conversion. You have to shim the shaft to get the correct clearance for the magnets in the pickup assembly. I just did one on a 425 a month or so ago. It does not affect or cause the problems you see here.
To the original poster ..... What camshaft are you using ? Did you replace the distributor gear ? Regular or high pressure oil pump ? The wear you see is from the gear driving the oil pump. If you did not replace the gear you are taking a big chance on a new camshaft. Might already be too late, you need to look very closely at the camshaft gear.
I have been using the gears that Chris Straub sells but any good Melonite gear should be ok. I bought one gear from Summit a couple of years ago and it was a very loose fit on the shaft. You get what you pay for. https://distributorgears.com/
I wouldn't use a Pertronix if gave to me. There's a much better ignition module made by M&H Electric,American Auto Wire etc. that's a plug in play. They use one wire as per OEM points and you still use the stock resistor wire,no 12 volts needed. All you guys using Pertronix with no issues good for you,don't need to hear about how great they are. Seen too many on the hook. Oh and the modules I'm talking about doesn't need any freaking shimming to clear the pickup.
And that has absolutely nothing to do with this thread or helping solve this problem
Pertronix says to shim the distributor for clearance for the module. The OP has a distributor with a bad gear and was more than likely caused by his distributor being shimmed. Related I would think to this thread..
The wear most certainly was not due to oil viscosity. In addition to the shims causing your issue, are you running a flat tappet cam or roller?
I would agree. When you can spin a oil pump with a cordless 3/8 drive, pumping cold oil, it obviously doesn’t take much power to do it. The little power needed to turn the pump isn’t that much stress.
Im betting the OP has cam/gear compatibility issues, a improper or restricted oil galley plug, or some other oiling issue, or a improperly shimmed distributor.
Ok I am going to back up on this and apologize. The Pertonix kit that I installed for a customer worked out fine without taking all of the end play out of the distributor. Looking closer at the picture here it does look like the shims have completely closed up the end play and might possibly be causing the problem ? Its really hard to say without having it in front of me to look at.
Matt said that there isn't much stress to drive the pump ? I am going to respectfully disagree. There is a big difference between driving it directly with a drill and driving it with the cam gear. It takes virtually no power to turn the distributor so I would say that 99% of the wear on the gear comes from the pump.
Andy, Put your distributor in the oven and heat it up to around 180 degrees. Then see if you can spin it easily. If so the shims are "probably" not your problem.
For you guys that are making this statement you have obviously never done a Pertronix conversion. You have to shim the shaft to get the correct clearance for the magnets in the pickup assembly. I just did one on a 425 a month or so ago. It does not affect or cause the problems you see here.
To the original poster ..... What camshaft are you using ? Did you replace the distributor gear ? Regular or high pressure oil pump ? The wear you see is from the gear driving the oil pump. If you did not replace the gear you are taking a big chance on a new camshaft. Might already be too late, you need to look very closely at the camshaft gear.
I have been using the gears that Chris Straub sells but any good Melonite gear should be ok. I bought one gear from Summit a couple of years ago and it was a very loose fit on the shaft. You get what you pay for. https://distributorgears.com/
Its a flat tappet cam, I did not do the build, it was built in the mid 80’s. Obviously I plan to replace the gear and shim the distributor for the proper clearance Pertronix ask for. Looking down the distributor hole cam gear looks fine. I found this issue simply because I decided to put a pertronix in it. Whoever rebuilt the engine back then shimmed the distributor to basically have zero up and down play. So I am replacing the gear, setting up the pertronix and going from there. I can periodically check the gear as this car does not get many miles put on it..Most classic cars don’t..On a side note the argument for or against pertronix can go on for months. The m&h unit I had never heard of till talking to Mike after I bought pertronix. The gear was covered in oil when I pulled the distributor so I will assume its getting oil. Not going to pull the engine apart to check the weep hole. I am pulling engine next year sometime to put the factory block back in it. Everything can be double checked then
Ok I am going to back up on this and apologize. The Pertonix kit that I installed for a customer worked out fine without taking all of the end play out of the distributor. Looking closer at the picture here it does look like the shims have completely closed up the end play and might possibly be causing the problem ? Its really hard to say without having it in front of me to look at.
Matt said that there isn't much stress to drive the pump ? I am going to respectfully disagree. There is a big difference between driving it directly with a drill and driving it with the cam gear. It takes virtually no power to turn the distributor so I would say that 99% of the wear on the gear comes from the pump.
Andy, Put your distributor in the oven and heat it up to around 180 degrees. Then see if you can spin it easily. If so the shims are "probably" not your problem.
check out season 6 episode 93 of engine masters. They did a dyno test of the same engine, (440 mopar) but with standard oil pump, high volume, high pressure, and a aftermarket huge Milodon pump. With the exception of the Milodon pump, there was a minimal difference in hp, certainly not enough to account for a distributor gear to last hundreds of thousands of miles with a standard pump and low viscosity oil, verses high column and thick oil destroying the gear quickly.
I won’t disagree that it takes more power to make more pressure, or more power to move more oil, but we are talking about a minimal amount. Seriously, how much hp could a cordless drill possibly make?
It does if you have a Chebby. Since Olds distributors turn in the opposite direction, the loads from the helical gears pull the distributor gear down against the block, not up against the bottom of the distributor as shown in that article.
It does if you have a Chebby. Since Olds distributors turn in the opposite direction, the loads from the helical gears pull the distributor gear down against the block, not up against the bottom of the distributor as shown in that article.
I understand that. I thought the part about installed distributor height and the article in general might be helpful to some.
"GM" adds credibilty to what might need to be done with a Chebby. Every GM distributor rotor except BBC and SBO (not sure about LS) turn counterclockwise. You might find a tip or two, but most of it is nonsense. It does appear to me that all the shimming needed is because of the sheetmetal intake manifold.
It has nothing to do with the direction the distributor turns. It depends on what side of the cam the distributor is on. On a Oldsmobile the distributor is on the drivers side of the cam. The driving gear on the cam pulls the driven gear down. On the Chevy, it's the opposite side, pushing up. The direction the distributor turns depends on the angle the gears are cut on. It can go the opposite direction if the gears are cut that way and it will still be pushed or pulled in the same direction.
Folks i dont know what caused it, I bought a pertronix on a friends advice..pain in the *** so I basically cleaned, re- oiled and set up my original distributor and things are working fine..bottom line is for some reason my 455 does not like, or want 34 degrees total timing..causes problems..why? No idea.. just know at 28 -30 total, 7-8 initial it smooths out and runs, starts fine. I shelved the pertronix as after install, nothing changed.. yes, I found tdc, it ended up being on the 4 BTDC line, not at zero..again,, why..no idea
Folks i dont know what caused it, I bought a pertronix on a friends advice..pain in the *** so I basically cleaned, re- oiled and set up my original distributor and things are working fine..bottom line is for some reason my 455 does not like, or want 34 degrees total timing..causes problems..why? No idea.. just know at 28 -30 total, 7-8 initial it smooths out and runs, starts fine. I shelved the pertronix as after install, nothing changed.. yes, I found tdc, it ended up being on the 4 BTDC line, not at zero..again,, why..no idea
Outer ring on balancer has probably slipped. Not uncommon @ all.
April 6th, 2022, 06:48 AM
