Distributor question

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volaredon

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I have 1 at the moment, am getting a 2nd tomorrow.
(Steel distributor gear) Long discontinued Napa part from a /6 racer buddy.
Any reason "not" to run it?
I have a NOS (not rebuilt!) Distributor in my engine right now. Has its original nylon gear on it. Only because it is NOS. And I've only got ~250 miles on that distributor since I got it.

My spare distributor has my steel gear on it, same distributor number as my NOS one, only with lighter springs in it that I put in, and a new vac advance pod. It's the 78ish one that all the non California super 6 engines got.
My buddy that I got the first one from, found a 2nd steel gear in his stash, that I want to put onto my NOS distributor when I pull the nos one to put my recurved one in to "experiment" with.
When I had my 79 truck I had trouble keeping nylon gears on its distributor.
Any reason not to run the steel distributor gear?
 
The real question is "what is the reason to run it"? Plastic dist gears do not have any problems that I am aware of. Old/ brittle gears yes, but not fresh gears. This is my way of thinking. There is very little "load" on the dist gear when using an electronic dist (even with points very little). But lets say you have a problem with the distributor (cap/rotor interference for example) cap/rotor breaks, jams the dist, and messes up the shaft or in the extreme the cam gear. With the plastic gear the only damage would be the gear itself.
I do have a couple of metal dist gears that I have had for many years, and never had a reason to use them. I think they are a "fix" looking for a problem that doesn't exist.
 
I wouldn't run it. It's not an upgrade. Just as Charlie said.
 
I would only use a plastic part inside an engine if that was all that was available.....
 
volaredon said:
I have 1 at the moment, am getting a 2nd tomorrow.
(Steel distributor gear) Long discontinued Napa part from a /6 racer buddy.
Any reason "not" to run it?
I have a NOS (not rebuilt!) Distributor in my engine right now. Has its original nylon gear on it. Only because it is NOS. And I've only got ~250 miles on that distributor since I got it.

My spare distributor has my steel gear on it, same distributor number as my NOS one, only with lighter springs in it that I put in, and a new vac advance pod. It's the 78ish one that all the non California super 6 engines got.
My buddy that I got the first one from, found a 2nd steel gear in his stash, that I want to put onto my NOS distributor when I pull the nos one to put my recurved one in to "experiment" with.
When I had my 79 truck I had trouble keeping nylon gears on its distributor.
Any reason not to run the steel distributor gear?
Click to expand...
You have to be aware that there are stock gears & replacement gears, replacement gears have the roll-pin hole higher, & are intended to have a new hole drilled through the shaft above & 90° to the original one.
Examine & measure the gear carefully before doing/deciding anything, the replacement requires a specific procedure to index & position it.
 
Bewy said:
I would only use a plastic part inside an engine if that was all that was available.....
Click to expand...
It would depend on the part. If you would have a metal distributer/cam gear compatibility issue (remember there have been issues with the oil pump/cam gear) would you rather have metal pieces/fillings inside the engine or plastic? Also it is easier to just change the plastic dist gear, than the metal dist gear and the cam, due to possible cam gear damage from the metal dist gear
 
I have rebuilt hundreds of them the nylon gear seriously holds up The hard to find metal ones are really used in HP slants. I have them NOS if needed.
 
Ok... Related questions.
What would the "shelf life" of old NOS plastic ones be? Would the plastic either get more brittle or somehow "soften up" from having sat on a shelf somewhere? Whether factory NOS or aftermarket NOS?
As we all know these gears aren't as readily available anymore, (there used to be a couple of them on every "lazy Susan" style parts store display back in the day/ but some parts stores can't seem to even order one anymore)
Does anyone even make them anymore?
We all know how long it's been since these engines were common on the roads. Not the same as "current models" but "commonly seen running around".

In my case I'm running an original '74 cam that I sent in to Oregon cams to be reground. Not a more recent aftermarket cam that seemed more likely to have cam gear deterioration issues.

That said/ that 79 truck I had, I replaced the engine back around 1988 because the cam gear shredded. And i'd had that truck a couple of years by then and I knew the guy I got it from, I know that he was never inside that engine. It was pretty low mile when he got it, it started eating distributor gears a bit before the cam gear shredded. If you'd have cut the cam off either side of the distributor and oil pump drive gear it would have looked like a "D" cross section, with all teeth shredded off one side, far from round.
At the end for that engine I sat in a farm field access, on the side of the road and replaced that plastic gear 3x before I realized what was wrong.
In that 3rd time of replacement the that afternoon when I went to drop the distributor back in the "flat side" of the gear was facing up where I could see it.... As far as I know that was the original cam to that motor.
 
On the prospect of a distributor "jamming" I guess it's possible but I've never seen it happen. Not saying that means it won't/can't happen at all .. just seems quite unlikely
 
volaredon said:
On the prospect of a distributor "jamming" I guess it's possible but I've never seen it happen. Not saying that means it won't/can't happen at all .. just seems quite unlikely
Click to expand...
Or maybe the shaft is slightly bent, running out of true.
 
The shelf life of a plastic part is not relevant. When it breaks......because it is plastic & weak....it breaks.
Post #7 claims the metal gear is used in HP engines. That tells you they are a stronger...& compatible [ post #6 ].
To me, the choice is a no brainer.......
 
well I now have 2 metal gears and 2 /6 distributors.....
 
Never in 20 years have i had a plastic one break.
but i've always used a new one.
ever since i was told to get that junk out of there (it had a brass one when i purchased it)

you might use a steel gear with a roller cam i can never remember the appropriate material for that kind of cam material but gears and pushrods and drives seem to be updated when a roller cam is used

you could use the brass gear with a standard cam they do tend to knife edge the teeth rather quickly and make your oil sparkle. its harder but in materials terms not as tough.
use in a motor that gets stripped and checked regularly. They won't break but they are a sacrificial part that wears in a way that the nylon one doesn't seem to.

the nylon copes well with a slight mismatch of pitch between your aftermarket cam and gear
the metal ones do not cope as well

the main reason for nylon was to protect the bushes in the dizzy from harmonic vibration in the cam.

steel shaft in olite "like" bushings don't like repetitive shock loads and a long cam with harmonic vibration would provide just that

less so on a slant 6 than a hemi 6, due to the thickness of the cam stock between the lobes being greater on the slant, and the drive is at one end, but it is a six. i.e quite a long cam

Just my view but upgrades are either better or necessary changes.
i have not done anything that has made it necessary to change to steel or iron gear.
and a yellow metal gear seems to have drawbacks.

Dave
 
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Ok thanks .. I can still put them at the back of a drawer in the toolbox at this point....
 
well i have to import everything and id rather import a dizzy gear than a whole new cam and lifters so i'm bound to be biased :)

and i have a motor with the distributor down below no.5, which is a long way from the point of drive, and some would say at the wrong end of a long and bendy cam

slant dizzy is up front near the point of drive at a similar position but opposite end so, not so much of a problem

basically I have more reason to worry

hence my bias :)

Dave
 
Charrlie_S said:
Either gear will work. I just stated my opinion, and my reasoning. Engine owner needs to make their own decision.
Click to expand...
Wasn't looking to pick fights or anything, though I really wanted to know what others thought, I didn't think I'd be the only one...
Sometimes I ask what I do for " looking at an issue from devil's advocate" point of view.
But on my used and "self rebuilt" distributor the old gear just kind of crumbled when I went to knock the pin out of it and I have to replace it with "something".
I had the 1st steel gear already and I figured instead of ordering something that these days will probably either come from China, or has sat in a shelf for 30 years, I thought I'd just use what I already have. And then Zilla posted that 2nd one on the other site (he's who I got my 1st one from, too) I just figured I'd put it out there.
I honestly thought they got discontinued because they don't make a /6 anymore and reverting to "only the plastic version" was a way of parts makers going cheap. As is so common now a days.
Or did they discontinue the steel one because of an actual problem with them?
I see that the Aussies also have a 3rd choice (bronze I believe) but since the only way I can get that one is by paying more to ship it than the thing even costs to buy I wasn't even considering that choice.
My current project is pretty much for a daily driver in a truck, not a race situation. That might change some people's answer (or not) might occasionally do a little bit of (light) towing of a garden tractor or 2.

Next question (it was asked also in a previous reply to this thread) is there a shelf life to the plastic/nylon ones?
I realize that even though "old" a new one that's lived on a shelf for umpteen years hasn't been subject to the heat/cool cycles like one that's been running an engine for years.
 
i have used new nylon when i was doing something planned

i have used any old dizzy with anu old gear nylon gear when i have been pressed into it due to circumstance ie sending off my good (unique to this motor) dizzys for recondition and recurve i ran on aold points one as found for about a year

still not had a problem

the only place i have heard of a problem with nylon gears is in the sales pitch for a brass gear

never say never you might get a bad one or a sub standard one and i might just have been lucky

they will eventually get pickled in oil nasty old oil, they look like they are old and stained and they get a little bit more brittle BUT i'm talking 50 years old...... that's good going for a car and motor that the manufacturer expected to be made into bean cans somewhere between year 7 and year 10

on mine it is for the vibration in the cam. there is a harmonic nodal point in the middle. Dizzy is sited in a gap between it a and the second nodal point, below cylinder 5 , hence my dizzy at cylinder 5 and yours nominally at cylinder 2. not in the middle...! they thought about where to put it

on yours possibly less of a vibration worry, less distance to flex between the cam drive and your dizzy gear. but chrysler in general thought about their engineering in a way that some of the others did not

and we are talking small torsional twists in the cam, putting vibration into the dizzy shaft, like its shivering, as the valve springs alternately load up and unload and the clover leave impeller in you oil pump is in the "entrance closed"- "exit closed" millisecond between each "pump"

on high output hemi 6s some run nylon blocks in the cam area to act as support or damper of cam vibration and flex. you would not be likely to be running your slant at 7000 rpm so would never need the kinda spring that causes that much flex.

Dave
 
volaredon said:
Wasn't looking to pick fights or anything, though I really wanted to know what others thought, I didn't think I'd be the only one...
Sometimes I ask what I do for " looking at an issue from devil's advocate" point of view.
But on my used and "self rebuilt" distributor the old gear just kind of crumbled when I went to knock the pin out of it and I have to replace it with "something".
I had the 1st steel gear already and I figured instead of ordering something that these days will probably either come from China, or has sat in a shelf for 30 years, I thought I'd just use what I already have. And then Zilla posted that 2nd one on the other site (he's who I got my 1st one from, too) I just figured I'd put it out there.
I honestly thought they got discontinued because they don't make a /6 anymore and reverting to "only the plastic version" was a way of parts makers going cheap. As is so common now a days.
Or did they discontinue the steel one because of an actual problem with them?
I see that the Aussies also have a 3rd choice (bronze I believe) but since the only way I can get that one is by paying more to ship it than the thing even costs to buy I wasn't even considering that choice.
My current project is pretty much for a daily driver in a truck, not a race situation. That might change some people's answer (or not) might occasionally do a little bit of (light) towing of a garden tractor or 2.

Next question (it was asked also in a previous reply to this thread) is there a shelf life to the plastic/nylon ones?
I realize that even though "old" a new one that's lived on a shelf for umpteen years hasn't been subject to the heat/cool cycles like one that's been running an engine for years.
Click to expand...
1st, if it's packaged, & not sitting in the sun...it should fly fine.
2nd, You really need to heed My above post, and here's why...
20240130_224847.jpg


20240130_224941.jpg
 
I have seen a nylon distributor gear break once.

When I dropped a screw into the distributor while adjusting the points and forgot about it. Probably would have been even uglier if something else had been the weakest link. Outside of blatant abuse, the gears hold up pretty well. If I were really worried about the last bit of timing accuracy, I'd make an even bigger jump and go crank fired.
 
They hold up well only had one core with a chipped tooth. If they are kind of yellowish pass on them they were stored in heat.
 
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