I'm installing a new gear on my 225 distributor. How much should the shaft be able to move up and down.

a few thousandths of an inch. You cannot use the predrilled hole on the new plastic gear, it is in the wrong place.

The Slant-6 distributor is turned by a nylon drive pinion that meshes with a worm gear cut into the middle of the camshaft. Sometimes the drive pinion breaks, and then the distributor stops turning. When that happens, the engine stops running.

A new distributor drive pinion can be bought easily as Dorman № 90450. Over the years there have been metal pinions available from various sources. They're pretty, for sure, and for a time I fell under their spell; metal's gotta be better than plastic, right? Well…no. Think about it for a minute: your distributor has a nylon drive pinion—the kind factory-installed on millions of Slant-6 engines. The distributor locks up for whatever reason. That sucks, but all that happens is the engine stops and you need to repair or replace the distributor.

Okeh, now replace that nylon pinion by a metal one, lock up the distributor, and the damage gets quite a lot more extensive and expensive—starting with shredding the camshaft worm and easily spreading to the nearby oil pump, etc.

The nylon pinion, installed correctly, is much more than adequate.

When you examine the new nylon pinion, you will see that a hole has already been drilled in its shank, and on first glance it will look as if this is meant to accept the roll pin. That is not the case. You must not use the single hole that is drilled in the gear when you purchase it. If you do, you will very likely break stuff and have another distributor failure (= engine quits) in short order.

What you must do is push the top (rotor end) of the distributor mainshaft down towards the drive end of the distributor. While doing this, place the new thrust washer over the drive end of the shaft. Maintain downward pressure on the mainshaft, and fit the new nylon pinion on the drive end of the shaft, with the new pinion's predrilled single hole clocked 90 degrees away from the hole in the distributor mainshaft.

Place a 0.007" to 0.009" feeler gauge or shim between the pinion and thrust washer. Make sure the new pinion is fully seated (all the way down) on the shaft, making good contact with the feeler gauge or shim without leaving any up and down movement in the mainshaft. This controls the distributor mainshaft end play.

Once you've positioned the new pinion correctly, it's time to make the new holes in the pinion. You can use the tip of a hot soldering iron (or a flame-heated darning needle or paperclip) to create a pilot hole. Once you've got the first hole drilled, the second one's a piece of cake; all you have to do is make sure not to side-load the drill bit, which would wallow out the shaft pin hole. The idea is to drill through the pinion such that you create two holes exactly in line with the existing distributor mainshaft cross hole, taking care not to enlarge or ovalise the mainshaft cross hole, as this would allow the pinion roll pin to come loose.

Using an appropriate hammer and punch, drive the roll pin home such that it is even on both ends, does not protrude too much from either side, and engages both sides of the drive pinion.

Now, the factory service manual procedure for replacing the pinion includes a method for making sure the new pinion is clocked the same as the old pinion relative to the distributor shaft, so it will be easy to drop the distributor in and have it close to the original timing range. You don't have to be exact about this, just try to pay some attention to the position of the roll pin hole in the old pinion, relative to the nearest teeth, and try to get it about the same with the new pinion. Odds are you will have to start from scratch on getting the timing right.

That helical distributor drive pinion can bamboozle even those of us who've removed and installed slant-6 distributors countless times. It can seem for all the world like everything's exactly where it's supposed to be, and yet the engine won't start! There are only a limited number of teeth on the pinion, so at times like these, I usually just remove the distributor hold-down bolt, note the position of the rotor, carefully pull the distributor out, very slightly turn the rotor clockwise and push the distributor back down, thus advancing it by one tooth. Snap the cap back on (don't bother with the hold-down bolt, as long as you can see the hold-down bolt hole in the block through the distributor hold-down plate), and crank the engine. If still no start, advance the distributor one more tooth. Repeat this a few times, and sooner or later you will get some activity under the hood. It'll likely start with a change in the starter sound — either the starter will struggle and hitch, or it'll spin faster as the engine "tries" to start, or maybe you'll get a "POOF!" spitback through the carburetor. Carefully keep track of how many steps (teeth) you move through, so if things just keep getting worse and never better you can go back to your starting position and then go one tooth the other way and see how you go from there. Keep moving the distributor a tooth at a time until the engine fires and runs. Once that happens, move it one more tooth in the same direction as the step that made it run, to see if the engine runs better or worse. If better, leave it there. If worse, go back one tooth. Then reinstall the hold-down bolt loosely, set your timing by the normal procedure with a timing light, and tighten down the bolt.

If you can't seem to get the timing adjustment you need because you reach the end of the slotted hole in the distributor hold-down plate before you get where you need to go, remember there is a second bolt under the distributor. It holds the hold-down plate to the distributor body. Use the correct wrench to loosen this bolt with the distributor installed, or remove the distributor and use a regular wrench. Move the plate relative to the distributor to get the additional movement you need to include a range of about 2° BTDC to 12° BTDC within the hold down plate's slot where it attaches to the block. This does not apply if you have the late-model distributor hold-down arrangement that has a round ring on the distributor and a hold-down fork bolted onto the block that bears down on this ring.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

by the way, where can I get a new gear.

Just about any parts store can sell you a new one.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

thanks alot....................matt

Dan,
A question about the nylon gear. You said the pre-drilled hole was in the wrong place. I used one on my distributor without a problem, aside from the gear not having 2 holes, so the pin could go thru the othewr side. I just drilled on through, runs well, although you say there should only be a few thousands play? Mine seems to be able to move up and down a 1/4" or so with the distributor out, but looks like when it's set in place against the cam's drive gear, it really wouldn't have anywhere to go. (I could be very wrong, let me know please, thanks).

I'm curious about the hole in the wrong place as well. What diference does it make? It is a gear, and it seems that the relationship of the teeth to the rotor or the shaft of the distributor is irrelevant. It like saying that your alternator pulley is 90 degrees off in relation to the aternator drive shaft...

You are very wrong on this assumption. Your distributor end play is much too great, which causes problems of its own (timing instability, great likelihood of broken distributor parts or suddenly-hung distributor, etc), but more importantly than that, you are begging for a broken distributor drive pinion or jumped timing. With the pinion hanging off the end of the shaft as you've got it (and only half-secured), it's not meshing completely with the cam worm; only a small portion of each pinion tooth is contacting the cam worm. I think you may not quite have a clear mental picture of how this mesh is supposed to occur, since "when it's set in place against the cam's drive gear, it really wouldn't have anywhere to go" is not correct.

Reed, by now you'll probably have understood that your alternator pulley analogy isn't valid. The problem isn't with the clocking of the hole in the new pinion, it's with the axial position of the hole relative to the ends of the pinion shank.

"No apparent problems running it this way" is great until the engine quits in the middle of traffic or out in the boonies at night in the rain or anytime else. It doesn't take much more effort or time to do the installation correctly...

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Wel, actually, I still think I am right on this. I replaced a busted factory gear with a Napa Nylon gear and the car ran great for over a year like that before I sold it. The distributor gear is simply evenly spaced teeth placed around the diameter of the shaft. It seems like the placement of the teeth is purely arbitrary, especially when you consider that the body of the distributor is designed to rotate independently from the shaft to allow for timing adjustment. As long as the teeth mesh with the cam ,why does the relative placement of the teeth matter?

Dan wrote: "The problem isn't with the clocking of the hole in the new pinion, it's with the axial position of the hole relative to the ends of the pinion shank. "

I will behonest and say I don't understand what you are talking about here, so maybe that is why I am confused. Correct me if I am wrong but the only function the distributor drive gear serves is to turn the distributor shaft. The only way I could see the position of the hole for the role pin being placed incorrectly is if the hole was placed too colse to one edge of the gearm aking the distance between the gear and the camshaft incorrect. In other words, placing the gear either too far away from the cam once the distributor is seated in the block, or placing the gear to close to the cam to when the distributor is bolted down the gear is pressed to tightly against the cam causing premature wear.



Okay, wait, now I get it. You done used tham fancy words agin'!

I think we are saying the same thing. Drilling the hole 90 degrees out would be in order to lessen the possibility of weakening the gear from having the holes too close together. Gotcha. So what is the proper distance from the edge of the gear for the hole to be drilled?

what Dan's getting at isn't about the "pulley being 90 off on the shaft"...it's How far the pulley has been pressed 'on the shaft' so the belt will line up properly (like going from a 40 amp single pulley, then putting a 65 amp double pully special on but using the 'outer belt position'..)...

In this case if the shaft has 1/4" play, the gear working against the cam will cause the shaft to climb or bounce up and down with rpm and could cause a reluctor misalignment (missed timing isn't good), the rotor to contact a post in the cap (ouch...)...or ?

The similar case is Doc's oil pump gears and the need to install the oil pump and check the gear relationship to cam gear...if it's off a bit or if the cam wasn't cut right it'll show up and you can correct it (change cam, press or shim the oil pump gear to the correct position)...or have a bad oiling day.

-D.idiot

DING! You've got it.
Yep! That's it exactly.
This wouldn't happen (pinion shank would hit the bottom of the distributor housing during installation, preventing "too close" installation)
DING! again.

I do not know why they bother drilling a hole in the wrong place, but that's what they do, and it's what they've been doing since 1960 on the replacement pinions. There are lots of 2084653 replacement pinions still available on the market. In each and every box is contained one pinion, one roll pin, one washer and one instruction sheet that says what I've typed above ("Don't use the hole already drilled in the pinion, here's how to drill the pinion, etc."). The same information is in the FSM.
Can't be supplied as a dimension, due to production tolerances in nylon castings. You remove the old pinion, seat the shaft fully downward (maximum exposed shaft length at the bottom of the housing), place the oil control washer on the shaft, then the pinion, then rotate the pinion so its one hole is 90° off from the holes in the shaft, then drill the pinion to match the shaft hole (being careful to pick the correct-size bit so that you do not enlarge the shaft hole), then you install the pin so it's even on both sides, then you're done.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Are the distributor gears drilled correctly for any vehicle?

Just wondering if it's a common mopar part used in the V8's

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

No, the pinion is slant-6 only.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Dan - Thanks, I also finally got it about the gear and the incorrect hole. I just put the old one back and realized the problem, (the old one was fine). One of the threads here had said if your timing mark was wandering, it may be a worn dist. gear. (I replaced the timing chain/gear set, and that helped a lot), but it still moves around a little, I'll ignore for now.

Excessive side play in the distributor shaft, due to a worn bushing, can cause unsteady dwell in a points distributor and that can affect timing as well. It shouldn't be as much of an issue with electronic ignition.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.