_________________
Ross Rither
1964 Dart, 170
225, super six.

Didn't see a spec in my manual. I've asked this question in the past and now that I have played with a few distributors I agree with the answer.

None, or as close as possible to none. You don't want any slop. I don't know how much is considered excessive, but you want to be as tight as possible without binding. I'd say that 1/8 inch excessive. Even 1/16 inch is still enough to add another washer, so make it as close as you can.

The last remanufactured one that I got had just a little binding and I took it back apart and filed down the nylon gear ever so slightly.

_________________
1980 Aspen 225 super six

You are correct in that you want as little play as possible...but...remember that you are setting the gear mesh and backlash when you drill that hole.

You could drill the dole for zero endplay, but when you slide distributor into the engine you get too much backlash and little gear mesh...which risks a broken gear.

If you stack a bunch of washers in between distributor housing and gear and have little endplay, then when you tighten the distributor into the block you could smash the gear with less than zero backlash.

Somewhere in between is the exact right amout...

Unfortunatly, Chrysler distributors are not the easiest to solve this problem.

What I do...is put a few extra washer shims on the distributor shaft then drill for no endply. Then put distributo in black and lightly feel the backlask...if none, then shift washer from bottom of distributor to inside distributor at top of housing, thereby moving gear closer to body, but retaining no endply.

But you have to keep taking the distributor apart to get it right.

Karl

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

NAPA Echlin DG-404, iron distributor gear for the slant-6, predrilled. I don't know how accurately, but Echlin's stuff (except their distributor caps) are pretty good, in general.

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

Thanks,
I am going in. It sounds like I'll get good at good at tearing this thing apart

_________________
Ross Rither
1964 Dart, 170
225, super six.

What planet are you from? There is no adjustment of gear mesh and backlash. That is determined by the machining of the block at the factory. Shifting thrust washers around also will NOT change gear mesh or backlash.

Uh...yeah there is, and yeah it will. The position of the distributor shaft relative to the camshaft is a function of distributor and block machining, but the mesh between the cam worm and the distributor pinion is a function of where the distributor pinion is on the distributor shaft.

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

When the camshaft bore is machined in the block, the location of the cam gear side of the distributor interface is set.

Then, the block is machined and the distributor housing psition is set.

Now if your distributor gear is predrilled, then with no shims at all, your gear mesh to the cam gear will be whatever it happens to be...it could be loose, or tight, or maybe even perfect, with just .005" backlash in the teeth, and no endplay in the distributor shaft.

But what if it was loose, with .093"(3/32"), and the gear sits so high that you have little tooth contact, little strength, and possibly break a gear down the road aways...

You couldn't fix this without redrilling the gear, because my example specified no shims and no endplay. Most gears are drilled so that there is excessive endplay in the distributor, and the housings are machined on the short side of tolerance, this makes sure that no factory distributor would be assembled without sufficient endplay and clearance to keep from having zero to <zero backlash in the cam/distributor gear interface.

So typically the factory includes a shim for two reasons, possibly a fixture was used during the distributor gear drilling proccess, and they shimmed them in a jig and drilled, or maybe, they always use one just as a thrust washer because each shaft and gear is drilled the same in a fixture of thier own...I don't know but have seen many different distributor designs in my 20 years as a distributor rebuilder.

But one of the issues is that the distributor gear has drive thrust applied by the cam during accel/deccel of the engine, this pulls the distributor shaft up and down, putting large, changing stress on the distributor cap carbon, and shifting the position of the rotor tip to the cap terminals...possibly promoting various amounts of timing fluxuations, shaft wear, advance weight bushing wear, and maybe even encouraging spark scatter. Its bad enough the cam is flexing, and has thrust back and forth, and the timing chain is slapping around and changing the timing and putting undo side loads on the plastic distributor gear...

Well, because of this, when I build an engine, an integral part of the proccess is to limit the cam thrust, put the distributor in the block while I have access, and measure the backlash, and then set the position of the gear by changing the location of my shims from above the housing to below or whatever it takes.

On engines like my Pontiacs that have a distributor driven oil pump drive shaft, I also have to pay attention to the drive shaft endplay so it doesn't drive the oil pump gears into the bottom of the oil pump housing and destroy the engine.

MSD had a run of Pontiac billit distributors that were machined a bit to long and did just that to many customers about two years ago. And if you just shim the gear down a bunch, or drill your bronze roller cam distributor gear in the wrong place and shim the diff...you very much risk this...but also, on engines like that you have the extra load of pumping oil to worry about for wear and tear in the system.

If I have missed something here in the design of the /6 distributor...even though I have one sitting in front of me right now, or how it is placed in the block and gear mesh obtained...then I am sorry...

Gearhead

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

Wow! that’s a lot of info. Really had to think today. Never thought about the backlash, was stuck on the excessive (.098) thrust on the distributor. I looked at the old gear, had very little contact at the edge of the teeth on the driven side, and a groove type wear pattern on the cost side, like it was binding. I installed the unit with the old gear still on it, and the top plate and mechanical advance out, there was no perceivable play (backlash) when I moved (rotated) the shaft by hand. Heavy grease confirmed the funky contact pattern. I can now see (I think I do anyway) how the gear location on the shaft would effect the contact / backlash, moving it up or down would change how it meshes on the circumference of the cam gear.
Anyway, I used the old gear, drilled for two washers, and then one washer. The one washer, and about .006 thrust at the gear, showed good contact centered on the gear, and some side to side rotation at the mechanical plate. The two washers seemed too tight. Final thrust with new gear .008
This now explains my engine eating rotors, burning at the carbon contacting springlike thing, it was in fact the thrust bearing point.
I have installed this unit, with stock ‘64 curve (11 mech, 6 vac, 8 initial) and hope to fire the new engine tomorrow.
I have a unit with a 9 deg mechanical, and adjustable 8.5 vacc, and assorted springs. I plan on using later, allowing my initial to be at 12 deg. That’s later, so am I.
Later.
Ross. I love this place!

_________________
Ross Rither
1964 Dart, 170
225, super six.

Wow:

You took what I had to say right to heart!!! Glad to be of some help...its the little details that make one car with the same basic parts...more reliable, easier to work on, more efficient, quicker...etc.

One thing I always try to do...is never take anything for granted, don't trust what anyone says until you've verified it yourself, and anytime you run into a hassle, like wirng that is too short, or a hose that blocks valve cover removal, or a sharp edge that cuts my hand when I try to adjust a belt, or a coil thats hard to reach...or whatever...fix it!

Over the years your car becomes a dream to work on...and rarely breaks in the first place...

Karl

_________________
64 GTO...10.80's@122 on street radials
Destroked 455, Qjet, stock ign, 2400 stall

64 Valiant
Old 225, 4spd, 2.92-8.75, 2bbl, headers
dual 2.25"

I know this is an old post but the info is great.

I wanted to add that if the slant six distributor is not assembled correctly It is very hard to get the distributor in the correct position so the engine is correctly timed.

Pictor of the proper alinement, between the gear and the upper plate can be found on this other site.

http://www.forabodiesonly.com/mopar/sho ... ost1106874[/img]

I cant seem to be able to post a picture without having it on a picture host web site.
[/url]