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Distributor Drive End Float

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KVH

KVH

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I better ask for help again:

The manual gives a clear way to check end float using a washer. My end float comes up at .010 which is .003 greater than recommended. My washer was .047 thick and the distributor housing clearance was .037.

I can't do anything about that unless I shim the internal gear mount, but that's not recommended in the manual, so I'll just leave it at that.

However, I noticed that the rebuild shop that rebuilt everything back in 1993 has packing under the distributor mounting. The packing is .040, meaning that total end float would be .050 (.010 plus .040), when it's just supposed to be .005 to .007.

I'd hate to just eliminate the packing as if I'm smarter than the shop in the '90s, but it does appear that the packing was not needed. I don't like second guessing the pros.

Any wise thoughts?
 
Wise?? maybe or maybe not but in any case:

You are measuring the end float to find out how much packing material you need.

This will be affected by how tight you torqued down the distributor housing. You did tighten it up sufficiently. Right?

Just maybe last time your engine was rebuilt it really needed that much packing material. However it seems to me that that is quite a lot of wear, so maybe they put a few to many spacers there.

Now as for the 0.003" excess float, you also have to add in the thickness of at least one thin gasket, so the float will be a bit more than that.

Of course all of this could be thrown off if your washer wasn't flat enough. Or the distributor housing wasn't on tight enough..



Now (since the engine is still all apart) if you have an indicator gauge, you can easily double check this without playing with the washer.
Put the housing on (and properly tighten it up), and drop a long appropriate diameter socket into the distributor drive, and put the indicator dial onto the socket. Now from the bottom (oil pump side) push up on the distributor drive gear and you will be able to measure exactly how much float you have.

Yisrael
 
In practice, I don't believe this end float is all that important anyway. The resistance of turning the oil pump (which is considerable) combined with the angle of the gear teeth will hold the gear down firmly against the bushing in the block while the engine is running.

So, if it were my engine, I would just smear some Hylomar in place of the gasket and put it together.

BTW, new bushings are available (TRF 56405) but kind of pricy ($73.50).
 
TR3driver said:
In practice, I don't believe this end float is all that important anyway.
Click to expand...

Oh I agree 100% unless of course it is to tight in which case you can do lots of damage.
The large change in end float makes me suspicious that something interfered with the measurement, in which case the drive gear will be to tight. To tight and something will break.
So double check and of course as you put stuff together turn the engine over by hand every few steps to make sure that nothing is binding (a huge sudden increase in force needed to turn the engine over)
Yisrael
 
I had the same problem putting my TR3 back together -- too much end float even with no gasket under the distributor pedestal. Other than that flaw, the bushing in the block seemed fine. $73.50 seemed a lot to spend to reclaim a few thousandths of clearance, so I took a .010" piece of brass shim stock and made a washer to fit under the bushing. Drive out the bushing, insert the shim washer and tap the bushing back in on top of it. Then adjust the end float per the instructions in the book. So far so good. It'll be a few years before I can report on any long-term consequences of this repair.
 
As suggested by 70 Herald, I put an indicator gauge on a long socket and pushed the gear up from below.

Much like the washer test indicated, I show .012 of end play. In other words, independant verification of the end float.

So, I can ignore it, shim it or replace it. Replacing it seems like overkill for that gear, and I'd imagine it would be quite an operation to replace that bushing. You'd need a special drift and good luck not to crack the housing fitting a new bushing. Can you imagine cracking that housing? It would be the last time anyone heard from me on this forum.
 
Glad you were able to double check.

If the float really bothers you I would get a bronze thrust washer ~1/16" thick and put it between the original bushing and the gear. Available from McMaster-Carr for under $5 each.

However, if it were my engine I would probably ignore it.
 
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