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Help with distributor end-float

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Wire wheel guy Jim Smith
Baton Rouge, LA, USA   USA
I would appreciate some guidance in setting my distributor back in place with the required end-float.
I have read most of the threads I could find and think I have a pretty good handle on the math part ( whoever told me there would be no math in retirement was not telling the truth). I am just a little uncertain if I am correctly placing the flat washer for the measurements.
I am fascinated with the fact that this requires such accuracy in thousands of an inch, so there is no room for error.
The distributor was just rebuilt by Advanced Distributors, so that should be fine. There have been no alterations to the original low mileage engine and I have removed the pedestal and carefully cleaned and scraped the surface of the block and the pedestal.
Please see the two pictures below and tell me if I have placed the flat washer in the correct space.
Also, I am using a Pittsburg digital caliper for my measurements that likes to give me a different answer each time I try to take a measurement on the washer. They are all pretty close, but vary as much as .003 inches over 6 to 8 measurements.
I have three gaskets ( that I read should be called spacers) from Moss that also are a challenge to measure, but usually measure ar .005. One of the other threads said they cut there own out of .004 paper. Has anyone with a professional quality micrometer taken the real measurement:
Here are my before and after placement of the flat washer pictures. Please note that all I have done is to remove the pedestal and placed the washer on top of the distributor gear and have not removed it as the workshop manual instructed.
Thanks,
Jim

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dicta dick Taylor
Downey, Callifornia, USA   USA
In reply to # 1507142 by Wire wheel guy I would appreciate some guidance in setting my distributor back in place with the required end-float.
I have read most of the threads I could find and think I have a pretty good handle on the math part ( whoever told me there would be no math in retirement was not telling the truth). I am just a little uncertain if I am correctly placing the flat washer for the measurements.
I am fascinated with the fact that this requires such accuracy in thousands of an inch, so there is no room for error.
The distributor was just rebuilt by Advanced Distributors, so that should be fine. There have been no alterations to the original low mileage engine and I have removed the pedestal and carefully cleaned and scraped the surface of the block and the pedestal.
Please see the two pictures below and tell me if I have placed the flat washer in the correct space.
Also, I am using a Pittsburg digital caliper for my measurements that likes to give me a different answer each time I try to take a measurement on the washer. They are all pretty close, but vary as much as .003 inches over 6 to 8 measurements.
I have three gaskets ( that I read should be called spacers) from Moss that also are a challenge to measure, but usually measure ar .005. One of the other threads said they cut there own out of .004 paper. Has anyone with a professional quality micrometer taken the real measurement:
Here are my before and after placement of the flat washer pictures. Please note that all I have done is to remove the pedestal and placed the washer on top of the distributor gear and have not removed it as the workshop manual instructed.
Thanks,
Jim

Jim --- Others may disagree with this, but I don't think having measurements down to the thousandths of an inch is necessary for this application. What I have done successfully several times on different TR engines is this: Bolt just the distributor pedestal onto the engine block with NO shims. Reach down with a finger into the hole in the distributor drive gear. See if you can lift it or feel any movement. If none is present, add enough shims to where you can feel movement. I believe the purpose of these shims is so one doesn't mash the drive gear to the camshaft drive gear. Nor do we want so much movement (up and down) as to cause some timing fluctuation because of said gear lifting.

Dick

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
I'm no expert on TR6 engines; but my understanding is that the washer should go under the gear (meaning obviously the center hole is big enough for the shaft to go through).

'Pittsburgh' is Horrible Freight's house name, so the variation could easily be the caliper's fault. It's also easy to have a speck of dust or whatever that can affect the reading. But my guess is that your flat washer isn't really flat and the thickness actually varies that much.

.004" is about the limit of what I can feel, so if you can just barely wiggle the gear with the pedestal installed (and without the washer), it should be close enough.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

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brucejon Avatar
brucejon Bruce Jones
Santa Cruz, CA, USA   USA
1962 Triumph TR3B
1963 Triumph TR3B "Tupperware TR3"
1969 Triumph Spitfire MkIII
1972 Triumph TR6
My experience doing this this past summer on the spitfire is Randall is correct. Under the gear. Use a high quality washer that is flat, not one from the cheap bin at a big box store. Grade eight might be ok, or go to a machine shop. I suspect when you have it set up right your measurements will be more consistent even with a cheap micrometer.

I put a slight smear of grease on it to keep it stuck to the underside of the gear when fitting. Take a picture of how the gear is oriented before you take it out so you can out it back the same. Don't turn the engine over while it is out.

Here is what i did...
https://spitfiremk3.wordpress.com/?s=end+float&submit=Search

Wire wheel guy Jim Smith
Baton Rouge, LA, USA   USA
Thanks everyone! I probably just have a confidence issue having never done this before, but from your advise and the workshop manual, it seems that I should just be able to grab the gear with my fingers and pull it up and out. It has not been out of the block ever and may just be tight, but it sure does not just pull right up.
You can also see from the picture below that the gear connects at an angle to what I think is the fuel metering unit.
Shall I just get aggressive trying to pull it out or are there some tricks you can teach me?
Thanks,
Jim


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mmiano1 Michael Miano
Abingdon, VA, USA   USA
I have been able to remove the gear assembly by using a pocket type telescoping magnet. Mark the distributor edge or take photo's to show position both as currently installed and as it exits to be sure to return in the same orientation. ( the assembly will rotate as it is removed making it hard to go back right unless you mark its exit position.) Note that the gear assembly also drives the oil pump and must be aligned properly to keep the oil pump from being pushed down without properly engaging. Sounds tough but just take your time and don't force anything as you reassemble.



Edited 3 time(s). Last edit at 2018-01-14 09:57 AM by mmiano1.

poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
There is no fuel metering unit unless you have the Fuel Injection (PI) TR6, Jim.
The Distributor Drive Gear (DDG) is rotated by it's gear teeth meshing with gear teeth on the camshaft.
The bottom of the DDG engages the oil pump....that's a critical alignment. During installation of the DDG, the DDG and the oil pump must connect as the DDG rotates clockwise engagement with the cam...and if you want the distributor rotor to point at the correct angle with respect to spark plug wire #1 the DDG must end up about the same angle as it is now in your picture.
Rather than mess with it, I suggest you consider Randall, Dick (and mine) and forget about the decimal point approach and use your finger to determine wiggle.
You'll probably just need a couple of those spacers under the pedestal.
But if you feel you must remove the DDG in order to set the endfloat, then be prepared to help it rotate counterclockwise on the way out and clockwise on the way back in....about 90* as I recall.



Edited 1 time(s). Last edit at 2018-01-13 12:19 PM by poolboy.

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Wire wheel guy Jim Smith
Baton Rouge, LA, USA   USA
Okay, I am all in with the wiggle technique, especially since it is still factory set and probably does not need me fine tuning it.
So, I have tightened the pedestal back in place without a spacer. I put my finger in and can feel the slightest up and down movement. There is no movement side to side. This is without any spacers. Is it possible that I don’t really need one?
If that is the case, could I just add one spacer anyway?
I am still amazed at the fact that .005 of an inch could make any difference!
Let me know what you think and thanks.
Jim

poolboy Avatar
poolboy Ken D
Sandy Hook, MS, USA   USA
I once put a pedestal back w/o any spacers, but later when I went to reorient the angle of the DDG slot, the DDG gears were stuck pretty tight to the cam.
In this case regarding end float, I'd say "better too much than not enough".

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TR3driver Randall Y
Confusion, Los Angeles, USA   USA
Definitely possible, IMO. People put them back together without any extra gaskets, and the brass bushing under gear soon wears to match.



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild

Wire wheel guy Jim Smith
Baton Rouge, LA, USA   USA
Well, thank you everyone. Since I had slight up and down movement, I put it all back together using just one spacer.
It does not feel a lot different in the perceptible feel, but like poolboy said, Better to much than not enough.
I am now assuming the recommended spacing of .005 was just British humor.
On to the next mass confusion.

Jim

TR3driver Randall Y
Confusion, Los Angeles, USA   USA
In reply to # 1507278 by Wire wheel guy I am now assuming the recommended spacing of .005 was just British humor.
Well, we're talking about the end float on a gear that can move within that float and turns at half of crankshaft rpm. And my book says the clearance should be between .003" and .007" (meaning .005" plus or minus .002" ).
So no, I think some engineer really did specify that and not as a joke. Perhaps it doesn't need to be that tight, but timing scatter is a real problem and adds to tailpipe emissions.

As a side note, I've got a GM LT1 350 V8 where they were so worried about timing scatter that they redesigned the engine to have the distributor on the end of the camshaft; eliminating that skew drive entirely. (This was just before they went to crank-triggered ignition.) Giant PITA IMO. To change the distributor cap or rotor, you have to remove the radiator, both fans and the water pump!



Randall
56 TR3 TS13571L daily driver
71 Stag LE1473L awaiting engine rebuild
7? Stag awaiting gearbox rebuild



Edited 1 time(s). Last edit at 2018-01-13 09:03 PM by TR3driver.

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