Author Topic: Oil pump drive clearance  (Read 1013 times)

Offline mark

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Oil pump drive clearance
« on: 04.12. 2009 05:25 »
I have finally had my unmatched crankcases machined so that the cam and crank both spin freely but the fellow who did the work said that the timing bush had to be bored about 10 thou off centre (down and right looking at the bush) to line up with the drive side. My concern is that this will change the oil pump drive clearance and am interested in any suggestions on how to check it and how critical it is. I have assembled it and it seems to move freely along with the idler gear.
Regards
Mark
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Offline MikeN

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Re: Oil pump drive clearance
« Reply #1 on: 04.12. 2009 12:23 »
Mark,
  If your main bearing bush is now .010" down , then it will also put your timing gears out of mesh by this amount (unless your man has corrected this too?)
  I would also be concerned about ,and wish to check, the parellism of the crankshaft to the cylinder block joint face . Did your man machine or refinish this face?
  When I built up my engine I had a good matching pair of cases and I discovered that my cylinders were laying  over .0035" .which I thought unaceptable.
  It took me several hours to scrape it true.
  I sounds like your cases would also benefit from an alignment check in this area.
 Regarding the oil pump drive,  .010" sounds a lot to move a small gear like this out of engagement.
Mike

Offline mark

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Re: Oil pump drive clearance
« Reply #2 on: 05.12. 2009 02:20 »
Mike
      Top and bottom surfaces have both been machined. There is a small increase in clearance between the pinion and timing gear but not enough to concern me but I'll take advice on that. My main concern is how to ckeck on any change to the worm drive clearance. There is a remote chance that the pinion has moved in such a way that the clearance hasn't really changed and there is a small amount of movement between the oil pump and the mounting studs anyway so I think that I'll go down to the shed and if I stare at it long enough the solution should be obvious.
Mark
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71 Norton Commando Roadster 750


Australia

Offline terryk

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Re: Oil pump drive clearance
« Reply #3 on: 05.12. 2009 12:50 »
I think if you check all your gears for wear after years of work then 10 thou isnt a real lot. You should be able to get someone to turn the crank with a spanner on the drive side and hold the conrods if they fitted and have a close look at the main gear, timing gears and oil pump and check the meshing of them. You would probably need to have a bit of oil on everything though. Hope it works out for you.
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