E: Engine Twin oil pump fitting

litnman

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A combination of things happened here. Yes it required a reamer to clean the bore.
The outer main bearing was replaced using one with the thinner outer race which allows
OP31 to be installed or removed without interfering with the bearing race.
 

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Cyborg

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I have one more engine to do from bare cases up and think one of the first things I will do is install the pump sleeve in the naked case half. Hopefully I’ll actually remember that when the time comes. Greg, I’m only slightly surprised you say it’s the large race that hits. Both of the ones I have are from the smaller outer race. I suppose that speaks to the rather random nature of the machining that went on in there. Last night I took one of the old pump sleeves and offered it up to the (NOS) case. The sleeve had been previously cleaned up so although I didn’t measure it I assume it is slightly undersize. Anyway.. it didn’t want to enter the case more than a about 18mm, so no slip fit. Makes me wonder what actually transpired at the factory when they installed the sleeves. Was it a select fit or did they ream the bore or turn down the sleeve? Certainly does seem to be a road laced with land mines.
Anyone know roughly how much that bore expands when the cases are heated in the oven?
 

greg brillus

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It is nice to have a 1.00" inch reamer to check the bore. I pretty much check all the engines now, either new or original cases. The heating process is a double edged sword on account of the alloy and sleeve expanding pretty much at the same time, although on removal it definitely helps. Yes sort out the pump sleeve before anything else......... I do polish the edges of a new sleeve with a slight chamfer on the upper end to help prevent any kind of binding, with a little care and preparation the sleeve goes in ok, and so long as it is not too tight a fit, the plunger goes in and rotates with a little oil. If you de-bur most all of the edges of the brass sleeve, this should stop any nicks from scoring the bore anymore.
 

Cyborg

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In case you have to remove substantial material in the bore and your blunt reamer is unable to free cut to size you are entitled to use a secret toolmaker´s trick for restoring the reamer to achieve an individual size. You get a piece of carbide, like a lathe tool insert or a rod of carbide and run it along the cutting edge of the reamer under an angle like in my photo below. That way you create a tiny burr along the flute and so will be cutting the bore to your liking. Be cautious with forming these burrs, you can set the reamer to oversize two or three thou with this trick. You can check with your finger nail at the reamer edge for "size" .
Vic

Thanks for sharing that. I have a set of tools for refacing and putting a new burr back on the edge of scrapers that are used for wood working, so aware of the concept. I never would have thought that could work with a reamer. Guess that’s why I was told never to turn a reamer backwards.... it sort of reinforces that rule.
Of course out of the dozens of reamers in the drawer... no 1” . Guess I could make a lap and use the time saver compound if necessary. I only see one more pump in my future, so don’t really want to buy a reamer.

Off topic, but heating the cases to remove the pump always makes me think of Manx and Inter. The original pump bodies were made of mazak which expands more than aluminum or magnesium. Heating those cases to get the pump out is not a good idea.
 
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SteveO

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OK, the score in the new sleeve WAS caused by the outer bearing race of the outer (smaller) main bearing. I am going to have to grind this to take the edge off. My question is have I scrapped this sleeve by forcing it in? It's a long score as you can all see from the photo and is probably the cause of the plunger binding. It doesn't actually go over any feed holes, so would it cause wet sumping? Or maybe the sleeve is so distorted now that it's unusable?
 

Bill Thomas

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Hello Steve, Is the outer track of the outer bearing pushed right in ?
As " Litnman" said, The small outer track, There are 2 types of bearing, Some the outer track is thicker,
And you can't get the OP31 through it, Not that you often need to !,

The first bit of the far end of the sleeve is much thicker, I don't think you would dent the sleeve there ?,
Have you a " straight edge " You could line up on the outside of the sleeve, To see if it's bent,
I would not think it was.
If it was I would have a go a making it straight, Holding the far end In a tube Which is thicker and putting a nice fitting tube in the outer end, If it's scrap anyway, Anything is worth a try ??.
So I think it's down to finding a Bright Spot on the inside of the sleeve and Rubbing it with wet and dry paper.
 
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SteveO

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Bill, yes the outer track is all the way in. It's obviously the thicker one (see above). Once again this is something I didn't know, that there was a choice of two! I do now! I rolled the sleeve on the anvil of my vice; it doesn't appear bent, but of course could be distorted in a different way, i.e. dented inside. The plunger will go in so far, about until the worm teeth start to appear in the cutout. If I reverse it, the thick end goes into the wider part easily. The problem seems to lie at the far end where the graunch is. I could try wet and dry in this end until the nose of the plunger goes in. I don't know that I'm unduly worried about wet sumping (I own Nortons after all!) and in any case isn't wet sumping endemic to some extent with a gear driven pump? I'm more concerned about losing oil pressure to the big ends, I (and my finances) can't stand another failure here!
 

SteveO

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I have one more engine to do from bare cases up and think one of the first things I will do is install the pump sleeve in the naked case half. Hopefully I’ll actually remember that when the time comes. Greg, I’m only slightly surprised you say it’s the large race that hits. Both of the ones I have are from the smaller outer race. I suppose that speaks to the rather random nature of the machining that went on in there. Last night I took one of the old pump sleeves and offered it up to the (NOS) case. The sleeve had been previously cleaned up so although I didn’t measure it I assume it is slightly undersize. Anyway.. it didn’t want to enter the case more than a about 18mm, so no slip fit. Makes me wonder what actually transpired at the factory when they installed the sleeves. Was it a select fit or did they ream the bore or turn down the sleeve? Certainly does seem to be a road laced with land mines.
Anyone know roughly how much that bore expands when the cases are heated in the oven?
Not much I reckon (relative to the sleeve anyway), the fit didn't seem to alter much when the sleeve was driven out cold on mine, but my problem lies elsewhere (see above). Apparently the coefficient of expansion of alloy and phospor bronze is pretty close, so the sleeve should fit cold. Clearly they selective fitted at the factory, turning down the sleeve would weaken it. They may have reamed out to suit, but it would have been a ticklish business, probably too awkward for production?
 

Bill Thomas

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That's a strange one Steve, Have you got an old Plunger, maybe a bit worn, To give you an idea where the bind up is ?. As I said, I didn't think the far end would give trouble because the sleeve is thicker there.
What about finding a bit of bar/tube etc that is the right size of the smaller end,
If you can push that in and maybe it will show you the sleeve is bent ?,
i.e. If you look into the bigger end and bit of tube is to one side of the big hole ?, Sorry I am not good with words.
The other thing, You could unscrew the end cap of the sleeve, You said you thought it was loose ?,
To look down that end ?.
I think you are afraid to push too hard ??, In case you can't get it out ??, Or am I wrong :) .
 
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