Oil chamber in lower rear of crankcase

johnmead

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Non-VOC Member
The oil chamber in the lower rear of the crankcase looks like it does not allow the captured oil to run back into the cases for return to the oil tank. Has anyone machined a slot or hole to allow the oil to escape?

John Mead
 

davidd

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VOC Member
John,

If you still have some concerns even after finding out that this chamber feeds into the oil pump, you might give Carleton a call. I think he drilled some holes to drain the oil in the racer, which is something that I have seen done to several hot motors. Obviously, the rate at which it drains cannot be too fast as it is the supply to the heads as mentioned.

I have had a problem with this chamber in the past. I have thought about drilling an oil drain plug so it can be drained. If there is a mechanical failure, like a big end, the chamber fills with metal particles and the best you can hope for is that they pump into the UFM. I installed a spin on filter prior to the UFM. I had another engine that had Castrol R in it and the R went moldy. I changed the oil five times (in quick succession)and the old R was still showing up. I would have thought that it would have cleaned itself much more quickly. The only sure way to clean it is to split the cases.

I should mention that there is a tiny grub screw that is usually staked in position near the oil pump that will drain the chamber, but it is too small to pass debris.

David
 
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vincenttwin

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VOC Member
A question along the same lines , the oil scraper platform at the bottom rear of my A cases was broken away , it should scrape the oil off the flywheels and dump it into the small oil pump pick up area , I have the cases apart should I rebuild it so it does scrape or just let it flow . any ideas.

Peter
 

Bill Thomas

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VOC Member
Hello Peter, I have run Small flywheels on a C twin, which would be the same and had no trouble, Cheers Bill.
 

timetraveller

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I can confirm that two other racing engines that I know of also run small flywheels which are no longer a close fit to the scraper but the chamber still exists. It probably depends upon how much of your scraper is missing as to whether it needs to be built up. If it is just the edge then you can probably do without it but if the break is right down to the lower part so that the chamber's holding capacity is compromised then it will need some remedial work.
 

davidd

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VOC Member
Peter,

I can't argue with the above. You could re-read Phil's article on the "A" Comet case design in MPH 440 at 13. He talks about the scraper design. I think you may be able to do without it, but if it were mine I would probably fix it.

David
 
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