Camshaft bush oil hole

Mensch

Mensch

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Jul 1, 2020
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Hey all. Still working on the combat bottom end and just need to double check about the timing side cam bush. It looks to have been a scrolled type which has worn. But the oil hole on the bush barely lines up with the feed hole. I plan on using a new scrolled cam but should I be replacing the bush also?



The drive side is actually worse and doesn't even come close to lining up but does the scrolling on the cam feed the bush oil also?
 
Bunch of things to consider here .
Scrolled cam is to fit into a solid bush .
Yes the 2 bushes oil feed hole should have been lined up with any crankcase drilling oil drip supply .
The timing side bush should you decide to replace it is the easiest of the 2 to remove and reinstall using heat and cold . The drive side not so easy .
Some combat motors used a bronze thrust washer with bent over locating tabs on the timing side . These are bad news as the small tabs can break off . Since the engine is apart , if yours has the tabbed washer you can take pliers and break off the tabs now before they decide to do it themselves in the engine . A tab free washer is good , they were there only to prevent possible rotation .
Enjoy .
 
Mensch said:
Hey all. Still working on the combat bottom end and just need to double check about the timing side cam bush. It looks to have been a scrolled type which has worn. But the oil hole on the bush barely lines up with the feed hole. I plan on using a new scrolled cam but should I be replacing the bush also?



The drive side is actually worse and doesn't even come close to lining up but does the scrolling on the cam feed the bush oil also?
Click to expand...

You can run a drill bit through to open it up - probably don't really need to but you can - just be sure you don't leave a burr on the inside. I always change the timing side to the MK3 style - two shorter bushings, one from the outside and one from the inside. They tend to shrink a little when going in so light reaming is often needed. If you look at your current one, even if not worn much on the inside you'll probably see that the outside is worn flat with the engine case - this isn't the end of the world, but I like the MK3 style since you then have a thrust surface on both sides of the case. They are also much easier to put in, IMHO.

Also, those scrolled bushings in the Combats were barely scrolled. You sometimes have to look very hard to see any.
 
marshg246 said:
You can run a drill bit through to open it up - probably don't really need to but you can - just be sure you don't leave a burr on the inside. I always change the timing side to the MK3 style - two shorter bushings, one from the outside and one from the inside. They tend to shrink a little when going in so light reaming is often needed. If you look at your current one, even if not worn much on the inside you'll probably see that the outside is worn flat with the engine case - this isn't the end of the world, but I like the MK3 style since you then have a thrust surface on both sides of the case. They are also much easier to put in, IMHO.

Also, those scrolled bushings in the Combats were barely scrolled. You sometimes have to look very hard to see any.
Click to expand...
Thanks Greg. I might try to drill the timing side bush as the hole is close. The drive side bush hole is almost 90 degrees out from the oil supply hole. Even with scrolled cam journals is this not OK?
 
Mensch said:
Thanks Greg. I might try to drill the timing side bush as the hole is close. The drive side bush hole is almost 90 degrees out from the oil supply hole. Even with scrolled cam journals is this not OK?
Click to expand...
The scrolls move the oil across the bushing. If none is getting in, the scrolls are accomplishing nothing much.
 
marshg246 said:
The scrolls move the oil across the bushing. If none is getting in, the scrolls are accomplishing nothing much.
Click to expand...
That's what I thought. Was hoping some would make it's way along the scrolls protruding from the bush. Looks like the drive side bush will have to come out then
 
I don't see evidence of a scrolled bush as stated . Looks plain to me . A few scratches . T.S. and D.S should match .
 
Gotcha Greg .
06-2601 is the problem washer .
06-3020 as well as 06-3021 as presented new from Andover do not appear to have any scroll marks judging from their not so great 72 model photos . MK 111 I know well but likely a better choice .
 

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