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Triumph cam to bushing clearance???

8K views 18 replies 11 participants last post by  slydog28001 
#1 ·
replacing the cams and bushings in my 67 650. im looking to get the cam bushing reamed to size but i cant seem to find a spec for what amount of clearance I should be running. Im using Megacycle cams and new bushings.

Any help would be great as im looking to get started on this today.
thanks
 
#3 ·
the bushing should not be reamed until it is pressed into the cases,
we have a Triumph cam reaming tool, it uses a ream that measures .813 on the inner bush and on the outer bush we press a ball that is .875 through it. but the tool has line boring collars that make it all work well after you bolt the cases together.
New cam bushings really make tappet adjusting much easier.
 
#7 ·
I had a BSA in here the guy took lapping compound and lapped the cam in place, then when he fired up the bike that shit went through the engine and ruined all the bushings and bearings.
so there is more than just the right way to do things.
 
#10 ·
^X2; the ball deal can be pretty accurate.

I've run 'em through a bunch of valve guides, and a bunch of lifter bores.

Works good; shouldn't go off from straight unless you really push to one side. I'm sure somebody has managed to do so, even though I haven't...

The only thing I've run into was on some lifter bores (iron block V8 engines), I found that if the ball broach was a tight fit, that it'd tend to make a bit of a tight spot where it first goes in. I'm talking a fraction of a thousandth here, but enough to notice when the lifter clearance on some new lifters was just over a thou.

I don't know how to explain in words what I think it's doing, but my suspicion is that since the ball was bigger than the hole, it'd tend to push some of the material from the edge of that hole when it started in.

But, a broach is a good way of making a fairly consistently sized hole. Goes fast, no chips.

-Bill
 
#11 ·
I have used a small 2 blade spring loaded hone that I use for Triumph master cylinders.. Seemed to work out good...Also works for small end bushings.. I find that the only time a valve guide, or cam bushing has a tight fit, is if it is whacked or pressed into place without enough heat being used..
 
#12 ·
Dont trust the reamer or ball as is, make sure you put the cases together and check to see if the cam turns nicely and drags oil into the bushing as it turns. Then do the yamabond thing. Trouble is alot of places sell "ream type" cam bushes and regular ones. If you know about the "ream type" you might be temped to believe that the regular ones are useable as is without anything. This can be a bad assumption. I have also found that Megacycle cams need a little extra reaming or honing as they have prouder journals than stockers. I have never seen one that did not need some kind of attention after it was installed. I think that is why they made the tool in the first place.
 
#13 ·
i do have the ream type bushings in there. Im still not to sure the best way to do this. I don't want to buy the ball type if im just going to have to ream them more to get a perfect fit on my megacycle cams. Or it goes to far and I have to buy a new bushing. Im thinking of reaming the timing side to .0010/.0025 clearance, then turning a sleve the slips in the timing side busing to hold the reamer shank to do the other side????
thanks for the help
 
#17 ·
http://www.jockeyjournal.com/forum/s...ad.php?t=34309

i posted this same issue some time ago... I ended up purchasing 3 sets of cam bushings and while they pressed in fine when it came time check the fitment it got ugly. used a sharpie marker and covered the ID of the bushing....put cams in, doweled and bolted case halves together.... spun cams numerous times.... took apart and there were high and low spots where the cam never contacted the bushing... and the intake cam was sloppy as hell while the exhaust was tight.. and i did measure the cams and ream the bushings accordingly (most sources said not to even ream them)...after repeating this process a few times i ended up tired of wasted money on bushings and ordered up sae 660 bronze and machined them myself........as for the cam that spun the bushing, checked the bore to see if it was out of round (wasn't) and made the new bushing OD .0015 over that for a nice interference fit. i felt the manual skimmed over this subject as if it were of minimal importance..... seems kind of critical to me....much like many of the other shortcomings of triumph engines....like the heads with cast in valve seats that are WAY off center...but thats another day.....

if you do a search i think i recall many other threads with this same topic...

before i decided to make them myself i searched to see if i could purchase bushings with a smaller ID so I could size them, no luck.... problem was the inner dimension after pressing them in was too close to the final dimension..... really didn't take that long, but the results were 1000 times better...oh, and i'm running megacycle 51065 cams....and look out for piston to valve clearance....
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