Too small lifter?

Matt80 · Post by **Matt80** » Tue Sep 27, 2016 3:24 pm

Hi, I'm afraid I bought the wrong camshaft
is there a way to be sure of that? Because it seems to me that the lifter is too smal diameter for the camshaft, isn'it?

Thanks

rally · Post by **rally** » Tue Sep 27, 2016 3:41 pm

Who and where did you buy this cam and lifters from? Did you contact them to make sure this was correct for your application? Very simple.

MadBill · Post by **MadBill** » Tue Sep 27, 2016 4:24 pm

OK, first, that's an OHC set up, yes? So it is normally referred to as a bucket or cam follower, not a lifter. Second, your photo shows the lobe positioned with the narrowed (for friction reduction) base circle in contact. It would be instructive to see it with the lobe at or near full lift. Third, yes, if the shiny area is indeed the lobe/bucket contact zone, in addition to the bucket not rotating as normal, it seems to run right off the OD of the latter. Does the other side show the same waer? Ditto all the other lobes? Fourth, it appears the base circle of the lobe is still rough cast rather than machined.

pdq67 · Post by **pdq67** » Tue Sep 27, 2016 8:53 pm

What engine?

pdq67

Post by **CamKing** » Tue Sep 27, 2016 11:06 pm

yes, the max velocity of the lobe design is too high for the bucket diameter, and the lobe is riding off the edge of the bucket.

Matt80 · Post by **Matt80** » Wed Sep 28, 2016 2:01 am

MadBill wrote:OK, first, that's an OHC set up, yes? So it is normally referred to as a bucket or cam follower, not a lifter. Second, your photo shows the lobe positioned with the narrowed (for friction reduction) base circle in contact. It would be instructive to see it with the lobe at or near full lift. Third, yes, if the shiny area is indeed the lobe/bucket contact zone, in addition to the bucket not rotating as normal, it seems to run right off the OD of the latter. Does the other side show the same waer? Ditto all the other lobes? Fourth, it appears the base circle of the lobe is still rough cast rather than machined.

Yes, DOHC and buckets. The shiny area is the white marking pen I used over the lobe to show the contact.

CamKing wrote:yes, the max velocity of the lobe design is too high for the bucket diameter, and the lobe is riding off the edge of the bucket.

Just discovered that cam was for a 2mm bigger bucket, so we have no choice other than remove it. Thanks

Matt80 · Post by **Matt80** » Wed Sep 28, 2016 3:51 am

CamKing wrote:yes, the max velocity of the lobe design is too high for the bucket diameter, and the lobe is riding off the edge of the bucket.

Could I rectify the cam lobes to make it work or is there some kind of anti-wear surface treatment?

Post by **CamKing** » Wed Sep 28, 2016 9:51 am

Matt80 wrote:
CamKing wrote:yes, the max velocity of the lobe design is too high for the bucket diameter, and the lobe is riding off the edge of the bucket.
Could I rectify the cam lobes to make it work or is there some kind of anti-wear surface treatment?

You have 3 options.
1: Machine the head for larger buckets.
2: buy a cam that's designed for your bucket diameter.
3: have your cams reground with profiles that were designed for your bucket diameter.

ozmuscleowner · Post by **ozmuscleowner** » Thu Sep 29, 2016 6:20 am

Matt80 wrote:Hi, I'm afraid I bought the wrong camshaft
is there a way to be sure of that? Because it seems to me that the lifter is too smal diameter for the camshaft, isn'it?

Thanks

I'm confused, what engine is this for?
Is it a motorbike head or something like a cosworth head?
In the past I have seen OHC engines with "lash" so the backside of the camshaft was not ground as in the picture, you can also clearly see the head has clearance for the lobe to swing down onto the bucket?
what is actually the problem? How/why do you think the bucket is too small?

the white markings are paint to show width of lobe, the bucket appears fine in the picture?

Post by **CamKing** » Thu Sep 29, 2016 10:18 am

ozmuscleowner wrote: what is actually the problem? How/why do you think the bucket is too small?

the white markings are paint to show width of lobe, the bucket appears fine in the picture?

He painted the lobe white, and the white on the bucket, shows where the lobe is riding on the bucket. The problem is the white goes all the way off the edge of the bucket. If the lobe rides on the edge of the bucket, and not the face of the bucket, it will wear the cam and bucket out. If the cam lobe was designed for that diameter bucket, the white transfer from the lifter would stop short of the edge of the bucket.

ozmuscleowner · Post by **ozmuscleowner** » Thu Sep 29, 2016 6:49 pm

Thanks Camking, now you have pointed that out I see what you mean, its clearly overlapping the bucket.I actually thought the white paint was painted on there to show the width of the lobe, yes if its going to the edge its too small(the bucket or lobe too big)

CharlieB53 · Post by **CharlieB53** » Tue Oct 04, 2016 1:44 am

We ran into a problem like this using hot aftermarket cams in the late 70's building the 900 and 1000 Kawasaki DOHC bikes that used a shim on top of the bucket. The higher lift cam lobe getting too close to the edge of the shim it would 'cock, lifting one side of the shim, spit it out, breaking parts.

The solution for us was to switch to the 750 style buckets that had the shim UNDER the bucket.

PITA reshimming as you had to pull the cams instead of using the handy tools to compress and change shims on the 'top' shim style.

Oh well, we pay for performance.

You simply have too much cam for the application. Not a good combination.

Don Terrill’s Speed-Talk

Too small lifter?

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