Cam bearing issue

[Garrick Clark]

Hi Guys.
I've had to strip my motor due to a tight bearing. I can fix that.
What I have found is the cam has too much end play. I have double thrust bearings fitted.
I need to measure it to get an exact figure but its over 25 thou easy. This engine is a bit noisy.
What do I need to do to fix this.
Thanks G.
 

[Jim Ratto]

usually when you check cam end play with new Mahle dual thrust, and a new cam, it's too tight, really too tight. I'm famous for ruining thrust bearings by sanding them trying to get end play to .002" and going too far. Last motor I did I had to buy a second set because I went too far.
What I do is assemble case with the 3 big main bearings installed with pins and all cam bearings, and cam. Torque the 6 12mm nuts to spec like you're closing motor up. The cam will probably be hard to turn now. I take a big screwdriver (like the big one you would use to remove bypass relief caps) and exert some weight "into" the cam drive flange while you turn cam, with screwdriver. This probably won't get you end play setting you need yet, but I check it with dial indicator @ cam plug end. It's probably under 0.0005" so you'll need to sand thrust surfaces of bearings to get there. Just take your time and go easy. I use wet/dry 600 on a thick slab of granite and WD40.
You might have a rough thrust surface on your cam that is eating your thrust surfaces up. I polish the thrust shoulders of the cam with 600 wet dry too as I am trying to get end play set. I shoot for 0.0015 to 0.002
You can oil slot the thrust surfaces too, just lightly file 2x 0.020" grooves into ea thrust surface and dress with Scotchbrite fine pad. I do this on all big cam motors.
Are you running helix angle cut cam gear or straight cut? What's your spring pressure?

[Garrick Clark]

Hi Jim thanks for the reply.
I have looked at the cam and it is rough were it makes contact with the thrust bearing. So i'll need to polish this area as you say. Is there a good way to do the polishing job on the cam. perhaps some 600 grit paper wrapped around a new bondo spreader would work.
I'm using a  helical style cam wheel so perhaps this is also putting side load on the bearing.
Think I might invest in a straight cut gear.
My springs are just hi rev singles.
I also noticed the wheel I'm using has a -3 stamped on it.
Also  after I  removed all case bolts for some reason I checked for play on the cam wheel  and noticed the cam  did wiggle a bit.
I just hope the case had separated a bit after removal of the case nuts.  If not the cam bores might have been align bored in the past without me knowing about it.