10 replies to this topic

[Minigman]

Just fitting a new piper cam shaft into newly fitted cam bearings on my latest engine rebuild.

The cam won’t turn by hand but will turn freely when the timing gear is put on the end which adds leverage.

Is this something I should correct or will it loosen up a bit once it’s up and running?

Edited by Minigman, 25 September 2020 - 08:25 PM.

[Spider]

The Cam must be able to be freely turned by hand (without the added aid of the sprocket).

 

Running Clearance should be 0.001 to 0.002". It's not easy to measure, you would be best off using a narrow feeler strip.

 

Now you've had the Cam in there and spun it a few times, you'll have witness marks on the bearings where they need to be relieved. The best way to do this is with a bearing scraper but if you've never used one, practice on a few old bearing shells first. The Centre Bearing is always fun. Done use any abrasives as inevitably, some of the abrasive material will end up embedded in the soft bearing material, the journals on the cam will love that (not).

[Minigman]

Might just take it back to the machinest who fitted them. He had the cam too so no excuse really. I guess the pistons, crank etc have to come back out?

[Spider]

Might just take it back to the machinest who fitted them. He had the cam too so no excuse really. I guess the pistons, crank etc have to come back out?

 

Oh,,,,,   Yes, they usually do want the Cam so the bearings etc can be checked.

Ring and ask them how they want it back, but yes, it'll need to be stripped, I'd say so, if only for cleaning after it's sorted.

[Steve220]

Just fitting a new piper cam shaft into newly fitted cam bearings on my latest engine rebuild.

The cam won’t turn by hand but will turn freely when the timing gear is put on the end which adds leverage.

Is this something I should correct or will it loosen up a bit once it’s up and running?

What lube have you used? I find some engine building ones are so tacky, they create unwanted resistance.

[Minigman]

Just fitting a new piper cam shaft into newly fitted cam bearings on my latest engine rebuild.

The cam won’t turn by hand but will turn freely when the timing gear is put on the end which adds leverage.

Is this something I should correct or will it loosen up a bit once it’s up and running?

What lube have you used? I find some engine building ones are so tacky, they create unwanted resistance.

I used the MPZ stuff. You’re right, it’s like super glue and i did smother it.

[Chris.Williams]

When I get new cam bearings fitted I always leave the shop the cam so they cam reem the bearings. This is at the shops request I might add.

[Minigman]

When I get new cam bearings fitted I always leave the shop the cam so they cam reem the bearings. This is at the shops request I might add.

Thats exactly what I did.

[Chris.Williams]

When I get new cam bearings fitted I always leave the shop the cam so they cam reem the bearings. This is at the shops request I might add.

Thats exactly what I did.

Something is not right, consider taking it back for them to remedy.

[Minigman]

When I get new cam bearings fitted I always leave the shop the cam so they cam reem the bearings. This is at the shops request I might add.

Thats exactly what I did.

Something is not right, consider taking it back for them to remedy.

Yep will do.

[Steve220]

 

 

Just fitting a new piper cam shaft into newly fitted cam bearings on my latest engine rebuild.

The cam won’t turn by hand but will turn freely when the timing gear is put on the end which adds leverage.

Is this something I should correct or will it loosen up a bit once it’s up and running?

What lube have you used? I find some engine building ones are so tacky, they create unwanted resistance.

I used the MPZ stuff. You’re right, it’s like super glue and i did smother it.

 

Mine was exactly the same on both builds, using the same stuff. When i pulled the first one apart, there was little marking on the cam bearings. If you took it all off and used engine oil, there'd be less resistance. PERSONALLY - I wouldn't worry about it.