Cam Installation Question

[wdills]

Continued work on my engine this morning. My reground cam came in this week so I decided to install it. New cam bearings were installed by the machine shop.

I made sure the bearing and cam surfaces were clean and applied some assembly lube to all surfaces. I slid the cam in and everything felt normal most of the way in. When the cam was about 1/8" from being in all the way in, it turned nice and free. When I push it the rest of the way in (to the point where the locking plate holds it) the cam becomes tight and doesn't turn easy anymore.

I put my old cam in and it does the same thing.

Do I have a cam bearing problem? Never installed one before so not sure how free it should turn.

[(S)]

You may need to take the block and cam to the shop and have them fit it for you.

[Mike Van Veghten]

Sounds like one bearing (the last one) has a burr, or maybe is a little cocked.

I don't suggest "fitting" the cam. If this means removing any material from a bearing surface...unless it is just a small burr. It could bit you in the butt down the road with low oil pressure.

Best to as noted, have your machinest recheck and replace as required.

Mike

[Bob Andrews]

Not Stude-specific, but I have always liked the shop to assemble the lower end for me, for just this reason. If there's a problem they're right there to A. See for themselves it wasn't a problem I created by screwing something up and B. It's already where the equipment to correct a problem is. The cost to have them do it is usually not much, and well worth it- especially when a problem crops up. They do it every day, so they know how to avoid the pitfalls, like double-checking clearances, not touching bearing surfaces with your fingers, not accidentally damaging a ring on assembly, getting the cam degreed correctly, etc.

Food for thought for the future.

[PackardV8]

If you want to know where it is tight, get some machinist's dye called Prussian blue. Paint all the journal surfaces with it, install the cam, rotate it a couple of turns and withdraw it. The tight spots should have the bluing wiped off the journal.

jack vines