DTR 1850 camshaft problem

[James467]

Ok so I really don't thing this damn car wants to be saved, I have had numerous problems this weekend trying the get the engine back together one of which was the water pump which had a chipped tooth out of the box.

Anyway I have built up the head, it has new valves, springs, guides and I have a new cam and followers as well.

When I install the new cam as soon as I torque down the caps the cam locks and I cannot move it at all.

So I tried a spare cam off a head which I know works, same problem, as soon as the caps are tightened down it locks up.

Both cams were cleaned, removed and reassembled with graphogen to just see if it was the cam lube but the same problem.

If I slack off the caps then I can rotate the cam

Nothing has happened to the caps or head and the old cam rotated fine.

I cant see any issues with binding, with the sprocket connected I cant turn the engine at all even with a breaker bar.

Any ideas?

[MIG Wielder]

Hi James, I would normally associate this sort of problem with the cam bearing caps. Are the ones you have numbered 1 to 5 left to right and are they the right way round ? I'm sure they are knowing your expertise. ( I understand not all were numbered in production )
When I had this problem some time ago ( not on an 1850 ) I fitted each bearing cap in turn and found just one that was causing the cam to run tight .
I also have a spare known good 1850 camshaft here. Would it help if I micrometered up the journals ?
Cheers for now,
Tony.

[James467]

Thanks Tony,

That was the problem, I put one of the caps in backwards!