The V8 Owners Forum -

i have just fitted a new cam to my 4.0 range rover have followed workshop manual when i try to turn the engine over by hand it gets tight in one spot it will go by this point with a bit of force there are no spark plugs fitted either. Is this the norm or should i be looking at something else. Tried it with out the cam chain and no rockers fitted it, is still the same tight in one spot.

is the tight spot once per revolution or more/less than that.

yes it is once per revolution

gunnwoom wrote:yes it is once per revolution

Have you disturbed the bottom end/pistons at all while fitting the cam?

Is it a complete rebuild?

Try and work out which cylinder is at tdc when it gets tight, as you may have a valve bent or jammed down. Then see if the valves on that pot can be pushed down, or otherwise look 'normal'.

When you first timed the cam did it turn over easy, or was the tight spot there straight away.

Did you shimmed the rockers, sometimes needed on certain lumpy cams?

Dont think its cam related, I think you have a problem somewhere else. You probably only noticed it because of the work your doing just now.

Oval crankshaft? or an off-round big end bearing could cause that.
I'm not sure about the 4.0, does it have a longer stroke than the 3.9/3.5 engine? if so are any of the counter-balances slightly touching the casting?

What I'd do is undo each bearing in turn and try to turn the engine, and find it by process of emimination.

havent disturbed anything else, it is just a cam swap

ts just a standard cam have watched the valves from above and all seem to return with no probs but even with the rockers removed its hard to turn

As per katanaman. Unless you know it only started after the cam swap i.e you turned it by hand before and it was OK, you can't assume anything. Plenty of very knowledgeable people here to help you through it.

going to have a look at bottom end see if anything can be spotted

cant see anything bottom end from a quick inspection however it gets tight as number 2 cylinder reaches the top of its stroke i can see the inlet valve working and returning to posistion but obviously cant see the exhaust valve is this a head of job to check

I really don't think its anything to do with valves and stuff specially since its the same with the chain and rockers off. No valves are open then so cant hit. Something is bent, oval or the likes and like I said was probably like this before just you never knew. Something to try is get someone to stick it in gear and foot on the clutch, give it a turn and see if its the same. This will let you know if its transmission related or not. Taking heads off probably wont tell much as its unlikely to be bore related, possible but unlikely.

gunnwoom wrote: Tried it with out the cam chain and no rockers fitted it, is still the same tight in one spot.

So it's just a cam, sprocket and followers in the block? Is it a serp engine with the strap to retain the cam? If so remove the strap. If it's still stiff the cam must be bent or you've damaged a shell when fitting the cam. I'm assuming a lifter isn't sticking in it's bore and everything's lubed up Nothing dropped down into the lifter bores?

Boosted.

Boosted LS1 wrote:

gunnwoom wrote: Tried it with out the cam chain and no rockers fitted it, is still the same tight in one spot.

So it's just a cam, sprocket and followers in the block? Is it a serp engine with the strap to retain the cam? If so remove the strap. If it's still stiff the cam must be bent or you've damaged a shell when fitting the cam. I'm assuming a lifter isn't sticking in it's bore and everything's lubed up Nothing dropped down into the lifter bores?

Boosted.

I am reading it that he has disconnected the cam completely by taking the chain off and removing the rockers so the cam isn't turning at all. Have I read it wrong?

no your reading right it is just the same with the cam not connected and the rockers removed