Camshaft end float

[DavidAll]

Hi,

new to the forum and rebuilding a 4.0 GEMS engine. I have a new standard camshaft and the block has a horseshoe thrust plate.
There is 5mm end float which is a lot more than the workshop manual specifies.
There is no groove for the thrust plate to run in it just sits on the front of the block and the cam can move between the plate and the back of the block.
Opinions I have received so far are that is too much and others that say it's fine and perfectly normal.
Any other thoughts?

[Rossco]

Are you measuring it with the timing chain on?

[DavidAll]

Hi Rossco,

I was following the workshop manual and measuring without cam wheel.

[Mc Tool]

Sounds like you have a cam shaft from an interm motor , they have a circular cam retainer that fits over the cam shaft and bolts to the block

.
This is a pic off the rimmer site , I have a 3.9 interm motor in bits so I can take a pic of the cam and retainer if you want .

[DavidAll]

Thanks Mc Tool.

The original camshaft is exactly the same dimensions as the new one and the horseshoe thrust plate is the original one and I would expect it to have the same effect as a full circular one. The engine is a replacement LR one so the age is unknown. The only oddity is the different colour marking.

The attachment IMG_20200318_082833183.jpg is no longer available

[ChrisJC]

RAVE says 0.05mm to 0.35mm, measured without timing chain fitted.

Chris.

[DavidAll]

I agree and then speaking to RPI they say 5mm is normal!

[DaveEFI]

I agree and then speaking to RPI they say 5mm is normal!

Nothing RPI says surprises me.

[DavidAll]

Ah! Any suggestions on a definitive answer or who to ask?

[ChrisJC]

I think 5mm is too much. I would go by the manual.
I suspect RPi think you said 0.5mm.
It's worth trying to understand why it's so much though. What is wrong and where?

Chris.

[DavidAll]

Thanks Chris,

it is strange there is really no where else to look at the moment. There is nothing at the back of the block, no mounting point or spigot. There is no way of mounting the short nose of the cam to any thrust plate. All a bit odd.

[sidecar]

I agree and then speaking to RPI they say 5mm is normal!

Nothing RPI says surprises me.

Totally agree, I would trust a word they say, in fact no matter what your problem is the RPI will recommend their ignition amplifier to fix it, including excessive camshaft end float!

[Mc Tool]

I guess at this stage I would do what is needed to reduce that 5mm to maybe .5mm. Just been thinking about cams being tapered and lifters being convex and chuck in 5mm end float and lots of things go out the window. I know the early 3.5s had bugger all stopping end float , mine has a projection on the inside of the timing cover that looks like it might bear against the cam sprocket, cept there aint a mark on it , and you can get thrust buttons to stop float . The whole area was a bit murky as there were issues re dizzy/oil pump drive gears if you leaned on them a bit hard.
Even if you running edis 5mm is just way to much.

[DaveEFI]

Oddly, I couldn't find a figure for end float in my BL SD1 manual. It could be when running because of the drag from the oil pump etc drive that it doesn't move at all in practice.

[DavidAll]

Thanks Dave and Mc Tool,

I am coming to that conclusion too as there doesn't seem to be a definitive answer. It can't come forward because of the thrust plate and with the centrifugal action of the chain and sprocket, maybe it can't go back either. Just fret about the manual description of .something rather than actual mm's.