31 replies to this topic

[imack]

There have been some issues with oil pump drives bottoming out in the drive slot in the cam in cross drilled cams plugged with a ball bearing and leaving no end float, hence my trying to eliminate that as a potential issue

[PoolGuy]

There have been some issues with oil pump drives bottoming out in the drive slot in the cam in cross drilled cams plugged with a ball bearing and leaving no end float, hence my trying to eliminate that as a potential issue

Now I'm totally confused. (not difficult to be honest)

[Lplus]

There have been some issues with oil pump drives bottoming out in the drive slot in the cam in cross drilled cams plugged with a ball bearing and leaving no end float, hence my trying to eliminate that as a potential issue

Had that on my 1100 rebuild, ended up grinding a small amount off the end of the oil pump drive spade.  BP255 cam with cross drilled lobes.  Easy to do as long as care is taken to ensure material doesn't get into the pump.

[PoolGuy]

Got ya, like Swiftune do. They seem to stuff the ball bearing 4-5mm down the drilling. Surely it’d be obvious if it was encroaching on the slot and subsequently the oil pump drive?

[Lplus]

Got ya, like Swiftune do. They seem to stuff the ball bearing 4-5mm down the drilling. Surely it’d be obvious if it was encroaching on the slot and subsequently the oil pump drive?

Not sure if it was a ball bearing or just not slotted enough.  Releaving the pump drive provided clearance and that was all I was worried about.  It was only because the instructions from the provider, Keith Calver, mentioned it that I checked.

[ACDodd]

Cam endfloat is a function of the triangular thrust plate, and the step on the rear of the sprocket. It's completely normal
To machine the rear of sprockets to be able to achieve the correct 0.003 to 0.007" endfloat.

The oil pump has nothing to do with setting cam
Endfloat.

Ac

[Lplus]

Cam endfloat is a function of the triangular thrust plate, and the step on the rear of the sprocket. It's completely normal
To machine the rear of sprockets to be able to achieve the correct 0.003 to 0.007" endfloat.

The oil pump has nothing to do with setting cam
Endfloat.

Ac

It does if the oil pump drive is long enough to push the cam tight up against the thrust plate.

[imack]

Cam endfloat is a function of the triangular thrust plate, and the step on the rear of the sprocket. It's completely normal
To machine the rear of sprockets to be able to achieve the correct 0.003 to 0.007" endfloat.

The oil pump has nothing to do with setting cam
Endfloat.

Ac

It does if the oil pump drive is long enough to push the cam tight up against the thrust plate.

Exactly that!
You're never going to adjust the endfoat by machining the pulley if there's an issue with the manufacturing of the cam or pump which is forcing the cam into the thrust triangle plate.
I set cam endfloat without the oil pump fitted, then fit the pump and recheck that the endfloat hasn't reduced and you have adequate clearance between the pump and cam drives.

[ACDodd]

Then you have a faulty component, the oil pump has nothing to do with setting the end float on the cam.

Ac

[Lplus]

Then you have a faulty component, the oil pump has nothing to do with setting the end float on the cam.

Ac

True, but since it could be either cam or pump causing the problem and trimming the oil pump drive removes the clash and allows the end float to be correctly set, it seems to be the best option.  I checked my BP255cam and oil pump as instructed by Keith Calver and found I had to trim the oil pump drive.  That solved the problem without having to return the cam or the pump with every chance of receiving something no better in exchange.

[Gaz66]

30 odd years ago when building mini engines I don't recall ever having issues like this.
You would have thought manufacturing tolerances would have got better not worse 😬

[imack]

The only ones I've seen any issues with have been the cross drilled ones which have a ball bearing pressed into the pump drive end of the cam to plug that end of the gun drilled shaft. It was 2 or 3 years ago and probably only a small batch of cams that were affected. Not all cams are produced this way, but it's always worth checking that adequate clearance exists.

[imack]

30 odd years ago when building mini engines I don't recall ever having issues like this.
You would have thought manufacturing tolerances would have got better not worse 😬

30 years ago most cams were probably reground BL/Rover cams and and genuine oil pumps being used.

[austinmayfair85]

Evening everyone.

I have had the camshaft sprocket machined and the cam end float is now in spec. Two further questions though:

1) The camshaft sprocket is now -0.05mm against the crankshaft sprocket.So whilst I have good camshaft end float, the crankshaft sprocket is now marginally proud of the camshaft sprocket (crank has no shims on). Is this enough to worry about? The only option would be to reduce the crank sprocket by 0.05mm as far as I can see.

2) There is a bit of a tightspot when turning the crank. It peaks when all the pistons are aligned in the bores. I have checked over the con rod ends. When loosening them one by one, it doesn't effect the tightspot, which makes me think it is piston related. This all said, it takes less than 10ftlbs to turn the crank through the tightspot. It's just not silky smooth. Again, anything to be concerned about here?

Grateful for any advice.

[Spider]

Given that 0.05 mm is 1.96" thou in real numbers and that the shims are only supplied in 0.005" thicknesses, it should be OK, however, in checking that be sure that the Cam is Thrust in to the Thrust Plate and also check at both extremes of the Crank Endfloat.

 

In regards to checking for Crank 'tight spots', that can really only be done first with the Crank only fitted to the Block and then with the Rods / Pistons fitted, but without Rings. If you have the rings fitted all you'll feel is ring drag, which will be it's highest mid-stroke and least at TDC / BDC.