Timing gear crankshaft shim (s)
Turbo Mini Forums

Just set up the cam timing and sorted out the right offset key but decided to do a final check across the faces of the sprockets and it was 20 thou out (sorry for old units:))

Never seen it that bad so pulled the shim pack off the crank to measure them and there's already 46 thou of them and I need another 20....

Is it usual to need 66 thou of shims ???

I've measured the width of both sprockets (where I put the straight edge) and they are within 1 thou.

Block, crank and cam are all from different sources but even so.....

Schrödinger's cat - so which one am I ???

Have you got one of them thick payen gaskets between the block and the timming plate? The thickness of some of these is unreal! I find there are quite often two in the kits. A thick and a thin. I always go for the thin now. Had a similar scenario about a year back. Its the only thing I could put it down to.

YES... !!!!

Why didn't I think of that, I had the same problem earlier this year with diff output flange gaskets being thicker than normal so needing far more shims than normal to pre-load the diff bearings.

The gasket I used behind the timing plate was thicker than I expected, just didn't link it to the problem tonight....

Working too late, off to search the shed for shims.....

Schrödinger's cat - so which one am I ???

Check your cam for endfloat first! I found the cam to have alot of movement between the pump and the cam retaining plate. Worryingly (I think thats a word) so.

No, I already did the cam and crank end float when I started the build and re-checked it when I found this problem, both well within spec, it's obviously the gasket - the cam end float is determined totally by the triangular plate behind the sprocket (runs on the end of the cam and the back of the sprocket) so the oil pump isn't relevant, actually best not to fit the pump until the cam is in right.

But you've put my mind at rest and I've dug out one of my spare cranks, just need to get the key out and see how many shims it has.....

Schrödinger's cat - so which one am I ???

Cool. Its a horrile sinking feeling when things dont add up!

Except I've just pulled the key out to release the "shims" off my spare crank and it's just a single 6 thou shim.... (and I need 20 thou)

Was Leyland's build quality really that poor, 46 thou on one crank and 6 thou on another ????

Schrödinger's cat - so which one am I ???

It is called selective assembly LOL

My Dad was a BL apprentice!

I've never found excessive camshaft endfloat. Also, I don't understand why this is so dangerous. Yes, the chain will wear more, but apart from this?

V,

I think it has to do with follower wear,

the cam lobe is slightly offset from the follower bore, and ground at an angle, I belive if the cam moves around it screws this up and weasr the followers.

I wasn't aware that Minis did this (as the follower diameter is relatively small) but it's common on other engines with larger followers to offset the lobe slightly from the follower centreline to cause the follower to slowly rotate and keep wear even.

Anyway, it's together now with a pack of 10 shims and aligned to within 3 thou (the shims only seem to come in 6 thou so it has to be a compromise) in favour of getting better as the thrust washers wear (as they must with a grey cover!).

With the offset key, final timing was 110 (or 290) -0.5, -1.0. -0.5, -1.5 degrees (I measured all 4 inlets) on a brand new chain so should be spot on after initial stretch.

Schrödinger's cat - so which one am I ???

The follower is convex, so that'll rotate anyway.

???

how does that work?

Search button wins yet again! Was wondering why I was getting 20 thou of end float on my cam! now just to find a thin gasket.

Own the day

You won't get less endfloat with a thinner gasket. The cam is located around the 3-bolt cam retainer plate anyway.

The Viking Is right CAM end flot is set between the cam gear the 3 bolt retainer and the face of the big bearing journal of the cam.

As both the above, try a new 3 bolt plate, it has whitemetal on one side (to act as a thrust bearing against end float) and this wears.

What the thinner gasket does is it stops the cam sprocket being quite so far away from the block so you need less shims behind the crank sprocket to get them in line.

Schrödinger's cat - so which one am I ???

There is no ware on the plate! and as I understand it you cant buy differing gauges of plate.

Own the day

The only other way to reduce cam endfloat then is to shorten the timing gear slightly.

Edited by Vegard on 21st Apr, 2009.

Schrödinger's cat - so which one am I ???

I've just fitted my swiftune vernier pulleys and the cam gear is 15 thou lower than the crank gear. I've removed the only shim that was under the crank gear. Anything obvious that I am missing, as the only way I can think of solving this is to have the crank gear machined?

I found with my Swiftune Verniers that I needed no shims at all for the pulleys to be in line

are you using a genuine front plate and gasket? The thickness of the plate and the gasket will affect the position of the cam gear relative to the crank sprocket. I doubt swiftune would be the sort of company to manufacture a product with an incorrect tollerence, well I like to think at least.