Valve shims

michipons

michipons

Hero member
Location
Palma de Mallorca
Hi!

How do you measure the valves shims? all my Palmer (micrometer) are too thick to go in them! I thought about making a thinner rod/bar with an exact meassure and then extract it from the total measurement, but may be you have a better and more accurate solution? where to find a micrometer slim enough?

Are those shims specific for Laverda, or can I find them somewhere else? They are expensive enough for not having private stock of a few for each measure, but making an order to usual Laverda dealers for just a couple of shims... is a bit tedious.

Miguel
Have a nice weekend!
 
Hi Miguel,
I never had any issues measuring my shims with my good old Mitutoyo micrometer.

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Cheers
Jo
 
You need a micrometer with a 6mm end I believe.
As for another source of shims, I don't know. The car world obviously.

Paul
 
Change of shims interval depends on how many thousands of km ridden and state of valves, seats and guides. And oil....

Paul
 
My old 3C was ridden hard and didn't need much attention at all. Some of the later bikes seemed to need shimming every five minutes but that was probably 1979 syndrome.
 
In the past I've ordered shims from Wolfgang and Laverda Paradies.
But also fortunate to have a local supplier of NOS Laverda shims.
Here's my trusty Mitutoyo, it's been measuring Laverda shims for 45 years.
Shims for our triples have an inner diameter of approx 7mm.

Tom
 

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Hi!

here are my clearances, as I am re-building the engine completely, I wanted to put them spot on. I am trying to grind the valves manually, but if I have to rectify them in the engineering workshop, then I will have to adjust all clearances for sure, after complete assembly and re-checking clearances...

What do you think?

IMG_6568.JPG
 
Those clearances are prity good just a little tweak and you may just get away with swoping some. If you need to reduce the size get a piece of glass and some fine grade emery plus oil and away ya go
Regards Andy 😁
 
pf1 said:
My old 3C was ridden hard and didn't need much attention at all. Some of the later bikes seemed to need shimming every five minutes but that was probably 1979 syndrome.
Click to expand...

I've heard the early heads are made of soft cheese and the valves on my '73 & '74 3Cs probably need re-shimming every 20 mins... ::) ::)
 
AndyW said:
I've heard the early heads are made of soft cheese and the valves on my '73 & '74 3Cs probably need re-shimming every 20 mins... ::) ::)
Click to expand...
Well you heard wrong Andy. 74 3C and it was shimmed about 3 times between 20,000 and 90,000 miles. Each time it needed only one or two shims doing and that bike was caned.
 
pf1 said:
Well you heard wrong Andy. 74 3C and it was shimmed about 3 times between 20,000 and 90,000 miles. Each time it needed only one or two shims doing and that bike was caned.
Click to expand...

The alloy is old now and tends to contract.
Add crumbling cam pillars to that and youpiee!

Paul
 
pf1 said:
Well you heard wrong Andy. 74 3C and it was shimmed about 3 times between 20,000 and 90,000 miles. Each time it needed only one or two shims doing and that bike was caned.
Click to expand...

I concur with pf1. My 74 with a 75 cylinder head (swapped in 1977) valve clearances have been very stable over the decades. Even after some new valves/guides/springs in 2018 and a 5000 miles+ the clearances remain constant.  Yes, the cam pillars were very delicate. Changed those out in the 70s too.

 
If the valve seats in the head skull remain untouched, clearances will stay stable for a very long time.  Re-cut seats will recess quickly, this slows down/stops once the seat surface re-hardens a bit.  Wider seats will not recess as quickly as narrow ones, but are not as good flow-wise.

When guides are replaced, seats generally need re-cutting.  Good time to decide which way to go.  Shim sizes are usually in the lower range by now, valve seat inserts restore these to as-new with the possibility to optimally configure the seat angles.  Shorter service valves with re-cut wide seats restore some shim size but with sub-optimal flow characteristics.

piet
 
pf1 said:
Well you heard wrong Andy. 74 3C and it was shimmed about 3 times between 20,000 and 90,000 miles. Each time it needed only one or two shims doing and that bike was caned.
Click to expand...
Apologies, I guess I must've been imagining things again: I wish the trip through to Bellingen (and back again) a few years ago with *1588* in the back of a ute due to closed up clearances after only 1000km had been imaginary too along with Red's readjustment of shim clearances both ways to Cosi's place (and that's not so far from Brissy as Townsville is) the following year. *1173* barely made it from Townsville to Proserpine and back (700km round trip) before displaying the now familiar symptoms of diminishing valve clearance. In much of QLD and also South/Central Australia generally it's hard to 'cane' a Lav without losing your licence due to the wide open nature of the roads. EG it's possible to cruise along at 110-130km from one fill up to the next without even changing gear... I don't think this really does the older valve seats (mb valves too) any good: word on the streets of Southern Victoria seems to echo this sentiment..
 
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