Today I have installed the new Euro camshaft with a used cam tower not shaved with right spec for journals etc...
The cambox gasket have about~ 0. 015 in / 0.37mm of thickness.
Unfortunately, I was not able to have the correct valve clearance gap…
The lowest thickness shim I have is 3.30 mm and the valve clearance is only 0.04 mm (0.0015 in)
I have found a ticker cambox gasket (0.031 in / 0.78 mm) and lower thickness size shims (Starting at 2.55 mm).
Question:
What is the right valve clearance for the Euro camshaft # 4331512 ????
0.30 - 0.35mm is the standard paper cambox base gasket
I stock oversize cambox base gaskets in 0.75 / 0.85 and 0.95mm
I recently had to use a 0.75mm gasket in a service as I came across (ground) shims inside an engine, where one shim was down to 3.25mm, 6 of the 8 shims had been "surfaced" on the backside on a thicknesser / belt sander or similar ... I had to remove the cambox to put in a thicker gasket, and replaced all the damaged shims, dodginess like that goes straight into the bin. The head showed signs of having been "reconditioned" on this car, there was lots of permatex glue on the cambox base and cover gaskets, even though the car is a documented 75k km car, with history... didn't come with a file of receipts though so no idea who was responsible.
WARNING. DO NOT use shims with less than 3.25mm thickness, thinner than this the lip of the tappet bucket will stand proud from the shim, the cam lobe will strike this raised edge and destroy the lobe in short order.
if you're having to use a thicker cambox base gasket the usual reason(s) are;
1) the valve seat in the head has been recut too deep, this results in the valve stem protruding too far past the valve guide, this causes two possible issues... a) installed valve spring height is too tall, resulting in low seated valve spring tension and b) you get down to the smaller end of the range of valve lash shims
2) the valve itself has been refaced a lot, this sits the valve further into the seat, again causing two possible issues ... a) the valve spring installed height / spring tension problem, and (more importantly usually) the valve head "margin" becomes very thin... it doesn't have much opportun ity to drop heat, and the valve is likely to burn
3) the valve stem is stretching... I've seen this happen a few times, poor quality parts usually... I had a customer that over the course of about 18 months came in for service, / tappet adjustment.. each time one of the exhaust valves clearance would close up, even though less than 20k km before I had correctly set the lash, and only that one valve was closing up... turn out the head had been "reconditioned" a while before he started coming to me, and they had replaced one exhaust valve...
I like 0.30mm on the intake, and 0.40mm on the exhaust as the most suitable lash clearance.
On a new head, with fresh seats and stock length valves, the "nominal" standard shim thickness is 4.00, and the usual variance is about + or - 0.2mm at most. A really good valve job IMO should have the shims at less than 0.05 + or - from the "nominal" shim thickness. Cylinder heads vary a small amount in "thickness" even when brand new, as do standard camboxes... I have seen about 0.15mm difference from one uncut cambox to another...
SteveC
