>> >>Does it really cost £300 to do the tappets?<<
>>
>> If the cam lobe is bearing directly on the follower and the shim is under
>> the follower and on top of the valve stem then, in Bromp’s case the cost
>> doesn’t look out of order. All the clearances will have to be measured and in
>> the case of the no-clearance valves a shim fitted to give “some†clearance to enable
>> the correct shim to be decided. To change the shims the camshaft has to be
>> removed and new shims of the correct size bought, fitted and checked. With the no-clearance
>> valves this is camshaft out twice. The cam belt will be disturbed and the decision
>> made on whether to re-fit the old or fit a new one.
Yes, that will be it. No way of knowing what shim is going to be needed on the tight valves.
Incidental story - a friend nearby has a reasonably valuable classic with a 31/2 litre XK engine, 6 cylinder DOHC, shimmed head. The car was gone over last year, with the exception of the head which had been acquired relatively recently as a "rebuilt" good one and had done only a few thousand miles. The short engine was fully rebuilt at considerable expense. The clearances were checked and some shims changed, other than that the head wasn't touched. Since then, and with some fairly energetic use, the clearances have gone all over the place - some have as in Bromp's case lost all clearance and the compression is affected. Turns out that some bodger has actually adjusted the clearances at some point by shortening some of the valve stems, possibly in situ with a file! Now there's an idea...
Last edited by: Manatee on Wed 20 May 15 at 10:57
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