Measurement of cylinder head

[Malcolm C]

Hope you can help,on the Bristol stag clubs eventful trip to Ireland i.e. one stag caught fire another's brakes seized on.Mine started to run hotter (did not boil) and started loosing water.
Its just been diagnosed with head gasket failure.
The garage have sent the heads off to be checked,they say they are ok but should be skimmed.Before I bought the stag in 2003 the engine was rebuilt and the heads skimmed ,the garage would like to know if anyone knows of any measurement i.e. from the head face to a fixed part on the head so they can check if there is enough metal left to be skimmed again,also when it was rebuilt 2003 it was fitted with std head gaskets,so am I correct in saying that if they fit the thicker head gasket and they don't take off more that 0.55mm we would be ok,but would like any measurements just to be sure
Malcolm

[peterrc]

Hi Malcolm, Drew sent me this when I asked the same question.
Head Skimming (copied from somewhere)
In order to determine by how mich the heads have been skimmed, the head height between the bottom of the camshaft bearing (half bore) and the face of the head should be measured. A new head is 112.64mm, the specified minimum is 112.40 (obviously, not much skimming allowed). Any amount of skim below 112.40 should be compensated by thicker gasket(s) which add 0.5mm or, if still not sufficient, by addition of a shim (Tony Hart sells "Savershim" which works very well, in my case). A combination of standard gasket on one head (not overskimmed) and thick gasket on the other (if overskimmed) can also be used.
Other sources from Triumph (tech reprints) say minimum is 4,427" = 112,45mm
My Head before skimming = 112,45 mm = exactly the minimum
10thou = 0,254mm
Thick gaskets are 20thou thicker = 0,508 mm thicker

My measurements:

My RH Head after skimming
RH Front 112,00 mm = 0,45 mm under minimum
RH Rear 112,15 mm = 0,30 mm under minimum
With Thick Payens, my RH head is then effectively:
RH Front 112,00 + 0,508 = 112,508
RH Rear 112,15 + 0,508 = 112,658
My LH Head after skimming
LH Front 112,05 mm = 0,40 mm under minimum
LH Rear 112,15 mm = 0,30 mm under minimum
With Thick Payens, my LH head is then effectively:
LH Front 112,05 + 0,508 = 112,558
LH Rear 112,15 + 0,508 = 112,658

Peter, Sunny Cupar

[paulbell6]

Hi Malcolm, take a look at the thread I started entitled Valves / piston clearances and shim savers, which is currently on page 2 of the forum. There is a lot of info regarding the heads that may help you.

Regards.

Paul

[elvimto]

With skim cut heads the thicker Payen or similar gasket should get you back to where you need to be, depending unless they have been cut to the maximum and as has been stated the shim savers would be they alternate with the appropriate gasket.

cheers Stuart