I cannot find any specs in my literature for the sandwich plate thickness. I thought it might be a good idea to get the sandwich plate gasket surfaces lightly skimmed at the same time the engine block and crankshaft are being worked on by my machinist. It doesn't seem like losing 0.010"-0.020" would hurt anything, but you know what they say about assuming things. I'm wondering about the effect this would have on the oil pump inlet/elbow union and the interface with the oil filter housing. If they run a 0.010" skim on the bottom of the engine block and on both sides of the sandwich plate, there would be a 0.030" shrinkage between the block and lower sump– acceptable?

 

Quite Ok, but why? They were both machined by the factory, all they should need is a clean up. Pic of plate attached:

As you can see, machining this casting to any degree of accuracy would be extremely difficult, ditto the block, as holding it rigid while not distorting it during machining would, I believe, be very difficult. To improve on the factory I believe would be just about impossible. When I redid my oil pickup O rings I just cleaned up the surfaces with light wire wool and used the OEM gasket, 100% oiltight. If I did it again I would also use "gasgacinch" on the surfaces as well as the OEM gasket, as that stuff is magic:
https://www.gasgacinch.com/
The sump is a much harder challenge and this has worked very well for me:
https://www.jaguarforums.com/forum/x...ak-fix-234286/

 

Likewise,

WHY.??

I have never had issues with those surfaces in ALL the V12's I have been involved with.

2 of mine went back with NO gasket there, just a 6mm brad of Hi-Temp RTV. NO leaks, so I moved on.

 

Thanks gents, seems to me like a case of "overthinking it", which I'm guilty of far too often. There's some very light corrosion on the lower sump gasket surface so I thought it prudent to do something about it but as you both have said, probably best not to mess with the factory's work. I'll let the machine shop give it a good clean with the rest of the parts and use some light wool on the corrosion.

 

Goodo.

Smartest thing on here on a long time.

Over thinking is curable, well down here anyway, BEER, Shade Tree, BEER. Works every time.

Good on ya.