If someone has a '79 T140D or T140E parallel port head sitting on the bench, could I please ask you to measure its thickness (head gasket to rocker box surfaces) and then post the result?
I am struggling with pushrod tube leaks on my '79 T140D, which I bought in pieces. My (former, now) machinist, without asking me, told me he cut my head .060 to "flatten it" when he was doing valve guides. However, when I measured the head, it came out to be at or very near the 2.755 from the head gasket to rocker box gasket surfaces John Healy mentions in his very helpful article on curing pushrod tube leaks, at http://vintagebikemagazine.com/technical-articles/push-rod-tubes/
This makes me wonder if the head thickness of these heads differs from other splay port heads. With the standard head gasket, I only had about .040 squish, which makes me believe the head has been cut, but perhaps not by as much as I was told--more like .020 or .030 because this is the more or less the squish I ended up with early on in the life of my race engine, by using a thin .020 head gasket and thin base gasket.
The PO gave me a new JRC cylinder and pistons, and I have been told the height of the pushrod tube shoulder on those JRC cylinders can vary. If the head thickness measurement doesn't shed light, my next stop will be to remove and carefully measure the JRC cylinder and compare to the figures John put in his article for the tappet block shoulder thickness (.790-.800), and possibly to return to the stock cylinder if it is incorrect, and/or machine .020 off the tappet block, etc.
I have had this thing apart 3 times this summer trying to fix this, and I have put a .080 head gasket, and thin square section o rings in this, and it still cuts the square section o rings through, and it still leaks. I am trying to get a handle on what is going on, so if one or more of you could measure the thickness of a parallel port head, and post it, I would appreciate it. No need for other advice, a measurement is all I need. Thanks!!