OST-030: a case in point

[oldeskewltoy]

So with OST-031 now @ the machine shop getting its valve job and surfacing we delve back into OST-030


I've gotten the head back from the machine shop, they have provided a minimum resurfacing .003", to add to the previous clients report of a .008" resurfacing, the current surface is not quite @ .011, closer to .0102". This head is now 115.74mm thick, having had a total of .26mm removed.

Typically with a 10 thou cut you can expect chamber volumes to drop to about 35cc, the deshouding adds about .4cc, to gain volume I had the valve seats machined an extra .003" to gain 1cc in chamber volume, this lowers the valve on the seat allowing for a bit more volume in the chamber. The valve tips were cat an equal amount so use of more common shims sizes is retained.



So right now the chambers sit @ 36.4cc (1/10cc tolerance)

oldeskewltoy;6155985 Wrote:All the cam journals look pretty much the same as this...


Since MR2tailbreaker noticed a "small" problem in his cam and journal clearances using the Poncams, I'll be checking these journals for similar issues.....

The FSM(BGB) states the cam to journal clearance to be .035mm to .072mm, with nothing greater then .1mm




Using the Plastigage PL-X - The PL-X range is a bit on the tight side for measuring the whole range of the cam to journal - a bit too small for perfect accuracy, but in this case it works adequately.



This is one of the measurements, you can see it is quite a bit narrower then .045mm which is middle tight of the span in the FSM.

By carefully surfacing the cam cap "feet" we can get this dimesion closer to the center of the specification





Here is a 2nd journal going from a bit loose....




to middle of the spec




Of course the worst one I didn't get a photo of, that was #5 on the intake side... farthest from the oil supply, it was so loose that most of the Plastigage thread was intact when checked, and it too was brought into spec.


Now that the cam journals are all within tolerance, assembly can begin.....



More to come.....