one finger john wrote:Because of the use of larger intake valves with as-cast valve pockets it would make sense that machine work on the pistons would be required. The pockets would probably work with smaller valves and a smaller, less aggressive, cam. This is in a period of time which should be in the initial phase of mock-up instead of in the later, almost finishing-up phase of assembly.
As a matter of fact, I like the idea of using the cylinder head as a fixture to machine the pistons. The "as it is" relationship of piston to valve is easier to control and, in my opinion, a better fit. A true custom fit between valve and piston as far as clearances, with the parts that are being used.
It would have been better in the earlier stage before the crank assy and cam assy were installed with lube, but so be it. I also would of used clay to determine the true shape of the pockets (or even the clearances of piston to combustion chamber, bigger piece of clay for both intake & exhaust).
Larger valves used with as-cast pistons. Always gotta' check em. Large aggressive cam. Always gotta' em. Extra machine work to clean up (to be sure there are no bits and pieces left in the engine) but at least it is being corrected.
I think Mad Cad sometimes gets lost in his numbers and blathers on a bit, but he'll get it done and we will see how it turns out.
The pistons are designed for BOOGIEMAN heads..
With the valves I have in them.. The pistons are not some generic Cadillac forging..The reason the alignment issue happened it due to the head being decked .120
I did not change the depth of the eyebrow just corrected
it's location.The as figured valve drop was something over 1/2"
prior to my cutting the heads..even wits the cut of 1/8" I should have had plenty..it's the fact that in cutting the deck the valves
move closer to the piston but NOT at the angle they do thru the
guides that this changes the position relative to the piston
I did not realize this prior to having the heads cut ..
Cutting pistons in a assembled short block is a last resort and is a nitemare.. However you are right in that the in head cutters are good because they are precise in location for the eyebrow.. A point to add to that is that there are variances in valve locations from cylinder to cylinder let alone head to head.. The eyebrow the cutter made is clearly a tiny bit different from one cylinder bank to the other as I used the right head to cut the right bank and left on the left.. The only way to truly know you have clearence on all 16 valves is to do as I have done and check all 16..
All of this has been explained in my previous posts..