Oh yeah, if there is enough material below the chambers of the TA Rover heads, if TA doesn't want to open them there are other companies that can CNC the chambers for you. But now that Mike Jr. is there to stay and eventually take over, they might have enough time/manpower to open them for you? Wouldn't hurt to call and ask if they don't respond here.
Yeah, I'll wait until I'm ready to buy the pistons. By then most of the block work will be done and maybe one of them will have posted on this thread. Probably after xmas though. I'll talk to Venolia first and see what they can do. Here are some photos of a 2 oz/60cc clay plug shaped and flattened to thicknesses of 1/4", 1/2" and 3/8". 30cc would be half the thickness. As you can see, 1/4" might work for the high compression build (1/2" pattern at half height) but spreads out way too much for the boosted application, covering nearly the full width of the piston and leaving little at the squish areas. The 3/8" depth is the only one that could be practical for both. Even that cuts into the squish more than optimally but maybe some re-shaping would give a satisfactory match. That's provided the piston maker even has or is willing to make a suitable dish die or is willing to make the crown an extra 3/8" thick and then mill the pocket. (The 3/16" required for the high compression build would possibly be easier to have done.) So there's what we're basically looking at. Like I said, it's a big dish, though maybe not beyond possible. Personally I think TA should at least take a look at their costs to provide a larger chamber head, a matching piston, or both. The 3/8" slug leaves about 10cc of extra metal on the crown so it adds about 27 grams or an ounce of weight to the piston. Not great but certainly something that could be lived with in an otherwise light weight piston. Half that with the high compression piston which is quite acceptable. Jim
I think it goes back to the old "open chamber/closed chamber" idea. The TA heads and the Rover heads are closed chamber designs whereas the 300/340 heads are an open chamber design which only have a very small quench area in a ring around the perimeter, interrupted by the valves. My guess is that to go from a 28 cc to a 58 cc volume in a closed chamber head requires a complete redesign of the head, the ports, the valve layout, coolant passages and everything else. I can't see that happening. Of course, I wouldn't expect to see Mike saying that, which is why I said it. Incidentally, I've been hearing that the 4.6L Rover heads can flow very close to what the 300 alloy heads can, so there is a reasonable choice of closed or open chamber in a similar flowing head. So, if you build the engine for the 4.6 Rover heads the TA heads then become a simple bolt-on upgrade path. Jim
