Although I have done a search and asked around, I was under the impression that with a untouched deck on the block or the mating head surface that Toda B cams could fit valve-piston interference with CTR pistons.

I tried this today with exactly this setup (I do have .025 overbore cylinders) and both exhaust and intake sides developed interference.

Will going to a Cometic or other 1.0 mm headgasket give me clearance over the stock OEM 0.6 mm headgasket?

Any other recommendations?

 

B18c1
.25 over CTR's
OEM HG
Toda B's

The only way to find out for sure is to clay the motor, but there shouldn't be any issues at all. I ran that exact same setup but with JunIII's and I had no problems.

I also know several people that have had Toda's B's with CTR's and not had any problems with piston to valve clearances...

But again, the only way to be absolutely sure is to clay the motor.

 

yea, i think i may have to, but also buy 1 or two more head gaskets, maybe go to 1.0 mm.

the only other thing as i think about it is that the block was resleeved, but i don't think that should really have effect as the deck to piston relationship seems unchanged and it is a speced flat surface - in other words no "popup" piston arrangement...

any ideas why without the belt on that both the in and ex cams would bind at about +/- 30 degrees as i rotate the cams by their end bolts with a wrench

 

maybe this is where natural interference would develop as there is not a lot of tolerance with clearance in such a setup...would that be the reason that i start to impinge at the ~30 degrees of rotation and that this would be as expected??

 

I wouldnt worrie about piston to valve clearance you should be fine, but one thing you should know is that the ctr piston has a slightly different wrist pin location, which puts the piston about .020 above the deck with a b16 block which is not a problem if your using a stock b16(pr3 p73)head, but if your using a gsr(p72)head or b16 w/welded chambers it will be very close to smacking the head. pistons .020 above the deck w/oem head gasket .030 leaves you with .010 clearance (cold).
But i never tryed ctr pistons in a 18c block it might be fine. But if it does stick out of the deck, just add that number to your head gasket thickness. but thats just me.

 

yea, i think that i will be ok and that the answer is that interference btwn valve and piston will occur past about 20-25 degrees of rotation with the piston 1 at TDC (when turning the cams without t- belt on)