Good it all fits up for you.
All I can think of is your crank been machined or the plastic calipers aren't accurate. I haven't seen the back of a 2 plus 2 flywheel but it looks like the cast recess is the same as the rb ones. Are you sure it's a 2 plus 2 and not rb?
If it were an rb fwheel it could just be the plastic calipers are just measuring 1mm out.
I was around when we changed over from leaded fuel to unleaded and we had huge problems with ping on out high comp engines. The answer was to pull timing and loose power but we then got into water injection and got all the timing and power back . We just used the vacuum style injection.
It's as simple as putting a 1/8 pipe with a 45deg chamfer on the filter side of the butterfly so it gets no vacuum at idle and as the throttle opens it does .( so the nearest edge of the pipe is 1/8 from the closed plate).
Then run clear vac line to a 1/8 pipe going into water resivour .The pipe needs 5-10 tiny holes where the vac line goes on.
If you put the vac line over all the holes you get max water, sliding it back to uncover more holes lets it suck air and get less water. simple except I suck at explianing. Worked well for me though.
The clear line lets you see the water being sucked.
New 2 z ,
In all my searching so far the RB 20 should have the 81mm crank.
They do have the same bolt pattern , so it's possible you are just pulling the flywheel up against the step.
I strongly recomend you check , as it will cause big problems if i'm right.
Starter works well, quiet, enguages nicely, I don't forsee any problems.
I will post again after some racing.
If anyone has the flywheel hub sizes for RB20, RB26, RB30 , Please post them up.
L series 80mm
RB25 81mm
The box is in again, the chamfer fixed the clearance issue.
I put the slave cyl on and found the bolts a bit long , so they clipped the pressure plate. Found some the right length , problem solved.
Clutch travel looks good and has a bit of free play, looking good so far..
For some reason the vidio dosen't work.
I put my box back in and the pressure plate just touches the bellhousing above the starter hole.
Will post when fixed, just a small grind on the corner back to 45 deg and should be fine.
Could just be the clutch I got , as others don't have this problem.
I still haven't put the box in, Had to go to hospital for back injections but will post soon.
New 2 z, I'm surprised the flywheel fitted . The rb20 must have the smaller crank hub or the L flywheel would not have gone on. Good to know though as I searched and got the impression all the twincams and the rb30 were the same.
If anyone knows the rear crank boss dia for all the motors for sure, the info would be appreciated
The clutch I get this way for $210.00 is at least as good as a $400.00 custom one.
Flywheel free , Holfords 6 puck 240mm $165.00 and $45.00 for the rings, I got 3 done nearly the same price.