Corolla rockers are too big for a smallbore- unless it's a racecar, 1.3 ones is the way to go.
Fitting and reaming offset bushes is a PITA- I did it years ago.
It's very hard to get the offset in the same place on each rocker.
I'm doing some 1.31:1 rockers right now for Wombat-
I press solid LG2 bushes into pressed steel rockers, then offset bore them by 1.1mm to finished size in the mill.
This way, they are all offset identical and I don't need to ream them, either.
I fine bore them to have 1/2 a thou (.0005") clearance on the shaft.
Then I drill out the stud holes in the standard rocker posts as Vizard says, you then push the rockers back when bolting down.
Wombat's are the 3rd set I've done.
Pics of my 1st set with 1275 head (going on the 1132 Moke)-
<edit> Here are the results I obtained from different rockers last year.
22/7/07 Checked valve lift- 12G1316 head fully assembled.
RE13 cam, stock pushrod, valve clearance .016”:
Lift at #1 inlet valve-
S forged rockers 0.321” lift
A+ sintered rockers 0.327” lift
998 Deluxe rockers, cast iron posts 0.337” lift
998 Deluxe rockers, A+ sintered posts 0.339” lift
998 Deluxe rockers, cast posts lowered 0.6mm, rockers offset bushed 1.0mm, 0.359” lift
998 Deluxe rockers, cast posts lowered 0.6mm, rocckers offset bushed 1.1mm, 0.365” lift (1.31:1)
Corolla rockers, late `sintered rocker’ type posts with shaft offset 3.9mm, 0.402” lift (1.44:1)
There is probably a few thou more valve lift hiding there if I play with pushrod length- these figures were using a stock height 998 block and pushrods.
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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.
