Mick wrote:
The Doc is all over this like a rash and will drop some figures in with a bit of luck later, but it seems standard rockers (including Cooper S forged type) are unreliable in their exact ratio and don't EVER make 1.3:1.
Aftermarket rockers promise a better known ratio with 1.5:1's promise a little more valve lift without having to change your cam shaft out.
Fixed for ya Mick.
I tested all the rockers (except 1275 pressed steel) with a new RE13 cam, and a 12G1316 (1275) head.
From file:
22/7/07 Checked valve lift- 12G1316 head fully assembled.
RE13 cam (.290" lobe lift), stock pushrod, valve clearance .016”:
Lift at #1 inlet valve-
S forged rockers 0.321”(1.16:1)
A+ sintered rockers 0.327”(1.18:1)
998 Deluxe rockers, cast iron posts 0.337”(1.21:1)
998 Deluxe rockers, A+ sintered posts (are 0.3mm shorter than CI) 0.339”(1.22:1)
998 Deluxe rockers, cast posts lowered 0.6mm, offset bushed 1.0mm. 0.359”(1.29:1)
998 Deluxe rockers, cast posts lowered 0.6mm, offset bushed 1.1mm 0.365”(1.31:1)
1275 pressed steel rockers, offset bushed .044” (1.1mm) 0.376”(1.35:1)
Corolla rockers, late `sintered rocker’ type posts, shaft offset 3.9mm 0.402”(1.44:1)
I used to offset bush the pressed steel ones, that gave 1.31:1. However you can buy new 1.3 Minisport roller ones now cheaper than I can do them...
Same story with Corolla 1.44 ones I made, Minisport 1.5 rollers or Minispares 1.5 forged ones are cheaper now.
_________________
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.
