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rocker ratio's
https://www.ausmini.com/forums/viewtopic.php?f=5&t=79040		 Page 1 of 1
Author:  justfanginaround [ Thu Nov 01, 2012 10:24 am ]
Post subject:  rocker ratio's
I'm wondering what the ratio's are for the pressed steel, forged "S" and the sintered rocker arm are.

Just kinda curious.
Author:  drmini in aust [ Thu Nov 01, 2012 10:33 am ]
Post subject: 
A while ago I set up an RE13 cam (.290" lobe lift) in a block, put a 12G940 head on it and tried a bunch of different rockers.
I will dig out the file I wrote shortly, but from memory-
S forged rockers, 1.16:1
Sintered A+ etc rockers, 1.18:1
Pressed steel 850/998/1098 rockers, 1.20 or 1.21:1

None of em got anywhere near the 1.25 that people think they are... :lol:

[edit] Pressed steel rockers with my 0.044" offset bushes, got 1.31:1.
1275 oval pad pressed steel rockers with these same bushes got 1.35:1.
Both tested on the same head/block/cam setup.
Author:  justfanginaround [ Thu Nov 01, 2012 10:40 am ]
Post subject: 
thanks doc for the very quick reply :)
Author:  drmini in aust [ Thu Nov 01, 2012 11:08 am ]
Post subject: 
Here's the lift figures, the head was a 12G1316 (1275 smog head)not a 940 as I said.

Rocker ratio = (valve lift " + .016" clearance)/.290" lobe lift

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”
A+ sintered rockers 0.327”
998 Deluxe rockers, cast iron posts 0.337”
998 Deluxe rockers, A+ sintered posts (are 0.3mm shorter than CI) 0.339”
998 Deluxe rockers, cast posts lowered 0.6mm, offset bushed 1.0mm. 0.359”
998 Deluxe rockers, cast posts lowered 0.6mm, offset bushed 1.1mm 0.365”(1.31:1)

Toyota Corolla rockers, late `sintered rocker’ type posts, shaft offset 3.9mm 0.402”(1.44:1)
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