What rocker arm ratios do people see? Options

[stugray]

I am adjusting the valve geometry while putting in a Raby 9700 cam and I am seeing .38 on the exhaust cam lift and .496 at the valve (an exh rocker ratio of 1.3) and I have a .39 on the intake with a .546 at the valve ( an int rocker ratio of 1.4) is this what everyone else gets for rocker ratios:

Intake rocker ratio = 1.4
Exhaust rocker ratio = 1.3

These are the 1.7 (1.8?) rockers that accept the 911 swivel feet.
I am using the swivel feet, have modified the rocker faces, adjustable push rod, and zero lash to do the meaurements.

Do those rocker ratios look like stock?

I want to take 50 thousandths off the Combustion chambers to increase the CR, but my measurements say I wont have enough clearance on the Intake valve once I shave off 50 thousandths.

I only have ~0.075 clearance now from the piston to the Int valve as it is with a deck of 0.030 and everything else (crank & rods) stock - flat top 96mm pistons.

That Intake valve travel of ~0.55 looks huge to me. Anyone else care to comment?

Stu

[stugray]

Quick bump so racer chris doesnt forget about me ;-)

Now that I learned that the rocker ratios vary over their whole travel, do I need to check them throughout their entire rotation? My initial measurement of 1.4:1 was with zero shims under the rockers so the swivel feet were only about 1-1/2 turns away from bottoming out. I can get a smaller number for rocker ratio as I shim them out, but only by a total of 0.020.
0.550/0.388 = 1.42 (swivel foot all the way in - no shims)
0.530/0.388 = 1.37 (0.200 shims under rockers)

And I am still bothered by the statement that based on how they are adjusted, they might hit the cover. I still do not see how adjustment can make the tops of the adjusters any taller or shorter when the valve is fully closed (that is when it would hit the cover).

Stu

[ChrisFoley]

Quick bump so racer chris doesnt forget about me ;-)

(IMG:style_emoticons/default/smile.gif)

Pushrod length should be set so valve half lift occurs when the adjuster makes a straight line with the valve stem.
That means the only important part of the rocker motion range is around that point.
I asked for the rocker pictures to see if there was any evidence of modification.
I haven't had a chance to compare any here yet so I can't comment on that.
Shim as necessary to obtain the half lift geometry and swivel foot clearance.
I've never used more than .120 shim thickness.

I always shorten the stem of the adjusters and cut a new screwdriver slot.
Valve covers come in more than one version/shape, and some interfere with the swivel foot stems.