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]

Two more questions:

1 - When some of you have had to shim the rockers, how much is typical.
I want to know what assortment of shims to preorder before the final measurements.
I have shimmed them out to 0.200 using washers and only see a marginal reduction in rocker ratio. However the swivel foot adjusters appear to prefer at least a 0.050 spacing for good clearance.

2 - Who has a good selection of rocker shims?


And nathansnathan

Also, the further out the adjusters are the more likely you are to hit the covers.

How is that possible? Regardless of where the adusters are set, that only changes the position of the rocker up&down on the adjuster. The distance from the top of the valve plus the length of the adjuster foot is fixed and does not change as you adjust them. The absolute maximum is when the valve is closed, so that number can never change even if you shim the rockers.

Confused.

Stu

[wndsrfr]

2 - Who has a good selection of rocker shims?

EMW at Hawthorne has a nice set of shims cheap....
http://www.europeanmotorworks.com/pvw/054-...ometry+Shim+Kit

I used 'em to get my adjusters in-line with the valve stem at half lift..

You've got a good point about shimming not moving the top end of the adjusters up since they're seated on the valve stem +or- lash amount....but you do slightly change the arc of rotation & might bring them closer to the slope of the valve cover...or if you somehow got a thinner valve cover gasket also! Chris's idea of cutting them off seems best....less weight where it really really counts!