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]

It is not possible that you are the first to discover the rocker ratio is different than what everyone has believed for 40 years.

Chris - I had three reputable machine heads sit and watch the dial indicator "go-round and round" and measured .520 on two different cylinders and after swapping out the rockers from two different engines. (more than FIVE separate measurements). The cam lift is .368 per Jakes cam card and measurement ....

I have two complete sets of 1.4 Intake rockers. Exhaust rockers measure closer to 1.3.

Stu

[barefoot]

It is not possible that you are the first to discover the rocker ratio is different than what everyone has believed for 40 years.

Chris - I had three reputable machine heads sit and watch the dial indicator "go-round and round" and measured .520 on two different cylinders and after swapping out the rockers from two different engines. (more than FIVE separate measurements). The cam lift is .368 per Jakes cam card and measurement ....

I have two complete sets of 1.4 Intake rockers. Exhaust rockers measure closer to 1.3.

Stu

Just getting into cam selection for my street 2056 w/ carbs.
Curious about rocker ratios, so I made some measurements with my dial calipers
on my late 2.0 rockers with the 10mm adjusters and was surprised to see that the intakes & exhausts are different. Just measuring the rockers alone I got 1.41" from center of pivot bore to center of adjuster screw for both in & ex. However the exhaust had 0.92" from the center of pivot bore to center of pushrod cup while the intake dimension was 1.02"
This results in an exhaust ratio of 1.53 & intake ratio of 1.38.
Note that these are eyeball estimates with the rockers laid horizontal as I did not have height stand or CMM equipment to use.
I don't know what ratio the earlier 1.7 rockers are and if different from intake to exhaust, anyone have this info ??
It seems like folks like to use the early 1.7 rockers fitted with swivel foot 911 adjusters