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

[bobhasissues]

Stu,

Nobody will try to help you if you continue with your argumentative attitude.

MY Raby cam card shows the peak cam lift and peak valve lift based on 1.3 rocker ratios. I would think your card shows the same.

All factory Type IV lifters regardless of 1.7, 1.8 or 2.0 have a 1.3 ratio. Go with 1.3, stop trying to re-evaluate a known value.

Jake's article explains that shims and pushrod lengths will affect total lift.
Look at the value for peak lift valve on your cam card and shoot for that.

[stugray]

Stu,

Nobody will try to help you if you continue with your argumentative attitude.

MY Raby cam card shows the peak cam lift and peak valve lift based on 1.3 rocker ratios. I would think your card shows the same.

All factory Type IV lifters regardless of 1.7, 1.8 or 2.0 have a 1.3 ratio. Go with 1.3, stop trying to re-evaluate a known value.

Jake's article explains that shims and pushrod lengths will affect total lift.
Look at the value for peak lift valve on your cam card and shoot for that.

Bob, now that we have established that these rockers tend to be 1.4, I suggest you re-evaluate your statement above. I have now measured 5 sets of 1.8L Intake rockers and found them to be almost exactly 1.4 Ratio. So should I just ignore reality or "stop trying to re-evaluate a known value"? What is that "known" value again?

Stu

[bobhasissues]

Bob, now that we have established that these rockers tend to be 1.4, I suggest you re-evaluate your statement above. I have now measured 5 sets of 1.8L Intake rockers and found them to be almost exactly 1.4 Ratio. So should I just ignore reality or "stop trying to re-evaluate a known value"? What is that "known" value again?

Stu,
Here are the known values:
1) You are a mentally ill idiot who insists on having the last word. I don't think you have established a thing other than you are an asshole. A lot of people tried to politely point that out to you in your Raby rant thread but nobody seems to have gotten through to you.
2) You will build a grenade, that's why I follow this thread.
3) Nobody really wants you to fail (but you are such a douche I can't wait for it)


The geometry of your set-up will effect your ratio. You have already stated that shimming the rockers has changed your ratio. Have you tried shortening your pushrods? Pushrod length will also have an effect on the ratio because you will have to re-adjust the swivel foot to compensate for the shortened pushrod which will change the centerline of the rocker and effect the ratio. Also, you've read it in Raby's instructions and it has been repeated here, at 50% of whatever your lift is you need to make sure your adjusters and valves are in a straight line, otherwise the geometry is wrong and everything else you are doing is a waste of time.