small blk rocker geometry

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416stroker

416stroker

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Guys,

I need some input here on how high is to high to shim/raise a rocker shaft in order to get good rocker geometry. Here's my issue. I'm running Eddie heads with Hughes 1.5 rocker arm kit. My cam is a Hughes hydraulic roller with .533/540 lift. When I first checked the tip wear pattern I was way back on the tip towards the intake side. In order to get anywhere close to the middle of the valve tip, I had to shim up the shaft .120. I checked the wear pattern and it still looks like I need to go higher! Is that possible?? Is there a limit on how high you can go? I'll try to attach a couple of pics for you to look at.
 
Forgot to mention too that in the first picture the valve on the right looks to me to have to two scrub patterns. Almost makes an X if you look close. What's up with that? The valves aren't supposed to be turning are they?
 
Have you check the install height(stem installed height?)

.120" shim on the rocker shaft seam like a lot.

I'm still trying to get the full grasp of valve geometry stuff my self so i'm not much help beyond this.
 
416stroker said:
Forgot to mention too that in the first picture the valve on the right looks to me to have to two scrub patterns. Almost makes an X if you look close. What's up with that? The valves aren't supposed to be turning are they?
Click to expand...

Are the valve locks a singe "grove" double or triple grove lock?

If it's a triple lock, they were designed to rotate.

could just be the lock turned before it seated completely into the retainer.
 
416stroker said:
The locks are single groove.

The installed spring height is 1.800
Click to expand...

Spring height or valve stem height ?

spring height won't affect geometry, unless the rocker is hitting the retainer.
 
According to my parts list the valve spring height is 1.800 installed

I'm not totally sure of the valve stem height. They're Eddie heads.
 
I understand the how valve geometry works on a small block and where you raise or shim the shafts when the roller tip is favoring the intake side to much and when the roller is to the exhaust side to far how you need to look at the pedastles and changing that elevation. I guess I never heard anyone tell of how much is safe to raise the shafts before they can start to become unstable. I know of guys who have went up .050 or maybe .080 but .120 seems out there to me. Maybe not?? Maybe you go as far as you need to with shims to get a good pattern and not worry about it??
 
.120" shim tells me that the valve stems were not ground to proper height aka two long, and requiring you to compensate with the .120 shim.

I can't remember what the valve stem Height Is, but it might be worth a check.

It might be the rocker arm it's self, but i don't thing so. Check the valve stem height first.
 
You're probably right! I still need to go a little more yet on the height but it makes me nervous to think about it!

Thanks for the input guys! I'll let you know what I come up with.
 
Stock springs assembled were 1 5/8 to 1 11/16. Mine are 1.800 which is about .113 difference taller. So with that amount plus like you said about the stems not being machined down to the correct length adds up to .120 and then some. Don't feel like pulling the heads and have the valves reworked if I don't have to. I'll have to do some more research on this and get back to you and let you know what I ended up doing.
 
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