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..... What do I set valve lash at when using 1.65/1.70 rockers on a cam that was ground with 1.50's intended ? ... Do I multiply the lash by the ratio ? ... Or do I use the same lash no matter the rocker ratio ? .....
 

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valve lash * (new rocker arm ratio / old rocker arm ratio)

if your valve lash is 0.020"

► 0.020" * (1.7 / 1.5) = 0.0227"

Stan
 

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Stan's correct.

To make it easy to remember.
Divide the Old Lash by the Old Rocker Ratio, then multiply by the New Rocker Ratio to get the New Lash.

Example:
Cam card says to run .018" lash with 1.5 rockers, but you want to run 1.7 rockers.
.018" / 1.5 = .012"
.012" x 1.7 = .0204"
New Lash is .020"
 

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Thanks for bringing that up, I had never thought about it. Good post.
 

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Stan's correct.

To make it easy to remember.
Divide the Old Lash by the Old Rocker Ratio, then multiply by the New Rocker Ratio to get the New Lash.

Example:
Cam card says to run .018" lash with 1.5 rockers, but you want to run 1.7 rockers.
.018" / 1.5 = .012"
.012" x 1.7 = .0204"
New Lash is .020"

Is that because of the ramps for clearance or just to keep the cam at correct timing . ?????
 

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Go Phuck youself
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Just remember there are three parameters. The Cam has a Ramp(1), the Valve has Lash(2) and the Rocker Arm Ratio(3), if any, is the relationship between the Ramp and Lash.

Lash = .016"
------------------Rocker Ratio
Ramp = .010"
How close to zero lash can you push a solid roller lifter valve train to play around with timing? to look at what the motor is liking better in timing? The days of .030 valve lash is over if you want your valve train to live along time that's for sure.
 

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How close to zero lash can you push a solid roller lifter valve train to play around with timing? to look at what the motor is liking better in timing? The days of .030 valve lash is over if you want your valve train to live along time that's for sure.
As tight as you want. For testing, there's no reason you can't go as low as .001" cold(assuming the lash increases with temp.).
 

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As tight as you want. For testing, there's no reason you can't go as low as .001" cold(assuming the lash increases with temp.).
OK Thank You. I learned on a 1955 ford 292 312 which is a soild lifter cam valve train. I learned to adjust them while the engine was running adjusting them. I think the lash was .012 and until you aquire the feel for slipping that feelers gauge thru and the temp. is correct it was easy to get them to tight and cause the valve to stay open on the seat just enough to cause leakage either way and engine would start shacking LOL. Then I learned the cycles of the internal combustion engine and understood the system. I was 11 back then and off I went. So it does get tricky when you start getting closer to .010 of lash, it becomes a art at learning the feel and how temp. makes a big diff. Leaving the valve covers off to long even while its running makes a huge change.

FOOD FOR THOUGHT. Douglas
 
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