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Discussion Starter · #1 ·
What is the formula for figuring out the valve lash with the roller rockers? I see here at the sight people have many different setting from 10 intake and 12 exhaust all the way up to 20. How do you figure out the definitive setting?

In my case I have a 1.9 bored to 2.4 with the 30 over Chevy pistons and Chevy valves of 1.84 and 1.50. The head has been ported by Rodgers and should be done as close to correct as these things are. The cam I have is 430 lift 270 dur @50 with 108 sep.

Right now for the engine break in the valves are at 10 and 12 set cold in the machine shop and the engine has run about 20 min…

So now when retorque the head and do the valves where do I set it?


Thank you,

Calvin
 

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Senior Contributor
Joined
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499 Posts
Discussion Starter · #2 ·
wells some formula's but not the one i need all i can find is check cam card and the cam builder is clossed for the weekend. So I will try 12 on intake and 14 on exhaust.

D. GROSS VALVE LIFT - The total cam lift multiplied by the rocker arm ratio. (CL .280" X RAR 1.5 = GVL .420")


our roller rockers have a ratio of 1.557


NET VALVE LIFT - Gross valve lift minus the valve lash setting for a mechanical camshaft. Net valve lift is not specified for hydraulic camshafts. (GVL .395" - VL .012" = NVL .383")


TIP: Valve Lash Tuning. Setting valve lash is an important part of the tuning process for maximum engine performance. Use the recommended lash setting on Cam Card as a starting point. However, lash may require some tweaking for your engine combination. The results of setting lash to a larger value effectively "Shortens" the Camshaft. This is because the Lifter has to move a greater distance to take up the lash before the valve begins to move. By "Tightening" the lash to a smaller value, you effectively make the Cam seem Larger. Remember to use your Cam Card as baseline and tweak as necessary for your engine combo. Tuning your lash is a good tool to determine if your engine combo actually needs a larger or smaller cam!
 
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