I need help with my Predator push rods

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Oldman35

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Right now I'm building a predator 212cc and the engine is a Hemi. Aside from the necessary flywheel, carb, exhaust mods...
It will have the original head, 1.2 ratio roller rockers, original valves, 26 lb springs, a lift for the valve cover, a mod 2 Dyno cam, and a flat top piston.

My issue is that I have no idea what the push rod length needs to be. I've read in the forum about using playdoe or clay to check for clearance, but I don't even know where to start with the rod length.

Secondary question: Does the valve lash stay the same with the mods I'm doing, or will it change.

Any help is much appreciated, and I'm open to any suggestions or improvements.

Thank you
 
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madtom

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Arc racing suggests 5.260 length rods with a 1.2 ratio rocker. I used this length for my hemi with a cm cam and 1.2 ratio rockers and they were perfect.
.003 valve lash Intake and exhaust for a mod2 cam

You can clearance the inside of the valve cover to clear the rockers. Also to my understanding 26lbs springs is pushing the limits of the stock spring retainers. Personally I'd go with 22lbs springs if you're not upgrading to automotive style retainers and keepers.
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