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Rb20 Piston To Valve Clearance

Psymon

By Psymon,
in Engines & Forced Induction

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Psymon Mentor

Psymon

Posted
Posted (edited)

How much lift is it possible to have on an RB20 camshaft before there will be piston to valve clearance issues?

I have a 2nd hand head i'd like to put on my engine with aftermarket cams in it and they seem to have quite a bit more lift than standard cams. I don't want to put it on and crank it over only to end up with bend valves!

Edit: probably should have said that they're standard pistons! :P

Edited by Psymon
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grandmasterb Grand Master

grandmasterb

Posted
Posted

Im running HKS 264's with 9.3 lift with stock springs and there are no issues but have not wound much boost in yet.

Having said that after looking at the clearances i would say that 9.3-9.4 would be the most you could get away with prior to upgrading valve springs. Others will tell you to replace them anyway to be safe but for me it was a matter of $$$'s and curiosity to see if 9.3 was too much.

At the end of the day another RB20 is only $500 which is roughly the same for valve springs and i dont plan on running more than 1.2-1.3bar so will see what happens :)

Psymon Mentor

Psymon

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  • Author
Posted

Well that seems to be the same lift as these cams have so it should be good! :) The valve springs are upgraded so shouldn't be a problem there.

I just wanted to make sure that the extra lift over factory wouldn't cause valves to start hitting pistons!

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