lifter preload
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Elder User
Joined: Jan 2004
Posts: 867
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From: Eastern Pa
lifter preload
I'm checking the preload on my 400 cause the heads had to be cut, about .015 and I put in a Crane powermax cam with Scorpion roller rockers. When I use the .030 shims under the pedestals the preload on some is barely .020 which is the recommended minimum. Without the shims some are over the .060 max recomendation. Whick is the better side to be on the bare minimum or pushing the max.
Lead Driver
Joined: Mar 2004
Posts: 8,922
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.02 is fine But keep in mind that shimming is in some instinances is not going to work as far as rocker arm geometry is concerened at some point you're going to need shorter or longer pushrods. any mfgr. will make push rods for you., in any length, the problem is a lot of machine shops don't control valve stem heights in other words they might grind seats until they clean up - one sunk.03 one sunk .1. and this is where rocker arm geometry problems start , now one push rod has to be longer or shorter than the other, Some companies do make adjustables pushrods. whatever: watch the rocker arm tip sweep the valve stem it should start in at the top and end before it runs off the edge. If it doesn't you'll wear valve guides quickly and maby drop a valve in some instances. anyways if it doesn't look right. Get an adjustible pushrod, set it up so the rocker sweeps the valve stem perfectly and add .02 to the push rod measurement and you've got your length. Im not saying you can't shim, IM saying always check stem & rocker sweep after shimming.
