Whats the measurement for preload?
01-15-2006, 09:04 PM
#1
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Whats the measurement for preload? Every quarter turn past zero lash equals ? amount of preload. Search aint being too freindly on this one.
01-16-2006, 12:39 AM
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LSxGuy widda 9sec Mustang
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Its not a good way, but it works when a dial indicator is not present. I believe each 1/4 turn is about .012"-.014" with the stock m8 rocker bolt. Its not exact, but its close enough to tell if you have too little or way too much.
01-16-2006, 01:07 AM
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Originally Posted by PREDATOR-Z
That is not the way to measure preload Cat 
And it depends on what rockers you are using.
And it depends on what rockers you are using.
Pred, I know that, but I just wanted to know the "rule of thumb" ppl go off. I am using stock rockers, and really do need to get a dial indicator. But, might be swapping over to some Vinci/Crane rockers soon. Not sure yet, but really dont want to **** the bearings everywhere with my new engine.
Joseph, thanks. A "guesstimate" is all thats needed for a friend.
01-16-2006, 01:26 AM
#5
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Stock rockers do not adjust so 22>24 lbs it is with the TDC method, rotate 2 revolutions and retorque.
If it is p-rod length you're checking use a p-rod meter tool. In general if it take more than 1 full revolution past 0 lash to trq to 22 lbs then your p-rods are to short.
With non adjustables you'll have different preload on every lifter (by a small margin) so the turn method is pointless and an absolute waiste of time IMO.
Preload has to be measured hot since lifters would have bled down during swap and by no means will register any CORRECT figures or estimates.
If it is p-rod length you're checking use a p-rod meter tool. In general if it take more than 1 full revolution past 0 lash to trq to 22 lbs then your p-rods are to short.
With non adjustables you'll have different preload on every lifter (by a small margin) so the turn method is pointless and an absolute waiste of time IMO.
Preload has to be measured hot since lifters would have bled down during swap and by no means will register any CORRECT figures or estimates.
01-16-2006, 02:44 AM
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Pred, I am talking ballpark, for those ppl w/o the dial indicator/adj prod and tester valvespring. The method above, and here below, will get you in the ballpark, for quick reference if you will.
Warm engine. loosen ex/int rocker. set zero lash. count turns to 22lbs. rotate engine and recheck (add turn counting if appropriate). This should get you a ballpark, which is all that is needed sometimes.
e.g. if my Morels say to use .030" +/-.005, and engine builder says .100" +/- .010". I count 1/2 turn from zero lash to 22's, then I either way I am short some preload, cause that would be about .024-.028". In this case a longer prod would be recommended.
Warm engine. loosen ex/int rocker. set zero lash. count turns to 22lbs. rotate engine and recheck (add turn counting if appropriate). This should get you a ballpark, which is all that is needed sometimes.
e.g. if my Morels say to use .030" +/-.005, and engine builder says .100" +/- .010". I count 1/2 turn from zero lash to 22's, then I either way I am short some preload, cause that would be about .024-.028". In this case a longer prod would be recommended.
