HumpinSS

iTrader: (1)

But the way hyd lifters work can you really set preload on em. I mean all you are doing is pushing the plunger further down into the bore of the lifter, so what are you actually preloading. Moving the plunger down in the bore can poosibly cause high rpm pump up...

GuitsBoy

iTrader: (4)

With the stockers, no preload setting necessary. Just torque to 22 ft Lbs. On other aftermarket hydraulic lifters, theyre more robust and the spring inside is much stiffer. Setting the preload will push the plunger less distance than with a stock lifter. Conversly, torquing to 22 Ft Lbs may not be enough proload on a stronger aftermarket lifter. Or atleats this is my understanding of it.

DAPSUPRSLO

iTrader: (14)

There is still a range or preload that is acceptable. If everything is stock dimensions then just torqueing down to 22 ft lbs will work. If you change the cam you must note the pre load which is simply the distance/amount of turns from zero lash until 22 ft pounds is reached. 22 ft pounds on 7.4" pushrods will produce less preload then 22 ft pounds on 7.425" pushrods.

ssheets

iTrader: (1)

So with a new cam, new heads and pushrods on stock lifters and rockers how would you go about setting preload?

DAPSUPRSLO

iTrader: (14)

check it by starting at zero lash, see how many turns it takes to get from 0 lash to 22 ft lbs, and then see if the amount of turns falls in the range of acceptable pre load

GuitsBoy

iTrader: (4)

If im understanding him correctly, he's saying that you would have to start with the stock cam and valvetrain. Tighten till you can no longer twist the pushrod with your fingers, as this is zero lash. Then count the degrees to get to 22 ft. lbs. Then when you do your cam and valvetrain swap, tighten rockers to zero lash, and then add the same ammount of turns to the rocker bolts. Thats basically your procedure, DAPSUPRSLO, no?

I dont necessarily agree with that, and this is why. When you start to tighen the rocker bolt, you get to zero lash before the rocker pivot has seated home in its base. By the time youve torqued it to 22 ft. lbs, the rocker is fully seated. Tightening it past 22 ft lbs should not increase the preload on the lifter because the rocker is already bottomed out against the base. further tightening will not bring the rocker further down since its already seated. The same should hold true with an aftermarket cam and pushrods. Once the rockers seat, tightening should not increase preload on the lifters. The only way to change the preload is to measure the differenes in base circles and compensate with different pushrod lengths.

Setting preload on aftermarket lifters really needs to be done using adjustable rockers in order to set the correct preload, otherwise you only get the preload that your pushrod length gives you and thats it.

DAPSUPRSLO

iTrader: (14)

you just mis understood me. We are on the same page. Another way to adjust preload on the stock rocker system is to add shims. Basically with stock rockers you can add shims or change pushrod length to change pre load values. You could also change valve stem length or cut down your rocker pedastools. This is all assuming it does not through off valve train geometry.

Unaffliated Racing

iTrader: (15)

I wish I had time to type a lot and teach class. Most don't undersatnd what is going on. All I can say if you want to know the correct info and proper method...call me.

1-800-365-9145 ext. 558

Thanks,
Brian

ssheets

iTrader: (1)

Now that's cool

HumpinSS

iTrader: (1)

Just got off the phone with him and I have been told that 1/4 is fine for the stock rocker setup

jub jub

I know how you feel bro. Evertime I see that "torque to 22 ft lbs" I cringe!

Stark

iTrader: (25)

<------dials number...
Brian told me the difference between lash and preload, which i didn't know.
He also told me why people buy adjustable roller rockers and the amount of preload they work with. For my cam install, i'll drop in the 7.400 pushrods, torque my stock to 22 ft/lbs, and go about my happy way.
Thanks Brian!