I know theres a million of these out there, but I can only seem to find a few. If anyone know a previous post or can help me please do.

Ok, so I have a set of HS 1.8 rockers, and a set of new Cnc LS1 210cc/64cc heads with dual springs capable of .680 lift. Im going to install the on a stock 4.8 iron block. No cam, nothing else done. My question is, by moving from a 1.7 rocker, should my pushrod size go down from 7.400? Or would it go up? Im going to order a rod measuring tool from compcams because I didn't think about it in the first place like an idiot.

I understand this combo and route might grind a gear with some of you, but I am doing an experiment with the stock bottom end. lol.

 

Usually the length stays the same, but some companies do require a shorter pushrod. Your best bet is to measure as you mentioned to make sure. $20 for the length checker tool is well worth insuring that your valve train is setup properly.

 

Ok thanks, just trying to see if anyone has done it before since I'm not changing the cam.

 

If the heads aren't milled then the 7.4's should be fine with a hydraulic lifter

 

I am running stock push rods with my 1.8 HS rockers

 

What you mean by milled? like if its been decked?

 

thanks, Im hoping to use stock size and be fine, I ordered the 7.4 size at the same time i got the measuring tool, so hopefully i don't have to send them back

 

You can always check your lifter preload if you're concerned about it

 

Is that 1 1/4- 1 3/4 turn past the 22lbs? Like I set it at 22lbs, then after its at 22lbs I turn it more?

 

No you have to spin the pushrod with your fingers while tightening the rockers down until you feel drag on the pushrod--- no clearance between the rocker and pushrod.

Once you feel a drag (zero lash) then you torque the rocker down to 22 ft/lbs and see how many revolutions it takes

I like 1/4-1/2 a turn ideally but you can go over one full turn generally.

 

Ah, so zero lash, the count the turns. So 1/4-3/4 is what im aiming for? Anything over that is bad?

 

Best to spend $20 on the tool rather than counting turns. Turn counting is not linear.