pushrod selection
Thread Starter
Racer
Joined: Aug 2007
Posts: 305
Likes: 1
From: DRAYTON VALLEY ALBERTA
pushrod selection
Ok i need to know do i need to account for preload when checking pushrod length, if so what figure do i work with. I shimmed my hydrolic lifters with washers and checked like that. Is there another way i should do it. Please someone point me in the right direction. Also how do i know where my rockers should be sitting on my studs, I know my pushrod length will determine that but is there a too low or high spot.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
When valve train geometry is correct the rocker tip will roll back & forth along a path that's centered in the center of the valve tip.
So long as the rocker moves without friction it's position up/down on the stud is not important.
You can buy a pushrod of adjustable length for determining correct pushrod length.
Why are you concerned with this topic??
So long as the rocker moves without friction it's position up/down on the stud is not important.
You can buy a pushrod of adjustable length for determining correct pushrod length.
Why are you concerned with this topic??
Thread Starter
Racer
Joined: Aug 2007
Posts: 305
Likes: 1
From: DRAYTON VALLEY ALBERTA
i just did trick flow heads a comp cams cam 1.6 rr a first intake and may othes and now i need to determine the push rod length so im wondering do i need to account for preload on the lifters. many people say to go with a solid lifter and or shim up the hydrolic one to determine the length. so what im asking is can someone give me exact no detail left out on how to determine proper push rod length. there is a pile of links ive found but none of them have stated what to do with the preload on hydrolic lifters. and my concern with the rocker arm is that it can be anywhere on the stud but how do you know if it is too high up on the stud with pushrods in place or too low .
Drifting
Joined: Dec 2005
Posts: 1,313
Likes: 2
From: High Ridge Missouri
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
...my concern with the rocker arm is that it can be anywhere on the stud but how do you know if it is too high up on the stud with pushrods in place or too low .
The rocker will ride where it must to give the proper preload for the pushrod length chosen.
I'm thinking that, even with the adjustable pushrod, you set preload and then watch the rocker tip travel across the valve tip as you manually rotate the crankshaft. So the preload here would be the same as for the final valve lash adjustment.
Instructor
Joined: Dec 2005
Posts: 102
Likes: 0
From: Carnegie PA
Yes, watch the rocker travel across the top of the valve stem but there is a way to see the actual pattern. "paint" the end of the valve stem with a magic marker. Assembly the rocker arm and manually rotate the engine a few times. Remove the rocker arm and you will see a definite mark on top of the valve stem where the rocker contacts it. Of course this mark should be reasonably centered on the stem. Adjust the push rod to center the mark.
Thread Starter
Racer
Joined: Aug 2007
Posts: 305
Likes: 1
From: DRAYTON VALLEY ALBERTA
ok i got the whole part about how to measure for length. the ? i am asking is do i need to shim the lifter to make it a solid lifter or should i be doing this with a normal hydrolic roler lifter. i have heard both stories now and i want to get this right.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
For the most accurate results, substitute in a solid lifter for the hydraulic lifer to keep the valve spring from depressing the plunger. Alternately, you can check for proper geometry with light, "checking springs" in the head. It is an easy matter to factor in the preload distance for push rod length, where necessary.
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