push rods on gx 390

Kart43

Member
When assembled the push rod should allow the tip of the rocker arm to make contact at the center of the valve tip. Generally the rocker arm should be parallel with the valve cover sealing surface.
 

truck

New member
There is no correct answer.....how much is head shaved, how much is block decked, what is base circle of camshaft, how long are your lifters, how long are the valves, how much rocker height will you need.......this question can only be answered by the engine builder, if that's you then you have a lot of geometry to do.....not hard just have to mock up and measure.....I use manton 1/4" pushrod kits he puts one tip in pushrod for you then you cut to length you need, then knock in the other tip.......you will need to know a rough length estimate.....
 
Kart43's answer is the correct one. I originally was going to say "whatever length it takes to get the right rocker geometry," which is about as specific as the question.
 

fredjones

New member
there is no correct answer.....how much is head shaved, how much is block decked, what is base circle of camshaft, how long are your lifters, how long are the valves, how much rocker height will you need.......this question can only be answered by the engine builder, if that's you then you have a lot of geometry to do.....not hard just have to mock up and measure.....i use manton 1/4" pushrod kits he puts one tip in pushrod for you then you cut to length you need, then knock in the other tip.......you will need to know a rough length estimate.....



yep!
 

truck

New member
How do you mean? So there is maximum thread engagement or so there is maximum adjuster sticking out on the pushrod side of the rocker?

if you do not screw adjuster bolt until it sticks out the bottom, the pushrod can get stuck in threaded hole.......and that will ruin the rocker......
 

Kart43

Member
if you do not screw adjuster bolt until it sticks out the bottom, the pushrod can get stuck in threaded hole.......and that will ruin the rocker......

This reply has me totally lost, where on the clone is there an adjuster bolt? What bottom does this elusive bolt have to stick out of? What threaded hole will the push rod get stuck in?

It seems like such a simple question, assemble engine, adjust rockers so they are very close to parallel to the valve cover sealing surface, measure from indent in tappet to indent in rocker arm, if you need simple instructions how to do this ask.
 
This is how the conversation went:

Also make sure that the rocker arm adjusters are threaded completely into the aluminum rocker (if you are using them.)

How do you mean? So there is maximum thread engagement or so there is maximum adjuster sticking out on the pushrod side of the rocker?

if you do not screw adjuster bolt until it sticks out the bottom, the pushrod can get stuck in threaded hole.......and that will ruin the rocker......
 
I think, (and let me assure you "think" is used cautiously here) I know what is being said. If you use rockers like Raceseng roller rockers (and others) the adjuster to set the lash is a threaded screw on top of the push rod. Champions are on top the valve. If while adjusting the lash, the screw does not "stick" out the bottom of the rocker so as to have the pushrod "cup" set on the pushrod below the level of the aluminum rocker, you could have the push rod "bang" into the threads of the adjuster and ruin them. In the case that I so terribly described, a shorter pushrod would be needed OR spacers under the rocker were it bolts to the head. Depends on the geometry. Again, I apologize if this is not what is being described. Good luck to all.
 

Kart43

Member
I only assumed it is on the Honda forum and referring to the GX390, we would be using the Honda rockers. As the OP never gave the details of what he was using.
 

CarlsonMotorsports

Site Supporter
Likewise, since the OP was asking about the length of pushrods that he needed, I felt that he had done some modifications (deck height, head milled, aftermarket valves or rockers??) that would change the required length of the push rods thus prompting his question. Sorry if my answer was not clear or misleading -- only trying to help.

Brian
 
Iam using billet steel rockers from NR racing and longer valves from Parsons its been quit the challenge to get things right and I still dont have it right
 
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