Figuring proper pushrod length

[Jamee]

Hello, building up a 302. I'm running a 92 mustang stock roller cam, 351w heads, and I'm trying to figure out if my stock pushrods will work or not. The stock length rods are 6.25, and the reason I don't believe they're the proper ones is because there's still play between the pushrod and rocker. I ordered a pushrod length tester and I found 6.4 seems to work well with little play. I understand (very little) that the pushrod's length cannot be too long to mess up the preload. Could anyone give me their opinion of the situation? I'm using stock 351w rockers btw

 

[revhead347]

Are these pedastal mount rockers or are they adjustable? Generally if the pushrod is the wrong length, it messes up the valve guides.

Kurt

 

[Jamee]

pedastal mount

 

[revhead347]

Ok. There are a couple ways of doing this, and there are some tutorials on the internet. You can basically do it with your pushrod checking tool and a magic marker. Take the magic marker, and mark the top of the valve with a thick layer of markerage. Then set the pushrod tool at a specific length and put the valvetrain together. Spin the motor around, and take the rocker back off. The head of the rocker is going to rub the markerage off in a line on the top of the valve. You want that line to be at the center of the valve. Each turn of the pushrod tool is a specific change in length. Usually 1/10th of an inch. So you don't have to measure the pushrod tool each time you set it. Just keep track of how many revolutions you turn it. And you have my permission to contact Webster, because I'm pretty sure I invented the word "markerage."

Kurt

 

[Jamee]

Ok. There are a couple ways of doing this, and there are some tutorials on the internet. You can basically do it with your pushrod checking tool and a magic marker. Take the magic marker, and mark the top of the valve with a thick layer of markerage. Then set the pushrod tool at a specific length and put the valvetrain together. Spin the motor around, and take the rocker back off. The head of the rocker is going to rub the markerage off in a line on the top of the valve. You want that line to be at the center of the valve. Each turn of the pushrod tool is a specific change in length. Usually 1/10th of an inch. So you don't have to measure the pushrod tool each time you set it. Just keep track of how many revolutions you turn it. And you have my permission to contact Webster, because I'm pretty sure I invented the word "markerage."

Kurt

I think that method is only effective for roller tip rockers, I've tried it with mine and there's no mark left over... and yeah I have a comp cams adjustable checker with .050 interval rotation

 

[revhead347]

Well shoot. I've never checked pushrod length without roller rockers.

Kurt

 

[Jamee]

Well shoot. I've never checked pushrod length without roller rockers.

Kurt

yeah :-/
lol