Does this wear pattern look ok? This is the first time I've done a valvetrain setup, and am looking for opinions. The wear pattern seems to be just off center. Is it close enough where I don't need to change pushrod length?



If the image doesn't work, you can see the pics here.

Thanks,
Thomas.

 

Tom, you want the travel to be from over center thru center to over center on the other side.
Use this page from Comp cams to double check the length of the push rods
http://www.compcams.com/Technical/Cu...ML/306-307.asp
You should check the roller to be sure they are moving correctly also.
If you can't see the travel you can use a sharpie on the valve.

 

I would want the pattern offset by about that amount but in the opposite direction. With what you have, the point where the rocker contact is directly over the center of the valve is at a fairly low lift. You want the point where it is over the center to be at 2/3 to 3/4 of the full lift so that the highest spring pressures are concentrated over the center of the valve rather than the edge. My guess is that a .050" shorter pushrod would put you in the ballpark. If you are going to be changing anything (valve job, rockers, cam) wait until you get everything back together before you check the pattern because it will change. You can dykem the head of the valve to see the pattern.

Jim

 

I did use a sharpie on the valve stem before checking the pattern and I have the whole valvetrain setup with the components I am using: Scorpion 1.7 RR, 7/16 ARP studs, GM guideplates, comp 918 springs, and comp 7.2" hardened pushrods.

Doesn't the roller move closer to the intake as the valve opens? If so, at full open, it looks like the roller is just a bit past center, on the intake side. To move it even closer to the intake, I thought a longer pushrod would be needed, not a shorter one?

Thanks for the input guys,
Thomas.

 

Ya need it to start on the intake side of center,be at center at 50% lift,go past center at 100% lift and return to the intake side of center. It should be as narrow a line as possible.
Looks like ya need a shorter PR and that will bring it back toward the intake and shorten the sweep(narrow the line also).
Everybody does it different,but the line needs to be as close to center as possible and as narrow as possible. Get a pair of adjustable PR's and keep adding or subtracting until ya get it looking good. Ya can get some Persian blueing at Lowe's in the paint dept. It marks well and don't dry out.

 

Yeah I'd get a PR length checker and try .050 shorter.

 

You can light the area from behind and watch how the contact point moves across the valve head as you open the valve. If you have hydraulic lifters you will probably bleed them down and the max lift point will be up to .100" lower than it would be running. That means that the contact point will actually move farther toward the exhaust side than what you see. Like mentioned above, get an adjustable pushrod and play with it until you get it right.

Jim

 

Ok, I'll definitely do that. So a shorter pushrod will move the pattern closer to the intake, and a longer will move it closer to the exhaust?

And the closer to center it gets, the narrower the pattern becomes?

Sorry for the basic questions here ... I really appreciate the help.

Thomas.

 

Mine ended up looking pretty much the same length but it moved back and forth with pushrod length. I tried to concentrate the higher lift portion of the pattern over the center of the stem so the higher spring forces would be concentrated over the centerline rather than toward the edge to minimize stem/guide wear.

 

A lot of this depends on the angle ya start at. The stock angle is about 90* to the valve stem or a little down on the PR end.This is where ya start.
Just adjust the checker till the pattern looks right,then measure it and find the closest PR to it. Don't worry about .050 shorter or longer till ya get the pattern right 'cause it will be what it will be.

 

thats what I would do as well.... it looks like .050" less would be about right.

Bret