Does anyone know what the clearance should be between the rocker tip and valve tip on a solid lifter motor? It's non roller if that matters. I've heard between .010-.035. Thanks.

 

Depends on what the cam manufacturer recommends. It will be listed on the cam card.

0.018 to 0.030 is a ballpark figure and there's always a larger gap on the exhaust valves. You can play with valve lash slightly to see if an engine likes more or less lift but you shouldn't go more than 2 or 3 thou in either direction from what's recommended.

 

I didn't even know it was a solid cam until after I took the heads off and have tried to adjust the valve like on a hydrolic. So I have no idea what's recommended for this cam. This is my 1st time w/ a solid. Thanks.

 

Without know what cam it is there's no telling what the adjustment is. A quick look through the CompCams catalog has many settings, providing it's even a Comp cam.

int 0.026 ex 0.028
int 0.018 ex 0.020
int 0.020 ex 0.022

 

I'm starting to think that it would be better to just convert it to a hydrolic roller. Screw all this complicated stuff, lol.

 

So what kind of power losses and damage would occur if the motor was ran at .045 or so and the cam card recommended .023 intake and exhaust?

Dave

 

You would have 0.022" less lift and the valve train geometry would be off since the rocker would have to travel that extra 0.022" before it contacted the valve.

That's part of the problem that most people don't realize with solid cams. The gross advertized lift is at zero lash. Since all solid cams require a small amount of valve lash, that distance is lost in the total lift. A hydraulic cam's lift is the actual amount of lift that will be seen by the valve since a hydraulic cam runs at zero lash.

I'll use my own for example.
Total lift is 0.638 intake and exhaust.
Lash is 0.028 in and .030 ex.
Lobe lift is 0.375
1.7 rocker ratio.

The roller cam going into my new engine will be around 0.750 lift

If set to zero lash like a hydraulic cam the 0.375 lobe lift times the 1.7 rocker ratio gives 0.6375 total lift. Since the intake rocker has a 0.028 lash, the rocker isn't touching the valve when the lifter is on the base circle of the cam. The lobe lift is calculated the distance between the base circle and the amount of lift off the base circle.

Since my intake is lashed at 0.028, my actual valve lift is only 0.6095. By decreasing the valve lash to 0.022 I could increase the valve lift to 0.6155 however solid cams need a certain amount of lash because of how the ramp design is and how the solid lifter rides up the ramp. Also by tightening the lash you increase the duration slightly since the valve will now open sooner and close later. Playing with valve lash like that is a good way to determine if the proper cam has been selected but it should never be run like that. A camshaft is designed for a specific lash setting.

Since you want to pull the cam and install a hydraulic one in, you're going to decide on pulling the timing cover anyway. When you pull the cam gear, you'll see the grind numbers on the end of the cam. From those numbers, you could determine who's cam it is and get the cam card for it.

You could also throw a degree wheel on the engine and use a dial gauge to make a cam card. Then compare it to other cam cards to see which one is closest to your results. Not always a 100% way of doing it since different companys have similar grinds.

 

I suppse all of those lash numbers are for a hot engine, right? I read to set them all while the motor was hot but if it's cold subtract .006 for aluminumheads/iron block. I gapped them at .016 intake and .018 exhaust, which hot should be around .022/.024

 

A room temperature engine is considered a "hot" engine when setting valves.

 

Daniel- you've got 'em close enough for government work. I woulda done them at .020 in the absence of a cam card to give you the actual spec, but you'll do fine with where you got them set for now.

 

Still dont have that thing goin yet danny boy? Gonna have to bring it to me and let me tweak, haha. So do you have the valves right yet? Did you go get a compression guage like i suggested?