valve float

-
6

67yelodart

Well-Known Member
Joined
Aug 23, 2009
Messages
55
Reaction score
14
Location
bountiful,utah
Hello racers,
I need some opinions,,,I believe i am getting valve float at about 5800 rpm.
I have edelbrock performer rpm heads,,comp cam xe-268 h cam,,1.6-1 crane rockers.
If i changed back to 1.5-1 stock rockers would that get rid of the valve float?
should i add shims to the springs or get new springs?
if i change back to stock rockers am i going to notice performance loss because of the lower valve lift?
any and all advice is appreciated.
Clark
 
You left out 2 important details. What size are the valves and which springs are you currently running? The manufacturer of the lifters might be handy to know also. Gonna take a stab and say your lifters are pumping up due to insufficient preload. It's not easy to get the preload right with adjustable rocker arms. That and Comp lifters are crap. I say that because the only problem I have ever had with stock hydraulic lifters and stamped rocker arms is that they tend to put a pushrod through the rocker around 7500 RPM.
 
ok i'll bite,why does it matter what size the valves are?
they are 2.02 and 1.60,,,,stock springs for the eddy heads
 
What motor do you have? What the spec on the cam? What dist/ign box are you using?

On my 340 in my 67 had RPM Performer heads with a Crower solid that was 248/252 and .525/.528 with all MSD stuff and it would sing all the way to 7200-7400 until is just wouldn't pull anymore. I think the springs are good, I'd double check the dist/ign make sure that up to the task.
 
67yelodart said:
ok i'll bite,why does it matter what size the valves are?
they are 2.02 and 1.60,,,,stock springs for the eddy heads
Click to expand...

The larger the valve is, the more it weighs. The heavier the valve gets, the stiffer the spring you need to control it.
 
grumpuscreature said:
Gonna take a stab and say your lifters are pumping up due to insufficient preload. It's not easy to get the preload right with adjustable rocker arms.
Click to expand...

This is on a Chevy so don't bite my head off. Less lifter preload resulted in more rpm before floating and also it was easier to set the preload with adjustable rockers. I never tighten them down like the book says. ???
 
? why do you think your getting a valve float
? what is really happening when you DRIVE it past 6800 rpm
? could your carb be to small for your app
 
Need more info... Give details of the engine. Generally the edelbrock springs are weak when lifts go up but they should be fine with that cam. 1.6s are harder on a spring too. How many miles on it?
 
I set those eddy springs up tighter than they come OOTB. I think I set them to 1.750 and their good for up to .570 lift that way if I remember correctly.
They work much better that way.
 
Thanks for the replies,,,,,but since my cam only makes power to 5800,and that is right where im running out of power,i will just shift sooner.
 
Patient - "Dr., It hurts when I do this... What can I do?"
Doctor - "Then don't do that..."

If you have a problem causing that, it is also costing power at lower rpms so at some point you might want to look into it.
 
You must log in or register to reply here.
-

Back
Top