Valve Guide Lenth for High Lift Cams

[jefflock]

It's my understanding that on X & J heads the guides need to be cut down for camshaft with lift above 480". Is there a specific amount to remove? My Comp cam has .507 & .510 lift. Thanks

 

[70aarcuda]

hydraulic cam or solid cam?

adjustable rockers or non adjustable rockers?

the actual lift at the valve is usually less then the advertised...

due to lash on solids...or rocker arms ratio not being true...

 

[daredevil]

with the retainer on the valve measure clearance from seal to retainer and subtract actual lobe lift multiplied by 1.5 or 1.6 depending on rockers to find out clearance. every head is different depending on installed spring heighth

 

[moper]

In terms of retainer to guide clearance at max lift. Generally when talking stpock engines, you'll hit the valve on a piston before the retainer hits, and that doesnt happen until you get past about .530 lift at the valve. Now, the issue I do know is a problem is with a true double valve spring, the valve seals dont fit, and the spring seat has a step so the inner spring will bind. So you are doing valve guide work, but it's to install positive valve seals that clear the inner spring, and then flattening the step in the spring seat so the spring can work right. Now, on 360s, the exh valves usually have rotators for spring retainers, and those WILL hit the guide top at lower lifts. But once those 8 are replaced with std retainers, there is the same clearance as the others.

 

[jefflock]

Again I didn't provide enough details. Maybe I'll learn one of these days. Comp cams hydraulic XE284H. Using stock adjustable rockers off of a 273 for now untill I figure what length of pushrods to use with my comp rollers.
Moper, Thanks for the info regarding the dual springs. That is what I'll be using.