Valve Spring Mayhem

R

riley_smitty

New member
Hey guys,

This one part has been a thorn in my side for a while. Tons of mixed messages. the book says shim stock spring by ,i think, 0.03" and you can get 6000 rpm. others in the forum say the 302 exhaust springs are no better than stock springs. just need some clarification.
I will be running a 264/274 clay smith cam. the clay smith cam shaft calls for 120-130 lbs of closed seat pressure. my theory is that i take the 302 exhaust spring that is spec'd at 100 lbs closed pressure and shim the spring to reach the 120-130 lbs req'd for the cam. I wanna stay away from dual springs as it adds a lot of money to my budget and it doesnt allow me to reuse my original retainers and locks and requires more machining to the head. Let me know if you guys think my theory is correct/ would work. i just need the engine to rev to 5000-5200.

Thanks guys
 
sorry, no, no help here,
just glad U got the :
"...requires more machining to the head..."
RE: the dual springs
as it's a new piece of info 4 me and I've been following the alu head a lill for a good while.
(May B U just pay better attention than I). :unsure:: :idea:
 
If your installed height is around 1.650" use the Crane 96803 single spring.

OD 1.437"
ID 1.035"
Seat pressure 123 lbs @ 1.65"
Spring rate 330 lbs/in
Coil Bind 1.037"

Same springs "lavron" is using
 
riley_smitty":38rwwgdv said:
pmuller9 my install height is 1.59 inches. Have you used these springs from crane in your own build?
Click to expand...
Not me. It is "lavron" that has them in his engine but his installed height was near 1.65"
 
I just went through every catalog I have which covers almost every brand of aftermarket springs.
I've done this before but wanted to be sure I didn't miss anything previously.

I couldn't find a "single coil" spring that came close to having a seat pressure in the 120 to 130 lb range at 1.600" and a spring rate between 300 and 350 lbs/in or not go into coil bind at .470" lift with a 1.600" installed height that would also fit your stock retainer.
This has been a problem for a while with both the iron head and the aluminum head where the valves are too short to accommodate the springs needed for high rpm applications.

The aluminum head can be ported to make 300 hp on the 200 six but you need 7500 rpm to it and there aren't any valves spring with the needed pressure and spring rate that is that short.
There have been two members that purchased much longer custom valves from Manley for the aluminum head.

I also looked for 5/16" 7 degree keepers with an + .050" offset with out any luck.
 
thanks for the info! i think what my plan will be is to shim the 302 spring to get as close to 120 lbs as i can. im sure 110 lbs or even 100 will be "OK". but the last thing i want is to rev the car out and have it float at 4500 rpm. i am also talking to lavron so i will see what he has to say.
Thanks
 
thanks for the help guys. so long story short 110 pounds of seat pressure and 245 open will be perfect for the rpm rang im looking for? my car is also an automatic so it might not even hit 5 grand before it shifts. stock trans would shift at 4 grand at WOT so a shift kit is going in.

thanks!
 
Are you also checking that the valve springs after they are shimed for the 120 psi seat presure won't have coil bind at their full open (compressed) spring height? :nod:
 
realized through calculations that i will coil bind the valve springs with the lift i will run on my cam....back to the drawing board. the valve spring drama continues. wishing there was a straight forward/clear cut solution hahaha
 
there may B, let's hol on amin...
:idea:
 
If its an iron head machine the spring seat.015"-.020". Never do this on the aluminium head. Then you can use a spring for a higher installed height.
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