Valve spring pressure

[Quickshift409]

How much spring pressure, seat and open are you using. I have a Crane cam with 560 intake and 583 exhaust lift. Any info is welcome, thanks guys.

[CDNpontiac409guy]

Shan, on that cam, pressures close to a factory 64/65 big horse 409 would be good.
I'd say around 135 on the seat, 300-310 on the exhaust at full lift.

Nice cam. I've used that one a few times... including in the 425 horse in my old Pontiac convert.

[walkerheaders]

Ditto on my 409 with Comp Cams double springs. 135-310 worx good street and strip. will rev to 6500 easy and safe.

[fatride]

My thougts almost to the pound. Is that a solid grind? I had better watch out next season huh? :p

[CDNpontiac409guy]

Nice cam, Fat.
Before Comp and others got on board with modern profiles, Crane was WAY ahead of everybody else. That cam is a solid, flat tappet. 238 / 248 @ .050", ground on a 110 C/L. Will have a nice, rough idle at around 800-900 RPM, comes on strong at around 2800, and yes, with good headers, shift at 63-6500.

Basically, it's like a high lift version of a stock 63/64 400/425 horse cam, with quicker ramps, and just a touch more duration... but less than the late 64 / Z11 cam ( while still having more lift than that cam ).
This cam WILL work with 583 heads, using the correct springs for the late 64/65 engine. The taller installed spring height, has no problem with the extra lift.
I would recommend Comp Cams "986" or "987" dual springs ( depending on installed height ).

Ironically, I have found that Crane's recommended 99893 dual spring, has WAY too much pressure, when installed with stock length valves. I haven't checked when put on 583 heads though. MAY be OK:dunno


whoa
got kinda carried away there:rolleyes:

[Quickshift409]

Aubrey, thanks for low down on the Crane cam, I do run 583 heads but don't know what springs they have.

[GOSFAST]

That is the identical cam, spec-wise, that we've done some extensive track testing with most recently on a BBC with 2.190" intakes and some 1.7 rockers.

This is basically the same setup as the "W" unit.

You will need 140# closed at whatever installed height you are starting with and you will need 350# open, at your mentioned lift, to get "through-the-traps" at about 6500+.

The overall valve weights become a "major" factor in the final performance. I use nothing but SB (.343") stems in this program. With the "large" valve heads I use a 2.190 intake and a 1.770" exhaust. The valve lengths average 5.200" with the "keepers" down .250"! This add'l length, "installed-height", helps reach the higher lifts at the valve without worrying about retainer/seal clearances or
"stacking" the springs. Been doing this procedure on these "W" units for years now.

If you are using "small valves" the rules may vary some slightly! By all means get rid of the .375" stems no matter what valve size you end up choosing. This step alone allows some 4 CFM add'l air "in-the-hole" at upper RPM's.

The 300# open number will cause issues with respect to reaching your RPM goals!



Thanks, Gary in N.Y.

P.S. The springs you mention, Crane's 99893 and Comp's 986's/987's are all SB springs. I know Crane call's to use this number on certain BB's, but it's basically a SB spring!

[Skip FIx]

Flat tappet? solid, hydraulic? hydraulic roller? 1.8 rockers?

A hydraulic flat tappet generally can get away with a little less seat 120-130. But gofast is about right on for solid or even a HR. And as he said our valve train is heavy so it needs a little more pressure to keep things where they are supposed to be.

More aggressive lobes need a little more seat duration especially if you get crazy like Aubrey and those stockers "cheater" cams.

[Chalupa58']

Since we're on the topic of cams and springs. I heard somewhere that the "W" engines don't respond well to cam changes due to the fact that the combustion chambers are cast into the block. Is this true?
I was thinking of running the Crane Cams #H-218/300-2S-12 cam in my 348, but haven't purchased due to what I had heard. I figured if it was true I should just stick with a stock cam. I just want to give my 58' a little more hop in her gitty up. Thanks in advance.:cheers