45 Valve Spring Length

[Rex]

My valve springs are too long by this much:

Front IN: .086
Front EX: .081
Rear IN: .108
Rear EX: .081

I can't find a +/- tolerance spec for this. Close enough or replace?

[T. Cotten]

Better too long than too short, Rex!

They seem, at least, almost consistent, and it wouldn't be hard to grind the RI to match. But all that really matters is the installed poundage upon the seat, and its easy to shim that to spec.

(Whatever we conjure for a spec, anyway.)

Got a drillpress and a bathroom scale?

SPRGPRSS.jpg

After your seats have been re-cut, you can measure the installed spring heights, and it is possible the long springs are a benefit. The long one may suit the deepest seat.

....Cotten

[Rex]

No drillpress, 2 vertical mills and an arbor press. I have a Baldor grinder with a 2" belt sander attachment I could use for grinding, but no fixture of squaring. Grind by hand and use machinist square close enough?

Seems like you may have a seated poundage in mind...

[T. Cotten]

No drillpress, 2 vertical mills and an arbor press. I have a Baldor grinder with a 2" belt sander attachment I could use for grinding, but no fixture of squaring. Grind by hand and use machinist square close enough?

Seems like you may have a seated poundage in mind...

Let us hope you don't need to grind anything, Rex!

First find your installed heights, and then record their pressures at that height. Then you can shim the springs to be equal.

As far as final pressures, I would be conjuring. It would probably run as low as forty, but I bet racers aim for twice that. Let us hope somebody with specs speaks up...

....Cotten
PS: A trick for measuring installed heights is to assemble using just a brake cylinder spring between the collar and a shim the same thickness as the cover.

That's a sawed-off valve in the chuck in my previous pic. My arbor press worked as well...