Valve Spring Replace or Reuse

Anonymous-0 · Jul 24, 2009

I need to get the head rebuilt for may Case VAC. How do you determine if you need to replace the valve springs? The local machine shop I used to inspect the head for cracks said the springs need to be replaced. None are broken. Just how critical is it to have accurate length and compression force springs for an engine that only turns 1500 rpm? Thanks for the help.

Kruse · Jul 24, 2009

Do you ask him if a shim would fix the valve spring height and pressure problem?

bo · Jul 24, 2009

You got a bit invested, invest a bit more. Springs get tired over time. Of course, you could speck out the height and maybe go with it but you're this deep into it, you might as well......

Anonymous-0 · Jul 24, 2009

Do you have the parts at your place? If so at least compare the free length to specs. I would put new springs in it. Remember they hold the valve on the seat so that heat can be transfered. It is not the RPM of the engine.

Anonymous-0 · Jul 24, 2009

Sounds like they tested them for you.Somebody that went to engineering college wrote a service manual and called for a spec that was not met.Replace.

DickL · Jul 24, 2009

The JI Case specs for the valve springs would be 111 pounds when compressed to 1 17/32.

The little Allis Chalmers springs are only 70 pounds compressed to 1 7/16.

I test every spring I reuse and place them is sets that have the same pounds of test. I have used some sets at 60 pounds at the 1 7/16 at above the rated rpm's with no float problems.

I have not rebuilt a VAC head but would not know with more research why they would require 31 more pounds of pressure than the Allis Chalmers engine of about the same CI other than a larger diameter valve stem.

DickL · Jul 24, 2009

I have cleaned and set 20 or so springs close to one another on a table with no noticeable height difference and and have as much as 20 pounds difference. If you want to bring them here I will test them gratis

Anonymous-0 · Jul 24, 2009

Cam profile?Larger valve head requiring more pressure?

lucas boy · Jul 25, 2009

its critical if they are varying alot in heights, a short spring shimmed has a better chance of breaking or burning a valve.you either trust the machineshop or you dont..lucas

Brian Jasper co. Ia · Jul 25, 2009

All of the springs on my CA Allis and Oliver 60 got replaced. They weren't very expensive. I looked at it like this: They were nearly 60 years old, I wanted to do a first class overhaul, didn't want to ever have to open it up again except for valve lash. The other consideration of heat transfer from the valve to seat is a concern if you ever plan to work the tractor.

Aaron Ford · Jul 25, 2009

Mine was a no-brainer. I could push several down by hand, some with fingers only. Some were actually at spec. They were cheap.

Hope yours are too.

Aaron

buickanddeere · Jul 25, 2009

Replace all. Cheaper than banging a valve into a piston. Or trying to find a mysterious miss.

Valve Spring Replace or Reuse

Anonymous-0

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Kruse

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bo

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DickL

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DickL

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lucas boy

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