Can I shop cut new keeper notches on valve stems? 6

[Torquey]

Dear Gentlemen,
Every now again I get a hare-brained idea that I need to run by the Eng-Tips wizards. There is no other website that compares to this one when a fellow needs a correct answer. Here is my latest hare-brained notion...

I have a new set of stainless steel forged valves that go in a 32-valve Ford 4.6L DOHC. I want to use stock springs but these valved have the triple groove keeper slots cut a few mm higher to accommodate high-lift (longer) springs. My questions:

#1) When manufactured, are valve keeper slots forged into the valve stem or are they cut on a lathe?

#2) Can I expect a machine shop to be able to effectively cut new sets of keeper slots at the stock locations without any problems i.e., assuming a shop can do this are there any caveats?

 

[patprimmer]

Can you use spacers under the spring seats.

Regards
Pat
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[ivymike]

I think that they're usually cut, and that you should be okay (might depend on whether they harden the tip of the valve and if so how far down the stem the hardening goes), but Pat's suggestion accomplishes what you're after and has less risk.

 

[blacksmith37]

Not my business, but I can think of a lot of possible problems :1- Stem could be case hardened-then you would cut through to the softer core.2- Should it be cut or ground?, radius and finish at the bottom are critcal (I have seen turbine blades fail due to these imperfection in the "fir tree").3- If the exhaust valves are very high performance ,they may have sodium cores/hollow.4- The stems may be chrom plated.etc.

 

[Torquey]

I've never seen a shim that large. Can you shim 2/10"? I know there are stackable shims but, good gravey, you're talking a huge numbers of stackable shims to get to 2/10".

 

[MikeHalloran]

Any machine shop can make shims 0.200" thick from steel rounds or hollow bar, probably for less money than form grinding new keeper notches.



Mike Halloran
Pembroke Pines, FL, USA

 

[evelrod]

Good grief. If I did not cut my own valves to size I would never be able to keep most of these race engines running. I commonly cut down Datsun L-20 intakes and L-18 exhaust valves to fit the Lotus twincam engine. I have also used Jag valves, but they are no better than the Datsun valves but cost a lot more. Just be sure that the groove you cut matches the keeper you intend to use. Obviously you should seek out craftsmen that can do a PROPER job of it, that goes without saying.

As to 'shims'..."lash pads" can be made from bar stock for simple pads in just about any thickness you wish, however, they can be purchased from several mfgrs in thicknesses of a quarter inch. I have a bunch of 0.200" Jag shims that I use as blanks to grind down to whatever thickness I need. Mostly I use the Alfa type cup pads that I had a master machinist and racer make up for me many years ago.

Rod

 

[Torquey]

Does anyone have a good online source for thick shims? These springs have a rather small diameter (~1") so I would think a source would need to have a large selection to stock such a small diameter shim.

 

[patprimmer]

How about a piece of steel plate of appropriate thickness and a hole saw same OD as spring, then bore the centre hole to clear valve guide.

Regards
Pat
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[evelrod]

Sorry, I'm used to doing DOHC engines. If your looking for valve spring base shims to set the installed length...
These internet sites are where I have bought base shims in the past.

http://www.phoenixspecialty.com/?gclid=CKPJwZfvzqgCFQkFbAod8BgihA

http://www.pronto.com/user/search.d...alve spring shims&creativeid=3266065420&site=

http://www.summitracing.com/search/...ne/COMP-Cams-Valve-Spring-Shims/?autoview=SKU

I also had custom base shims for a Cosworth engine made for me by Isky years ago when I was friends with their design engineer.

Rod

 

[Torquey]

Mr Pat, Thank you for the idea. That's is so simple, it's ingenious! I was thinking the home-made solution would be to buy some round stock but a flat sheet and a hole saw would be the way to go. Is aluminum sheet too soft a material for valve shims or would you use steel?

 

[patprimmer]

On aluminium heads they normally use a thin steel pad under the spring. If your engine has an aluminium head, the OEM pad could be used top of an aluminium spacer. I would use a hard grade of aluminium

Regards
Pat
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