What is a "valve job"?


5 replies to this topic
  • minioutlaw

Posted August 08, 2004 - 05:58 PM

#1

When people speak of a valve job, what exactly does that entail? New valves? Can valves be reused/reconditioned? Do you always grind/lap the valve seats? What about valve guides; I've seen them for sale in over bore sizes. Do you need to buy an overbore size if you are replacing original guides? Are there other parts that need to be replaced when you are rebuilding a head? Thanks,

  • flyinW

Posted August 08, 2004 - 07:09 PM

#2

Forrest...

New valves?

Yes...Maybe... if the damage is beyond repair... personally I would change them if/when I'm in there if they are not in primo condition.

Can valves be reused/reconditioned?

Yes... see above

Do you always grind/lap the valve seats?

Yes... most often the seats are ground to match the valves (which may be ground as well)

What about valve guides; I've seen them for sale in over bore sizes. Do you need to buy an overbore size if you are replacing original guides?

No... not neccessarily... oversized are usually for damaged heads. The area where the valve guide is pressed into is worn or elongated and thereby need reaming and o/sized guides. If not, the std's are OK.

Are there other parts that need to be replaced when you are rebuilding a head?

You Betcha! Gaskets, seals, springs, hp cam... and who knows what else...The best thing you can do is make absolute sure of the machinist that you're taking the work to... that he has a great reputation and comes to you by word of mouth. As you can prolly guess there are good ones, not-so-good ones and GREAT ones!!
Good Luck :thumbsup:

  • frankstr

Posted August 09, 2004 - 02:52 AM

#3

Valve Job....Tearing down cylinder head,cleaning head or heads and parts,Inspecting parts,Grinding good valves and seats,setting installed height,cleaning parts again and reassembly..
Any parts that need replaced valves,guides,surfaceing head,etc.are usally above the (valve job price) :thumbsup: :devil:

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  • minioutlaw

Posted August 09, 2004 - 06:08 AM

#4

Thanks for the info, guys.

  • cpifer

Posted October 31, 2006 - 06:20 PM

#5

when looking for a machine shop to do your work, look for a shop that is set-up to work on small diameter valve heads, such as the ones found in sport compact cars or 4-stroke dirt bikes. The concentricity between the valve stem centerline and guide bore centerline need to be held at much closer tolerances than say a small block chevy. This is due to the small diameter of the valve stem being much more sensitve to deflection etc...

  • creeky

Posted October 31, 2006 - 07:14 PM

#6

Check this out www.dansmc.com/valve.htm





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