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Author Topic: Are valves matched to their seat?  (Read 2099 times)

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Offline Scott S

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Are valves matched to their seat?
« on: November 01, 2011, 02:35:32 PM »
 What I mean is, if I disassemble a head for cleaning and porting/polishing, do I need to keep the valves with the cylinder/seat they came out of?

 They will be, at the least, lapped before being reinstalled.
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Offline dave500

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Re: Are valves matched to their seat?
« Reply #1 on: November 01, 2011, 02:44:31 PM »
yes you MUST keep each valve in its original seat.
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Offline Rigid

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Re: Are valves matched to their seat?
« Reply #2 on: November 01, 2011, 02:54:49 PM »
If you are renewing the guides and cutting the seats, No.  If you are only lapping the valves, yes.
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Offline trueblue

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Re: Are valves matched to their seat?
« Reply #3 on: November 02, 2011, 05:17:35 AM »
Quote from: Rigid on November 01, 2011, 02:54:49 PM
If you are renewing the guides and cutting the seats, No.  If you are only lapping the valves, yes.
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Offline Scott S

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Re: Are valves matched to their seat?
« Reply #4 on: November 02, 2011, 05:30:12 AM »
 What about springs and keepers? I'll probably get individual baggies and keep everything together the way it came out, but just curious about the springs.
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Offline tango911

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Re: Are valves matched to their seat?
« Reply #5 on: November 02, 2011, 06:04:53 AM »
Quote from: Scott S on November 02, 2011, 05:30:12 AM
What about springs and keepers? I'll probably get individual baggies and keep everything together the way it came out, but just curious about the springs.

I did just that.  I kept the valves and springs etc... in separate baggies and labeled them 1-4. 
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Offline MoMo

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Re: Are valves matched to their seat?
« Reply #6 on: November 02, 2011, 06:40:01 AM »
Not necessary with the springs but I always use the baggie method to keep everything ordered-same with carb rebuilds...Larry
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Offline MCRider

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Re: Are valves matched to their seat?
« Reply #7 on: November 02, 2011, 06:56:09 AM »
But...if you're really anal... get a spring gauge and check that they are all of similar strength.

Naw... don't worry about it.   :)
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Offline Rigid

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Re: Are valves matched to their seat?
« Reply #8 on: November 02, 2011, 07:56:53 AM »
Valves stretch in length, springs lose their strength, where does it end?
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Offline MCRider

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Re: Are valves matched to their seat?
« Reply #9 on: November 02, 2011, 08:06:53 AM »
Quote from: Rigid on November 02, 2011, 07:56:53 AM
Valves stretch in length, springs lose their strength, where does it end?
Can a valve actually stretch?  I can see where the notch holding the keepers could wear, causing the appearance of stretch by looking at the spring. I can see the seat settling causing the valve to rise closing the lash.

Anyway, live and learn.  :)
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Offline Rigid

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Re: Are valves matched to their seat?
« Reply #10 on: November 02, 2011, 08:27:12 AM »
Quote from: MCRider on November 02, 2011, 08:06:53 AM
Quote from: Rigid on November 02, 2011, 07:56:53 AM
Valves stretch in length, springs lose their strength, where does it end?
Can a valve actually stretch?  I can see where the notch holding the keepers could wear, causing the appearance of stretch by looking at the spring. I can see the seat settling causing the valve to rise closing the lash.

Anyway, live and learn.  :)

Yeah, Lycoming actually sells a contour guage to check their valves for stretch.  It fits between the stem and the top of the valve head.  I have not seen one for any other valves but it makes sense with the recurring tension and temperature variations that the valve would eventually get longer.
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Offline the technological J

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Re: Are valves matched to their seat?
« Reply #11 on: November 02, 2011, 08:52:40 AM »
i had a peice of cardboard with 8 holes(two rows of 4) labeled 1-4 and in and ex and then it was easy to lap them and put them back as well as clean the carbon off em or polish them
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Offline Scott S

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Re: Are valves matched to their seat?
« Reply #12 on: November 17, 2011, 07:40:03 AM »
 Is there a trick or an easy way to disassemble the head at home if I don't have a valve spring compressor tool?
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Offline MCRider

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Re: Are valves matched to their seat?
« Reply #13 on: November 17, 2011, 08:24:29 AM »
Quote from: Scott S on November 17, 2011, 07:40:03 AM
Is there a trick or an easy way to disassemble the head at home if I don't have a valve spring compressor tool?
You can get (borrow) a spring compressor from the local auto parts store, usually for free. The smallest autoi size may still be a bit large for you, but it can done.

Good VSC kits are $40-$60.

http://www.amazon.com/MOTORCYCLE-DIRTBIKE-VALVE-SPRING-COMPRESSOR/dp/B004NV21YA

I'd spend a little more than this myself. But if its a one timer... resell on ebay.
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Offline the technological J

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Re: Are valves matched to their seat?
« Reply #14 on: November 17, 2011, 08:56:02 PM »
if you know a welder you could have him make you something out of a c clamp.... but for dissasembly i have put a large socket on them and smacked the with a hammer... it works but you def need a valve spring compressor for reassembly
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Offline dave500

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Re: Are valves matched to their seat?
« Reply #15 on: November 17, 2011, 10:04:45 PM »
with the socket whack method,stuff the combustion camber full of rag on the pair of valves you are removing,itll stop them from compressing down,watch those collets(keepers).
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Offline Rigid

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Re: Are valves matched to their seat?
« Reply #16 on: November 18, 2011, 02:44:20 AM »
That explains the bent valves I removed ............ ::)  ................. buy the proper tool.
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Offline dave500

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Re: Are valves matched to their seat?
« Reply #17 on: November 18, 2011, 02:49:49 AM »
i dig that k,i mean rigid,,it takes a certain finesse,for one the socket has to clear the stem and seat on the retainer cleanly,and the blows have to have some knowledge behind them,blindly belting #$%* only results in tears,,lays waste to my favourite saying of "WHEN IN TROUBLE OR IN DOUBT,GET A BIGGER HAMMER OUT!"
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