lapping in valves

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Apr 26, 2003 | 09:31 PM

dustinleavitt2000

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From: ca

lapping in valves

I did a 3 angle valve grind on my valve seats and got seats pressed into the exhaust. My question is do I need to lap in my valves and how would I go about doing so.

Apr 26, 2003 | 10:07 PM

BentWheel

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Joined: Mar 2003

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From: around Salem OR

lapping in valves

No you don't need to lap the valves however if you didn't get your valves ground have them ground at an angle that is one degree smaller than the seat angle i.e. a 45 degree seat and a 44 degree valve. FYI valve grinds are desireable even with brand new valves

Apr 26, 2003 | 10:34 PM

dustinleavitt2000

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From: ca

lapping in valves

I bought new valves and i am really unsure of what to do now. could someone give me a run down of how install the new valves?

Apr 27, 2003 | 02:33 PM

dustinleavitt2000

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From: ca

lapping in valves

I did a kind of hasty job on the 3 angle grind would lapping them help?

Apr 27, 2003 | 03:00 PM

shazam

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Joined: Feb 2001

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From: Porterfield

lapping in valves

OK if your really not sure I'd take it to a Machine shop and let them do it ... You have to make sure the angles are right and the installed spring height is right with the seat pressure....

Apr 27, 2003 | 03:16 PM

gregdatech

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Joined: Mar 2002

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From: Sapulpa

lapping in valves

Lapping will do a finishing job on seating the valves. If the angles are way off etc, it wont help. It wouldnt be a bad idea to lap them just to make sure they will seal before you put it all together. Sometimes machine shops arent perfect, and its so simple and quick why not?

Apr 27, 2003 | 05:40 PM

dustinleavitt2000

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Senior User

Joined: Nov 2002

Posts: 316

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From: ca

lapping in valves

I just lapped in one valve, it appears that i made the single groove way too small because after lapping its bigger.

I installed it and filled the port with wd 40 and it doesnt appear to leak from the valve.

Is this a viable way of telling if I have a good seal or not?

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Apr 27, 2003 | 06:27 PM

BentWheel

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Joined: Mar 2003

Posts: 44

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From: around Salem OR

lapping in valves

Sure lapping can help on a rare occasion but it's also a better way to screwing up a good valve job. To check the valves for sealing get some perusian blue, it comes in a tube and you coat the face of the valve with it and then smack it against the seat, if the seals are good their should be a line around the valve a few thousands in from the edge.
I agree with shazam thought, if your not real sure on how to do this stuff let someone else do it or learn how to do it before trying.