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Fistful of Boomstick
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Discussion Starter #1 (Edited)
i got my heads all apart cleaning, replacing the seals and checking play. the heads have verry little wear and all is good for specs but i was wondering about valve lapping. i used to do this with the 2 cycle(ment to say lawn mower and such) motors i used to rebuild for people and dont know wether you do this for automobile heads or will it fawk shit up.
just wondering if i should bother but i do have the heads apart and would only take a few min.
 

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Fistful of Boomstick
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Discussion Starter #2
anyone?
 

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Yes, you can lap the valves if you want to check and refresh the contact area.

However, I'd sure like to know how you lapped the valves on a 2 cycle engine...

Cory
 

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Fistful of Boomstick
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Discussion Starter #5
heheheh ummm typo sorry bout that :flipoff2:
 

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As Cory said above you can lap the valves to refresh them, but you will be much better off taking them to a machine shop and having the seats recut. Lapping will increase the the area the valve is contacting the seat and decrease airflow, and sink the valve into the head lessing compression a tad and if over done the springs under extreme case can pull the valve into the head.

Have them done by a decent shop, it'll be much better. Also they will reface the valves and check the guides for excessive wear and repair as necessary. Plus I don't think lapping will do well on hardened exhaust seats.
 

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Fistful of Boomstick
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Discussion Starter #8
c5sidewayz said:
is this newbie tech? hahahahahaha
thank you for padding my post you worthless fawk, thank you for contributing any helpfull info on my ...........wait ummm oh thats right you apear to be banned :flipoff2:


nevermind:D

thanks for your help guys i am not going to touch them as they look fine after getting all the carbon out of everything and i dont feel like assing anything up:beer:
 

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If you have the time, lap 'em. You'll find out pretty quick if the valve face is pitted and needs refacing or if 'ya got lucky and don't need expensive machine work.
 

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Get some lapping compound and the tool to lap them with.
(a stick with suction cups on both ends)

Pull the suction cup off one end and chuck up in cordless drill.
You don't want a high speed drill.

You can see the valve seat smoothing as you do this.
I highly recommend this if you don't need/want a valve grind.

This seats the valve by smoothing out rough spots on the seat.
I wouldn't pull a head apart without lapping the valves.

I usually spend some time with a dremel in the intake and exhaust ports too. Spend more time smoothing the exhaust.
You don't want a real smooth intake side, just grind down any obvious humps, and match the intake manifold ports.
 

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Valve lapping should be done even after machining. It will make them seall really well. Don't use an electric drill. Lapping should be done using a progresive motion ( forward 3/4 turn then back 1/4 turn). In the old days everyone laped valves often and a common tool is the little tool with a hand crank and a suction cup that makes a progresive motion when you crank the handle. You can buy original ones from the '30s on ebay for cheap or at swap meets. I got an air powered one recently but it cost me a fair amount but it is much faster. I have used it on my diesel heads with hardened seats. You aren't removing much, just making a tight seal. It woun't fix any damage seats or valves. I use medeum then fine Clover grinding compound. Make sure to clean it up really well when done. Use diesel fuel in the ports and then look for leakedge on the other side to see how well they are sealing before and after.
 
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