valves etc

[ampwhu]

i am almost finished on building my spare engine. my attention is turning to the head.

i have decided to fit new exhaust valves. i have purchased them for a few pence (result, they are new as well). i have the compresser, stick and paste.

the question is, how do i know if i have ground them in right? is there any signs that i've done it right before i fit it to the car? it seems too easy to get it wrong, but with everything in life....... there's a snag.

this may seem easy to most, but as i have never done this before, i'd like some advice please.

thanks

[Alec]

Hello Ampwhu,

you can see where the seat has been lapped in as it leaves a light grey 'witness' where it's been lapped. A lot depends on the condition of the seats, if they are badly out of shape, i.e. not a nice clean flat 45 degree face they will need machining\cutting which an engine re-builder will need to do. Poor seats take a long time to just lap in and will not be as good as having them dressed true.

Alec

[bmcecosse]

One test is - dark room - shine a small bright light up the port - and look to see if any light is showing around the rim of the valve. But as above - just grind away until there is a nice even grey surface on seat and valve.

[beero]

I am doing the same myself. Couldn't get on with the stick so laid the head on it's side and put the stem of the valve in a cordless drill on slow speed, alternating direction on the drill every time I add a bit of paste. One bonus is the paste doesn't run down the stem into the guides. To test, clean everything up and refit valves and springs and pour paraffin into the ports. None should leak past the valve into the combustion chamber.

[billlobban]

Should the seats need recutting its not necessary to go to a machine shop - beg, borrow or steal an appropriate set of hand operated cutting tools (quite often on fleabay). Not rocket science