New/old valve

[mikey]

I have to replace an inlet valve while i appreciate if i fit a new valve will have to have the valve seat for that valve re cut. i do have a spare head if i took a valve from that would it be sufficent to just lap it in.

[steve f]

yes

[mikey]

Cheers steve thats what i like a no nonsense answer

[MaineKZ]

Would it help if I said...'depends'?

[Jeff Saunders]

depends...

generally yes, you can get away with this, but be aware valve/valve seats wear as a pair - to get the replacement valve to seat, you may end up lapping in too much and broadening the seat beyond what's normally acceptable.

[mikey]

Thanks guys jeff how would i know if i have lapped in the valve to much
and broadend the seat to much or would it be easier just to have the seat recut for the new valve, and if thats the case would it be worth having them all done and while were on the subject of valves what do you look for to tell if guides or worn cheers guys sorry to go on but youre dealing with someone who maybe worries to much.

[Jeff Saunders]

The workshop manuals give an illustration of the width of the valve seat - it's only approx 1.5mm or so..

Valve guide wear - the shop manual also mentions this - basically you check the amount of play with the valve extended out from the seat. If you replace guides, then you will need to recut the seats - the problem with some guides is the bore isn't perfectly centered.

[ROZZER]

Mikey, be very careful not to remove too much metal when getting seats recut, danger is you can go below minimum shim thickness of 2 mm. You can top off the valves to recover up to 0.3 mm (if it hasn't already been done). Check shims/valve lengths before starting to determine how close to minimum you are.

[DogsbolloxofZ1B]

As said previously. the manual is very detailed wrt valve/valve seat data, but also make sure you check p171 (I think) this gives the table of how much the valve shaft should extend into the head and whether the stem would need regrinding.