Valve grinding

digi · Nov 24, 2014

I cleaned the build up of carbon off al 16 valves then used fine grinding paste to lap each valve by hand until i got a grey ring round each valve.

Is it possible to get a 100% percent air tight seal, when i re fitted the valves and tested with water in the crown and blew air in the ports i have small leaks, is there an acceptable amount of leakage or do i need re do them.

Gaj1612 · Nov 25, 2014

f*ck doing it by hand wack a drill on the vavles haha

jamesmartin · Nov 25, 2014

Gaj1612 said:
f*ck doing it by hand wack a drill on the vavles haha

you never did a proper apprenticeship then

jamesmartin · Nov 25, 2014

digi said:
I cleaned the build up of carbon off al 16 valves then used fine grinding paste to lap each valve by hand until i got a grey ring round each valve.

Is it possible to get a 100% percent air tight seal, when i re fitted the valves and tested with water in the crown and blew air in the ports i have small leaks, is there an acceptable amount of leakage or do i need re do them.

it is possible , but in reality they dont have to be perfect , once youve lapped valve clean off all paste and lap dry for 30 seconds you should have an unbroken ring

Gaj1612 · Nov 25, 2014

Yep and then learnt that a lot of time can't be saved lapping valves with a drill till they're almost done and finishing them off by hand.

Gaj1612 · Nov 25, 2014

Can be saved** stupid phone

jamesmartin · Nov 25, 2014

Gaj1612 said:
Yep and then learnt that a lot of time can't be saved lapping valves with a drill till they're almost done and finishing them off by hand.

did you not have access to a seat cutter

Gaj1612 · Nov 25, 2014

I did not, unfortunately.

Iainb72 · Nov 25, 2014

Ive never tested a head like that before, what pressure air are you pumping in?

I would have thought after lapping that you wouldn't get leakage (though to be fair the last set of heads I did were for a V8 running massive spring pressures due to the cam I was using)

htr · Nov 25, 2014

digi said:
I cleaned the build up of carbon off al 16 valves then used fine grinding paste to lap each valve by hand until i got a grey ring round each valve.

Is it possible to get a 100% percent air tight seal, when i re fitted the valves and tested with water in the crown and blew air in the ports i have small leaks, is there an acceptable amount of leakage or do i need re do them.

A common test for leakage is when all reassembled to spray some brake cleaner into the runner and see if any leaks out.

Have a close look at the valve faces after your grinding. You may notice a slight mottled patted - the remains of surface pitting. However, even with that it should provide a good seal. Don't be tempted to use an electric drill. It can cause damage that hand grinding could never do and in the blink of an eye too.

Tried and true methods are best.

Valve grinding

digi

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Gaj1612

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jamesmartin

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jamesmartin

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Gaj1612

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Gaj1612

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jamesmartin

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Gaj1612

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Iainb72

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htr

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