Checking Valves - Paraffin?

[jcas]

Hi Guys,

I've just had my cylinder head recon'd, including the valve seats. I lapped the valves in until I had a dull grey band around on both head and valve, then refitted the springs (after cleaning up). I read to check the seal you can turn the head upside down and fill the tops of the combustion chamber with paraffin to see if it drains down through the ports. It has on a few but only a very slight dribble. Is this a good way of checking or is paraffin too thin? Is a small dribble acceptable or should I take the valves out and lap them some more?

Thanks,
James

[denisb]

[redacted]

[Pigeon]

I do it the other way up - fill the ports with diesel and see if it appears in the combustion chamber. It's easier to spot small leaks that way and for a diesel I go for a perfect result. For a petrol it's not so important; a good visual check of the lapped faces is often enough.

[Trooper2]

Rubbing alcohol works as well.