How to tell if a head is ‘any good’?

[gs.davies]

I went to pick up an engine hoist at the weekend so as to move project LFF along and in the vicinity, a ‘Classic Mini cylinder head n’ was advertised for the price of a round of beers. From the pics I could tell that it had had some work done on it and as it came with a free pile of other niknaks I picked it up.

It’s a CAM4810 casting with what appear to be 31x27 inlet and exhaust valves, double springs, chamber debeaked and compared to another CAM4810 I’ve got on the bench, enlarged ports.

There are no other markings on it, and I’ve yet to strip the valves out of it, though the surfaces of them look very clean as it it has been in good running order.

Apart from cc’ing it and matching to my engine spec, are there any ways I can tell if it’s any good?

The seller knew nothing about it other than that it came in a roll cab he bought a while ago. The owner of the roll cab had emigrated to Australia twenty years or so ago and was heavily into minis.

Anywhere I can look for clues as to its usefulness?

Cheers
Gary

[timmy201]

You can check:
Fill the chambers with petrol and check for leaks
Valve seat condition and presence of hardened seats
Valve stem/guide tolerance
Flatness of the head gasket surface
Condition of the rocker post and thermostat hole threads

[gs.davies]

You can check:
Fill the chambers with petrol and check for leaks
Valve seat condition and presence of hardened seats
Valve stem/guide tolerance
Flatness of the head gasket surface
Condition of the rocker post and thermostat hole threads

Thanks Timmy, all good stuff.

It was the performance aspect of the head that I was really thinking of. Short of checking those things you listed bolting it on and running it, I was curious to know if there were things that could be checked to see if the modifications were good or bad.

[abs]

I seem to recall a 27mm exhaust valve is right on the limit of touching a standard 998 bore but I might be wrong.
Other than that it sounds like a potentially great find

[Exminiman]

Presume it doesn't have any marks on it ?

Photo might help, but really its down to who did the mods and how good they are.

Could start by comparing ports and seeing if the porting matches between ports, if they dont match like for like, that does not bode well.

As was modded a while ago, they might of used the yellow book as a reference, so you could try comparing the two.

Might be an ideal to cc it first though, in case is too high for you to use.