7 replies to this topic

[doormatt]

I was having a clear out and have decided to sell this, anyone know what its worth as I'm clueless. All I know about it is that is a 12g295 head 

 

 

 

 

 

[6joshh6]

You really want to clean it up, inspect it for cracks, get an idea of the valve seat condition and valve size. I'd also check if it has been skimmed and by how much. Has it been ported? all these factors will influence it's value. As it is, I'd probably estimate around £100-£150 as it stands, more if it has some nice porting or is entirely original, as original heads are hard to come by.

[doormatt]

You really want to clean it up, inspect it for cracks, get an idea of the valve seat condition and valve size. I'd also check if it has been skimmed and by how much. Has it been ported? all these factors will influence it's value. As it is, I'd probably estimate around £100-£150 as it stands, more if it has some nice porting or is entirely original, as original heads are hard to come by.

How would I go about finding this out? Will it be a case of finding an engine builder and getting them to look over it?

[6joshh6]

 

How would I go about finding this out? Will it be a case of finding an engine builder and getting them to look over it?

 

You could send it to an engine builder but it would probably cost you as much as you'd gain from selling the head. You can easily check a head at home with basic equipment. Firstly, you'll want to get either petrol or paraffin and a suitably small wire brush. Clean the carbon from the chambers and valve ports. Then have a good look at the valve seats, basically, you're looking for any pitting, like in the picture below. Slight discolouration is fine, as a quick lapping in will get that out, but if there is anything which is obviously pitted, that will need further attention. Next take a bright light, a desk lamp or similar is adequate, and have a look at the area between the two valves in each combustion chamber. If there are any fine lines apparent between the two, there is a crack, like in this photo.

 

Measuring valve sizes is nice and easy, just get a ruler or similar and measure it to the nearest mm. Checking whether the head has been skimmed can be done in two ways, either measure the combustion chamber volumes, or by measuring the head thickness. The head should be 2.75" thick or 69.85 mm, this needs to be fairly accurate so ideally use a vernier calliper or at a push, you can use a ruler to give a rough idea of whether it is roughly standard or heavily skimmed. The combustion chamber method of measuring is nicely explained here http://www.theminifo...atio/?p=2442330

 

Looking at the photos, it doesn't look to have had any modification to the combustion chambers, and the ports look standard (the recess for the manifold locating rings are present so it hasn't had the ports opened out. So really, all you have to do is look at the valve bosses, indicated with the arrows in the photo below. If they have been ground down or are no longer 

there, the head has been ported slightly at some point.

here

 

Hope this helps,

 

Josh

[Sheikh Pip]

Looking at the valves I'd say that's been tuned big time!

[blacktulip]

Looking at the valves I'd say that's been tuned big time!

please explain? it looks standard to me.

[doormatt]

How would I go about finding this out? Will it be a case of finding an engine builder and getting them to look over it?

 
You could send it to an engine builder but it would probably cost you as much as you'd gain from selling the head. You can easily check a head at home with basic equipment. Firstly, you'll want to get either petrol or paraffin and a suitably small wire brush. Clean the carbon from the chambers and valve ports. Then have a good look at the valve seats, basically, you're looking for any pitting, like in the picture below. Slight discolouration is fine, as a quick lapping in will get that out, but if there is anything which is obviously pitted, that will need further attention. Next take a bright light, a desk lamp or similar is adequate, and have a look at the area between the two valves in each combustion chamber. If there are any fine lines apparent between the two, there is a crack, like in this photo.
 
Measuring valve sizes is nice and easy, just get a ruler or similar and measure it to the nearest mm. Checking whether the head has been skimmed can be done in two ways, either measure the combustion chamber volumes, or by measuring the head thickness. The head should be 2.75" thick or 69.85 mm, this needs to be fairly accurate so ideally use a vernier calliper or at a push, you can use a ruler to give a rough idea of whether it is roughly standard or heavily skimmed. The combustion chamber method of measuring is nicely explained here http://www.theminifo...atio/?p=2442330
 
Looking at the photos, it doesn't look to have had any modification to the combustion chambers, and the ports look standard (the recess for the manifold locating rings are present so it hasn't had the ports opened out. So really, all you have to do is look at the valve bosses, indicated with the arrows in the photo below. If they have been ground down or are no longer 
there, the head has been ported slightly at some point.
here
 
Hope this helps,
 
Josh

Wow really helpful thanks!

[carbon]

 

You really want to clean it up, inspect it for cracks, get an idea of the valve seat condition and valve size. I'd also check if it has been skimmed and by how much. Has it been ported? all these factors will influence it's value. As it is, I'd probably estimate around £100-£150 as it stands, more if it has some nice porting or is entirely original, as original heads are hard to come by.

How would I go about finding this out? Will it be a case of finding an engine builder and getting them to look over it?

 

 

Couple of quick checks you can make. First measure the diameter of the inlet and exhaust valves in mm, as these are not the original valves.

 

Second measure the overall depth of the head from top to bottom. This would have been 2.75 inches when it left the factory, if it is less than this it has been skimmed at some point.