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How do you know if a head is unleaded
200mph - 5/1/04 at 07:56 PM

I believe the head from my x-flow engine is an unleaded one, but how can I check this?

I want to be sure before I sell it, so is there any visual difference between the valve seats of a leaded and an unleaded head? Or would there be a stamp somewhere on the head?

Cheers,
Mark

sweston - 5/1/04 at 08:59 PM

I have just had my XFlow head converted to un-leaded.

Look at the exhuast valve seats and you should clearly see the "hardened" insert that has been put in.

Hope that helps.

200mph - 5/1/04 at 09:12 PM

Is the valve seat just the place the valve comes ot rest, or is it an actual 'thing', i.e. could you remove and replace a valve seat?

Think I'm making this more difficult than it needs to be, but don't know how else to phrase it.

So I am looking for a distinctive instert.

Cool

Many thanks,
Mark

Stu16v - 5/1/04 at 11:19 PM

quote:

Is the valve seat just the place the valve comes ot rest, or is it an actual 'thing', i.e. could you remove and replace a valve seat?


A bit of both really. It is what the valve sits on in the head, and hardened 'inserts' are fitted in place of the old seats (which would be part of the original head casting), by machining the old ones out.

Trouble is, just because the head *may* have the valve seats replaced, it doesnt unfortunately follow that they are hardened ones. Potentially, your cylinder head could be getting on for 40 years old and could of had the seats replaced as a reconditioning process as opposed to an unleaded conversion.

HTH Stu.

200mph - 6/1/04 at 04:56 PM

when i bought the car, the guy said the engine had an unleaded conversion, but he never said *he* had it converted. I also assumed that I would be able to tell visually, i.e i could tell the valve seats were different, but by lookinjg at the head is difficult to tell.

The seats look a different colour, but because they are at a diferrent angle this might be the cause? also, there doesnt appear to be anything thats been insterted as such....which makes me suspicious.

is there anyway i could test the petrol from the tank? could send it to my petroleum engineer mate, but he's in london just now, and somehow I dont think thats safe

might just sell it as a standard head then, and someone may pick up a bargain

cheers,
mark

Stu16v - 6/1/04 at 07:09 PM

Having the petrol tested will only confirm that the previous owner was using unleaded, and unfortunately not that the head had been converted......

chrisg - 6/1/04 at 07:35 PM

The insert should be visible as a ring 2 to 3 mm outside the valve seat, clean it up and have a look. The whole valve seat is cut out and a ring of harder material is inserted and the valve seat is cut into this - no ring, no unleaded.

Cheers

Chris