Valves to piston gap

[Mark Halligan]

Actually Doug, ours look quite similar dont they, Steve yours looks like it was cast just yesterday .

Mark.

[SteveH]

Doug,

My head does have the line just like yours. It's on the pic, slightly further out than yours. I've been working on it during a few afternoons. I don't really have the right tools, so it's just a clean up of the ports and a polish on the exhaust side. Should be finished by the weekend

[Mark Halligan]

how can you be pissed off Mark when your head looks like that - Just put it on your mantlepiece

LOL, I feel a lot better after seeing how similar ours are now, I think I was pissed off cos I will now need to check/balance the combustion chambers now, when all I really want to do is bolt the f$cker on!

Cheers,

Mark.

[Doug_RS2]

Yep - they look similar - Mine has had 8 thou off it from that pic though but it din't look much different - I wonder if there is a measurement we can do externally to work out how much has been taken off from standard? (since my head is on the car now)

You haven't finished polishing all the exterior surfaces Mark - is that this weekends job

[Doug_RS2]

If you polish the exhaust ports does it completely stop the carbon build up?

And what does polishing the chamber do?

Must get a head to play with sometime

[SteveH]

That looks great Mark
I'm going to buy a spare head to go to town on soon. I wish mine had been in better condition. I can't risk removing much material due to the problems I've already had with it. Arrow shows area that has been welded. Needs a bit of a clean up.

[Doug_RS2]

Mmm - Steve - yours has had aless material taken off than mine or Marks - that machine line is in just at the edge of your valve seats - ours comes down noticeably more.

Is the 3B head the same as an ABY? Any others that are the same?

[SteveH]

Sorry...wrong picture

The crack was on the inside face of the exhaust port.
Still looks a bit crusty around the area. Pressure test was Ok though

[SteveH]

My 3B head varies a bit from end to end. The casting and/or machining runs off a bit from one end to the other. I think I spoke to Mark about this?
One end had a noticeable step in that line in #1 cyl and by #5 cyl the step has gone. I'm sure it was like this from the factory:mad:
I've blended the step out on the cylinders that had it. It's such a small amount I doubt it will make much difference to cc

[Mark Halligan]

Steve,

that looks like a good repair, would'nt know its been welded .

Doug I think the theory is that polished combustion chambers reflect heat and help stave off knocking,.........I think.

Just got round to looking at the work thats been done and I am happy with it, heres a couple of valves that have been refaced.

Mark.

[A6 AVANT]

Well!!! Nice polishing jobs!!! Do your other halves know about your skills with a duster??
Don't forget if you are looking for a nice head to play with, Mr Beetie may just have a corker of one going for grabs! Not sure what he is doing with his car at present so a PM may be on the cards if anyone interested?

[SteveH]

Nice to see your exhaust valves look rough on the stem too!

The inlets are nicely machined whereas the exhausts are ridged and nasty looking. Is this due to the sodium filled centre?

[Mark Halligan]

Is this due to the sodium filled centre?

No idea, but maybe the 'ridges' act as an anti reversal step, even if they are not designed to?

Mark.

[SteveH]

I've found that cleaning up and lightly polishing the combustion chambers helps to reduce carbon build up. This should intern, help to reduce the possibility of pre-ignition, due to glowing carbon in the chambers igniting the charge. Well, that's the way I understand it. Who knows?. It looks nice anyway

[SteveH]

Doug,

Here's the head after it was skimmed today. The shop removed 3 thou to get it flat. I'm suprised it wasn't more after the welding