valves appearance

[eugenius]

Hi all, I have tried to decarbonize the cylinder head after changing the piston rings of my BSA A10 (I have mounted the +20 size as adviced) and I have noticed these streaks above the flat side of the valves. Is that normal? I have also noticed that both left sided valves are marked with an A whereas the opposite ones do not  .  I send you an image in attach. Thanks

[berger]

eugenius try a magnet on the valves normally inlets are magnetic exhausts are not

[RichardL]

I don’t have a clue what the “A”s stand for. Maybe Julian has documentation on it. The scratches in the valves appear to be something like the use of a die grinder (Dremel) to remove carbon. I don’t think that would fly in a high-performance engine, but for weekender puttering, it probably won’t matter. The thing that gets me is the out-of-round cutaways at intake valves that seems like a mistake that was made, possibly while  cutting for new valve seats. Maybe others have seen this before and will say it’s normal.

Richard L.

[eugenius]

thanks Keith I'll try the magnet; and thanks Richard for reassuring about the streaks. I will try to dismount the valves to check behind as soon as I will find a spring compressor that may work better of the chinese one I have bought recently and which bended when trying to use it (no way to reinforce it, i have tried twice with no success); a really chip and anuseful tool . A nice we

[eugenius]

Great Keith! I have applied the magnet and actually both inlets are magnetic both exhausts are not. They seem placed properly. Thanks again

[RichardL]

The scratches in the valves appear to be something like the use of a die grinder (Dremel) to remove carbon. I don’t think that would fly in a high-performance engine, but for weekender puttering, it probably won’t matter.

Let’s see if others think the scratches are more serious than I’ve implied. Maybe they need to be blended-in  (without going any deeper) to avoid hot spots, or possible points for cracking.

Richard L.

Richard L.

[limeyrob]

Not ideal but I would run it.  What compression are you running?

[sean]

also curious about the centre punch marks look like 3 on 1 side and 2 on the other  .....I would pour a bit of gas on intake and exh ports see if it leaks past the  valve seat , looks like someone used a dremel or die grinder on the valve face

[eugenius]

Thanks for replying. I don't know exactly the compression of my engine but should be that of a normal BSA A10 road rocket engine 7,2:1? The engine has been probably replaced in the years 60' the serial number is DA10 R 9027. I put in attach an image.  Regarding the number of possible marking signs on each valve that's strange but possible. It seems a little too much just to mark a valve. Nonetheless thanks a lot for the advices, I would try to check if there is a leak.   

[Swarfcut]

    Is it me or do those valves look a little low in the inserts? Almost "pocketed" as we used to say. Reckon it needs further investigation. Valves can be refaced, but taking away too much material reduces the diameter, so they may be the correct valves, but not true perfection. Same goes for recutting the seats. Bare minimum of material removed to restore back to an unbroken seal.

   Odd marks, dots etc are probably of no consequence. Quality valves from times gone always had some makers' mark. BSA stamped the heads with the part number, JAMES and ALPHA marked the stems.

 Try  ALPHA BEARINGS    http://www.alpha-bearings.com/Valve%20cat/valvehp.htm   for a replacement valve catalogue,

 Drags also have a valve chart with stem, head, length, OE part number. Takes some finding but it's in there somewhere.

 Swarfy.

 PS When using a valve compressor to dismantle a head, tighten it up until there is some pressure on the valve cap, then give the valve spring compressor fork on the cap a smack. This will break the bond between the valve collets and the valve cap......then all the compressor has to do is compress the spring and if it can't do that it really is crap. Save your energy, let the hammer do the hard work.

[eugenius]

thanks Swarfy, indeed I have few experience and I will try as you advice with a hammer smack to dismountle the valves. We'll see
Eugenio   

[limeyrob]

The inserts do look pocketed, but I'm confused as the ridge is not where you would expect it from wear or grinding.  The reason I asked about compression ratio was i was curious about the state of tune.  If its soft there's no point in doing a lot of work to do a triple angle on the valve seats.

[muskrat]

G'day Eugenio.
Looks to me as if the previous owner put standard A10 valves instead of the larger Super Rocket valves. Can you give us a pic of the valve springs & collets (they are different). The left spark plug hole has been fixed with a "Timesert" almost touching the inlet valve seat 
Cheers

[eugenius]

Hello friends, Thanks for the insights! Yes indeed the impression is that smaller valves have been pocketed in a wider housing. I continue to learn a lot from all of you and that's great. Here's an image of the valve spring and collets. Now the problem will be should I change the valves or not and if yes the normal or the large?
Eugenio

[sean]

big valve intakes are 1 1/2 inches dia  ...