valves appearance

[limeyrob]

The head number is just visible in the pic, looks like 67-1120 or is it 67-1126?

[Swarfcut]

 There is something not quite right here, but using the sources I posted you should be able to identify the valves and whether they are the correct parts or the previous owner's best guess. A smaller valve head will obviously sit lower in the valve seat, but as long as the seal is good the engine will run but not achieve the performance you could get with all the right bits.

 Alloy head uses different valves, caps and collets from the standard iron head engine. Alloy head  collets fit a narrow groove in the valve stem, standard valves have a much wider groove, so easy to tell if at least they are the correct type.

 Alloy head valve stem shown below, this is actually an aftermarket ALPHA valve V128, Super Rocket Exhaust.

 But Rob's added a further conundrum. The head casting number 67 1120 is  the basis for a Shooting Star 500cc, with 66 mm bore. So
 measure the combustion chamber and compare with the bore....all may not be as it seems. For an A10 you want 70mm or thereabouts.  67  1126 is more like correct, 56/57 Road Rocket.*

 Swarfy.

 *Casting numbers differ by a few digits compared to part numbers listed as complete assemblies, cylinder heads being a case in point.

[eugenius]

The head number is 67-1126 actually, regarding the valves size and codes I will check and reply, thanks a lot
Eugenio

[limeyrob]

I'm following with great interest as I'm about to rebuild my 67-1126 head.  Your problems and replies could save me a lot of time

[muskrat]

G'day Eugenio.
OK valve gear looks right. Measure the valves, should be 1.41" inlet and 1.38" exhaust.
You really need to check the valve guides before you get too deep. No good having a rebuilt motor that smokes like a 16 year old!
http://atlanticgreen.com/a10alloyhead.htm
Cheers

[eugenius]

Hi muskrat, I eventually dismounted and measured the valves. According to my caliper, inlet 1.458 and exhaust 1.380 I cannot read well the codes onto the valves it seems something like 322 VK England but I must check better tomorrow with a lens. 
Eugenio

[limeyrob]

I believe the 67-1126 head is 1.455 inlet so your measurements look correct.  I'll be getting my valves out this week as the head is on the bench, its also a 67-1126.

[trevinoz]

the "big valve" is 37mm and earlier is 36mm.
I think that Eugenius has 37mm valves.

[Macbeth]

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

So exhaust are stainless of some level ?

[muskrat]

G'day Mac.
Yes sort of austenitic stainless steel.
"The exhaust valve is usually non-magnetic.
Commonly, in modern automobile engines, intake Valves are made of a martensitic steel alloy and are magnetic. Exhaust valves are commonly an austenitic stainless steel, called “Sil1,” which is non -magnetic. Sometimes, especially in higher performance engines, especially boosted engines, exhaust valves are made of inconel, which is a nickel based super alloy. While pure nickel is magnetic, inconel alloys, due to high chromium content are typically non-magnetic."
I have used inlet valves (just for size) in a road motor but hasn't or expected to do thousands of miles.
Cheers

[eugenius]

G'day all, a lot of interesting information from a great forum! I am approaching to try dismount the valves' guides as soon as I will receive a brass bar to make a custom made instrument for the purpose. Someone say that after removal it is always necessary to rebore the valve guide seats, someone not. Any advice on this regard? Thanks everybody

[limeyrob]

In my experience if the head bores are in good condition and the guides are good quality - ie concentric and true, then a light valve grind is enough. Its easy enough to put the guides in then drop the valves in and take a look how they seat.  Don't be tempted to grind out any big discrepancy as you are grinding the valve away at the same time as the seat.  Its all well and good advising the seats be re-cut, but if the new guide is that far out compared to the old I would suspect the quality of the new guide or how its seated rather than go taking metal off the valve seats.

[sean]

G'day all, a lot of interesting information from a great forum! I am approaching to try dismount the valves' guides as soon as I will receive a brass bar to make a custom made instrument for the purpose. Someone say that after removal it is always necessary to rebore the valve guide seats, someone not. Any advice on this regard? Thanks everybody

re cutting the seat after a guide install is done because the new guide might be at a slightly different angle in relation to the valve seat you can check with layout blue on the valve sealing side and a valve lapping tool .
I used colisbro valve guides and G and S valves from SRM tight tolerances but havent had a problem with them.

[muskrat]

G'day Eugenio.
Your iron head will use cast iron guides. If the old ones are pushed out hot (200C) new oversize guides may not be needed. If pushed out cold I'd use 0.001" oversize. Best to have a very accurate "cubit stick" to measure.
9 times out of 10 the seats will need at least a lap or cut if bad.
Cheers

[eugenius]

Thanks all, I have a 67-1126 super rocket alloy head with bronze valve guides; then if I will succeed in removing I will measure them and buy the new a little oversized if I understood well? Indeed I have found a little play when moving laterally the valves particularly the inlet valves, less with the exhaust ones...