Problem lapping head to barrel on a '54 VH500

[dennis.t]

I am new to Ariel's so please bear with me.
I bought a re-conditioned alloy head from Drags for my '54 VH500 (at great expense) as my engine did not have one. I now find that the spigot on the cast barrel is much higher than the corresponding recess in the head leaving a gap of about 0.7mm between the mating faces. Will it be possible to use grinding paste to get the mating surfaces together? It seems a lot to grind by hand.
Some information about the head. The valves are the same diameter and the exhaust fitment appears to be the push-in type. I have no exhaust downtube yet to confirm the fitment.
I should welcome any advice.
Dennis

[Simon.Gardiner]

I'm not fully 'converted' yet - I think that's about 30 thou to get rid of.
It's a lot but I think I had 40 thou to deal with when I swapped cylinder barrels on my '56 a few years ago.
'Just' hard work (and finish up with fine on the inside 'spigot' and coarse on the outer surface).

I'm a bit uncomfortable about the push-in pipe with the same-size valves, I thought that by the time the pipes became push-in the exhaust valves were smaller. Maybe the head's been reconditioned with the earlier (bigger) exhaust valve. Probably not an issue as long as you remember that it needs the earlier size should you need to get a replacement!

SG

[dennis.t]

Simon,
That's good to know. The valves and springs are new, as supplied by Drags so they look OK. The valve heads are about 1.7 inches (43.4 mm) in diameter.
I have no exhaust downpipe so your advice is welcome. Does anyone know what the outer diameter of the "earlier" downpipe is where it pushes into the head? The inner diameter of the head stub on mine is about 1.8 inches (45.6 mm).
Dennis

[Simon.Gardiner]

Dennis
You buy whatever the appropriate pipe is for the head without having to specify a diameter (unless you're intending to make a 'special').
Alloy heads are either push-over stub (this is the 'earlier' one, '54/'55) or push-into head (1956-on). (I'm ignoring the early '50s VHA and VCH heads 'cos I don't think Drags would sell you one of those without telling you it was a bit 'unusual' and you'd know if you had one!)
If you've got a 'push-in' head I'm not sure why you're interested in the size of the pipe for the earlier 'push-over' head (and also the 'push in' pipe is longer at the top, too).

SG

[dennis.t]

Simon,
Sorry for the confusion. I thought you meant that there are two sizes of push-in exhaust pipe. Looking at Drags website there is only one push-in pipe listed (no diameter specified) for the '54 VH500 so hopefully I can use that part number when I buy one.
Dennis

[JohnnyBeckett]

hi i put my barrel on a surface grinder and then gave it a light lap by hand to finish off

[Simon.Gardiner]

Dennis - just look for the push-in head being the '56-on pipe, even if the rest of the bike is '54 !!

SG

[Pete.Silson]

Armours list a pipe for 56 on VH:

https://www.armoursltd.co.uk/product/a7 ... swing-arm/

Pete

[Julian Murphy]

I always thought that the spigot should be 'taller' than the counterbore in the head.

The spigot and head should bed together, leaving about a 0.75-1.0 mm gap between the head and barrel face to torque down on, being as it is a non gasket make up.

I skimmed my head, by a few thou (oops mixing metric and imperial in this post) to ensure that the gap was equal at 4 positions.

I made aluminium collars to hold viton o rings instead of the rubber sleeves for pushrod tunnel seals.

Look up the thread NH refresh.

https://forum.arielownersmcc.com/viewto ... 6&start=10

[charles.bulloch]

The factory owner's guide does not ask you to lap in the cylinder head on these models.