Head gasket and seals - Iron head VH

[Alan G]

1958 crank cases, iron barrel and twin port iron Head, all in an 1946 chassis vh500.

I have convinced myself my oil leak is coming from the pushrod seals. I have read some posts on here about the seals being problematic - and a better solution may be to turn something to make an O ring carrier to replace the standard rubber seals - but this may only relate to alloy heads...?

So, before I dive in, I thought I would ask opinions :
Are the seals available from Draganfly good - or is the design flawed and some lathe work is preferable?

When I lift the head - what can I expect the head gasket to be? Card? Copper? And will this likely be reusable? I can heat and quench a copper ring, but happy to buy a new one if that is more sensible.

Are there other parts I should have to hand when lifting the head? I don't intend lifting the barrel as compression is good, so don't want to move the rings from thier resting place (as per the book).

Lastly - why is it DragAnfly and not DragOnfly....?

Thanks in advance.

[will_curry]

To answer your last question first there is - or was - an article on their website explaining
the name.

As far as a head gasket goes I'd just grind the head onto the spigot on the barrel as long as they're
compatible, the spigot changed in the early '50s as I remember.

The 'O' ring conversion is an alloy head thing, not iron.

It's been ages since I used pushrod tube seals but I don't remember any problems with them.

[Alan G]

Thanks Will.

Just read their 'about us' page. It comes from a wish to go drag racing; "Drag - an' - Fly"

[Simon.Gardiner]

In many years of running iron-head singles (although not in this century!) I never had an issue with OEM push rod seals - just needed to remember to use the two neoprene ones from the gasket sets in the top location. (As Will says the 'O' ring conversion is for the alloy head models.)

The OEM seals compress by an enormous amount on first fitting, maybe by as much as 1/8". These days this often gets described as putting too much strain on the push-rod tunnels causing the seal housings to collapse - but I've never had that problem (although again, using OEM components).

The spigot size on the VH stayed the same when the copper gasket was introduced for '52 (the NH definitely got a smaller spigot) so the later copper gasket can be used on the earlier model 500 but ex-factory the joint would have been ground (as was the alloy-head joint). I have also seen an engine that had been built with using copper ring gasket on top of the barrel spigot - so it's difficult to be definitive to describe what you might find when you lift the head!

Any copper gasket can always be annealed/quenched and re-used if necessary. However, as well as new push-rod seals I'd always advise having new rocker-box gaskets at hand! (Note that the rocker box gaskets always sink a lot on re-assembly, leave tappet clearance even if the book says 'nil'.)

HTH

SG

[Alan G]

Thanks Simon. I guess I'll take it to bits, then order the parts when I know what I need. Wont do any harm to be dismantled for a week while I await delivery.

[Alan G]

Thanks Simon. I guess I'll take it to bits, then order the parts when I know what I need. Wont do any harm to be dismantled for a week while I await delivery.

[paul.jameson]

When you re-assemble the engine, put a very thin smear of jointing compound on the top and bottom of the washers under the cylinder head bolts which go inside the rocker boxes. Oil running from the rocker boxes down these two head bolts is a common cause of "difficult to find" oil leaks, especially on alloy head engines.

[Alan G]

Thanks Paul. Planning on getting some Hylomar Aero (is it really worth twice the price of Hylomar Blue?) as a non setting joint compound. Good call on the head bolts.

Plan is to strip it down on Mon or Tue next week, and get parts ordered before I go away for a week, and will reassemble with new gaskets and seals when I get back.

[nevhunter]

Oil Certainly does often leak down the Head Bolts on "enclosed" motors but I suggest you don't need washers with Cast iron heads but IF you use them, Try Copper. It's frequently used where Water/oil is involved so does seal reliably. Nev

[Alan G]

I have been away for a week or so, but before going I stripped it down and have had new push rod seals and various other bits delivered.

A new question though - The exhausts (twin port) have a thin bronze bush between the pipes and the head. These are in poor condition, but I will reuse them along with some sealing paste.

The question is 'What Paste?'

All I look at on line suggest they set hard - but I want to make sure I can easily dismantle next time. Is there any non setting/non hardening paste that you can recommend? Am I over thinking this and should just slap on some GunGum? I also have a new tube of 'Stag Wellseal' non hardening jointing compound - but not sure if that is suitable for the extreme heat.

I have a pair of high level pipes I intend fitting, but will do that after I have got everything else working as it should as they will get in the way meantime, so I do expect to want to remove the exhausts in the relatively near future.