VH alloy head push rods too long?

[dennis.t]

I have a '54 VH500 that I bought without a head. I purchased an alloy head from Drags but when I came to fit the rockers today the push rods seem to be too long. There is no clearance between the rocker adjuster and the valve stem (with the hardened valve cap in place).

My suspicion is that the engine originally had a cast iron head and the push rods are longer for that arrangement. Can anyone shed any light on this?

Drags seem to be out of stock of push rods so my next problem may be where to get shorter push rods. Is it possible to shorten the ones I have if the ends are removable?

Many thanks,
Dennis

[will_curry]

According to DraganFly's website the all-iron 500 did indeed have pushrods 1/8" longer
than those with alloy heads. Another difference is that the all-iron 500s had steel
pushrods while all the others had alloy pushrods.

The ends of the pushrods are simply pressed onto the tube and in my experience
can be removed without damaging the tube itself.

[Simon.Gardiner]

If the engine was originally iron head it'll be pre-1954 and it'll only have 4-studs for the barrel, the alloy-head engines have 5.
Maybe the problem is that it's using an earlier twin-lobe cam with a bigger base circle?

HTH

SG

[Roger Gwynn]

It is the cam that determines which length of push rod to use. Identify the cam, see the models and years it is used in Draganfly's listing and use the push rods listed for those models. Aluminium expands much more than iron so if you use the wrong material the tappet gaps will either close up or increase. A 54 VH should have had an alloy head and five studs to the crankcase.

[dennis.t]

Thank you for your replies.
I should have mentioned that the push rods are Aluminium, the head is a five-stud type and the barrel has enclosed push rod tunnels and is also a five stud. Not sure about the cam. The seller said it is a 'high lift' cam but I have nothing to compare it to. The timing case is assembled so if I can avoid taking it apart again I will.
Can I simply cut the push rods to the required length i.e. 11 and 5/16ths as specified by Drags? Or is it imperative to determine the cam type first?
Lastly, should I heat the push rod ends to aid removal?
Many thanks,
Dennis

[will_curry]

I don't think it's imperative to determine what the can form is - that can come later.

If the pushrods are aluminium I'd expect then to be the correct length anyway.

As far as I'm aware the only 'wild' cam with a larger base circle (A6/664) was a twin-lobe
cam and you might just be able to see with a torch down the pushrod tubes in the barrel.

To get the ends of fan alloy rod put it in the freezer rather than heat the ends.

[dennis.t]

Will,
Many thanks. To be honest I am not sure what a twin lobe cam looks like? I looked at Drags cam options but that didn't enlighten me
Good tip about the freezer.
Dennis

[nevhunter]

I can locate a set of alloy push rods for that year engine and measure them if it helps you. The originals should be ok for the largest base dia cams. Someone could have made longer ends for some other reason. Ie smaller base dia cam. Nev

[dennis.t]

Nev,

Many thanks for the offer but I am sure my rods are too long. I am going to cut them down and see how I get on. If I fail I will take up your offer with a view to finding another set.
Dennis

[simon.holyfield]

Have a look at this - you can clearly see the two lobes on the A6/664 cam on the left.

Later engines use a camshaft where both valves are operated by one wide cam.