Vh followerr to HS ?

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Ian.Taylor
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Vh followerr to HS ?

Post by Ian.Taylor »

I'm curious to know if a 51 on VH follower can be converted to HS spec?
Thanks
will_curry
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Re: Vh followerr to HS ?

Post by will_curry »

Draganfly offer a conversion - see

https://draganfly.co.uk/product-categor ... ottom-end/

Obviously to get any benefit you'll need the appropriate scrambles cam and piston. The modification
to raise the oil level in the cam chamber is well worth doing too. Finally, the exhaust valve in the iron
head is too large to be safe with the Mk1 setup in my opinion.

I'd be careful fitting an HS cam into an early all-alloy VHA or VCH too as the cylinder base is not that
strong. The alloy barrels fitted to the scramblers have a much reinforced base flang.
Ian.Taylor
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Re: Vh followerr to HS ?

Post by Ian.Taylor »

Thanks for the reply Will
I have a 53 VHA which I plan on using the MKlll cam and 7.5:1 piston which I have been running since the late 90's
I have no plans to install the 9:1
The base is held down by 5 studs and is 3/4' thick
I have near new VH followers which will work but the HS inlet I'm told is preferred , that is the route I would like to go.
I do have a badly worn VH follower I would like converted to HS.
Good to see Drags does the conversion.
david.anderson
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Re: Vh followerr to HS ?

Post by david.anderson »

All single cams can be run in an iron head without any risk of hitting the piston, provided proper valve springs are used. In the case of the mk3 cam run with HS inlet and VH exhaust followers (the correct set up) the inlet valve is lifted .105” from the seat at tdc whereas the exhaust valve is only .091” lifted from the seat. So the inlet valve is .014 closer to the piston.
In the case of the 56mk1 cam (run with HS followers) the inlet valve is lifted .170” off the seat at tdc whereas the the exhaust valve is lifted .155” off the seat at tdc.
To put a valve through a piston generally involves the valve head separating from the stem or the use of the wrong spring in which case the valve is lofted over the top of the cam. The standard VH VG spring VS422 is not suitable for mk1 cams as it is too light and the valve will loft and bounce. It may also be unsuitable for mk3 cams.
David.
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