Valve clearance

[chris jane]

Hi anyone tell me the correct valve clearance on a 1954 vha many thanks

[adrie.degraaff]

Depending on wich pushrods you are using, I do it on sound and feeling but 0,2 mm for inlet and 0,3 mm for outlet cann't be much wrong.

VHA is very noisy but if you hear them its good.

With these modern fuels you need to check more.

[nevhunter]

If you don't know whether it has alloy or steel pushrods, you can't use the factory settings with any certainty. Set what Adrie says run it and check it hot. If it is opening up too much reduce the clearances. I find they generally open up as they get hot. As long as that happens I set the inlets with practically nothing and the exhausts at .004" The risk with running large clearances is the sudden slap you get as they open, if they are wider than the ramp. Nev

[david.anderson]

1954 is the year that Ariel introduced quietening ramps to the cams which necessitates greater tappet clearance. The new VH cam was part no 1750-54F. The VHA was probably fitted with the VH cam (but may have been fitted with the VHA scrambles cam). For the VH cam Ariel specifies .006” inlet measured when the exhaust valve is just starting to lift, and .008 exhaust measured when the inlet valve just closes, as tappet clearances. Setting the clearance as described, (rather than at TDC), sets the follower at the top of the base circle, before the ramping commences. Given the ramps of the cam are around 50 degrees of engine rotation, I would not set any tighter than the factory figure unless steel pushrods were being used. The steel pushrod expands less than the aluminium cylinder.
David

[chris jane]

Many thanks for the info its tappet time at the weekend

[Ian.Taylor]

I think it was 90 the last time I had the VHA top end off and after reading this sometime ago I always wondered what mine had for pushrods.
Last year I had the chance to find out while fixing 3 barrel studs.
Turns out mine has the alloy push rods with clearance set at Nil &.002
This setting has always worked fine with never an issue.
Somewhere else I read someone stated the VHA should have steel pushrods. I seriously doubt the original owner of my VHA swapped out the pushrods.
The bike also had the Low compression piston and still STD

[paul.jameson]

The alloy barrel should expand as much (or maybe a bit more than) as alloy pushrods (approx) so 2 thou inlet and 4 thou exhaust should be safe. If you use iron pushrods the barrel will expand more than the pushrods so nil and 2 thou will exapnd to much more with consequent rattles.

[nevhunter]

I would think an alloy barrel and head would require alloy push rods. The VCH runs them but it's head and barrel are of electron. A magnesium alloy is even more important as the coefficient of thermal expansion is higher than the normal alloy. A fair bit of hot oil comes down on the exhaust pushrod once the engine reaches operating temp. It's not good to lose clearance on the exhaust, and some "stainless" (Generic name for many questionable steel alloys) valves expand quite a lot so the original "factory"clearances may need modification to get the optimum situation. Get your motor hot and remove the exhaust cap and place some rag there to stop the oil splashing,( if that matters) and runup a hill shut the motor off and fairly quickly check the clearance existing. Do make sure the valve lifter is not affecting it and adjust later for the change you require. If you think .006" is ideal and you get .003" reading adjust your existing cold reading by the difference, later. If you take very long doing it after the engine has stopped the valve may cool somewhat relatively quickly especially if it's on compression as it will be seated and heat runs out into the head. You are trying to establish what RUNNNG clearances it has. Some engines are done with the engine hot and running. Bit hard on feeler gauges and oil everywhere and it's not on load, but you can't cover everything. Nev.