Spitting Hunter

[R.Herman]

I know that oil discussions are a can of worms. Thanks for the warning about low-zinc oils and viscosity recommendations.
In searching online I am having difficulty finding single-viscosity oils available (here in the US) with ZDDP levels in the +/- 800 ppm range but lower than 1200. But I'll keep doing the research.

I did have the barrel honed when I replaced the rings. One thing - Draganfly mistakenly sent me a set of rings with two compression and one oil scraper, the latter I could not use because I have a piston with lands for three compression rings. So I used one of my old rings with the two new ones, for what that's worth. End gaps are within the specs, as is piston to cylinder clearance.
As for spitting back/valve timing: I too cannot see how that can happen unless the intake valve is open when it shouldn't be. Seems like basic physics.
Is there a known history of mis-marked cams? If the two marks line up and are in the correct place, the only way to adjust valve timing would be to move the cam a tooth at a time, of course.
Another puzzle: my oil Clymer manual calls for nil clearance on the intake valve, and a couple of thousandths on the exhaust valve, but the Ariel Owners Guide I found online calls for 0.006 and 0.008.
Any thoughts on that disparity?
Again, thanks for the knowledgeable advice. I have a 60-year history of fettling British, European and Japanese motorcycles, but this is my first Ariel and your experience with this model is most helpful to me.
Bob

[paul.jameson]

Your photo provides what I think is the answer. You carb float chamber is the wrong one. Its top should be level and sides vertical. There are float chambers with different angles of the connection to the main body of the carb to suit the different inlet tract angles of different bikes. With yours so far wrong, the float will be sticking and your fuel level too low, causing a weak mixture.

[paul.jameson]

Float chamber angle should be 15 degrees, according to the Drags website which is almost certainly correct.

[simon.holyfield]

Paul's right - my W/NG uses this one, which puts the float chamber in the vertical position when fitted:

https://amalcarb.co.uk/pre-monobloc/74- ... ipple.html

You can pick them up second hand for a lot less!

[R.Herman]

Well, if it ain't one thing...
I have a spare float chamber, I'll check to see if it is different.

[Pete.Silson]

Another puzzle: my oil Clymer manual calls for nil clearance on the intake valve, and a couple of thousandths on the exhaust valve, but the Ariel Owners Guide I found online calls for 0.006 and 0.008.

0.000" inlet and 0.002" exhaust is correct for an all iron engines. The 0.006" and 0.008" are for the later (1953 onwards) alloy head engines.

[R.Herman]

The plot thickens: having found and fitted the correct float chamber, which now is oriented vertically (thanks for noticing, Paul) I was perusing my Clymer manual and in the section describing camshafts, I read that for 1951 Ariel changed the cam and followers to a system with one-piece cam and a forked exhaust follower/lever with the inlet valve follower fitted inside the fork.
My bike is titled as a 1948 model and the chassis number agrees with that, but my engine has the above-mentioned cam and followers.
According to Clymer, that setup results in different valve timing from the early system.

[nevhunter]

Not enough timing variation to be worried about. It wears better and is generally quieter but for racing stick to the small base 2 lobe cam Original VH Valve springs tend to be TOO strong and strain everything. Nev

[R.Herman]

I did read that the later version improved durability. Always a good thing.

[Simon.Gardiner]

Potentially, this introduces another factor.
The single lobe cam comes in two standard varieties, the one for the later alloy head models has quietening ramps and are used with the bigger tappet clearances. If you've got a cam with ramps and you're using zero tappet clearance the inlet valve will be getting opened (albeit slightly) early - that could be the source of the carb blowback.

(On a another, that front brake lever is at too much of an angle, it should be making a right-angle with the cable when it's full on. Experiment with the fulcrum adjuster and maybe move the lever to a different position!)

SG