Ignition timing and tightening torque / Ariel 500 VH 1954

[Chris_Normandy]

Subject : Ignition timing and tightening torque / Ariel 500 VH 1954 (aluminium cylinder head)
Member arielownersmcc no 7851 - Apr 2023 -
Txt :
Good evening to all,
Sorry, I don't speak English very well.
I am writing from Normandy in France.
I would like to ask you, the members of the Ariel Club, a few questions.
I am in the process of restoring or rebuilding a 1954 Ariel 500 VH motorcycle - Engine no. PD 394 - Frame : KS - Gearbox no. : GB6.
This is a cast iron cylinder engine with an aluminium cylinder head. I had the cylinder rebuilt at a local garage. I replaced the piston and the 3 rings (bought from Club Ariel).
On the aluminium head I replaced the 2 valves and new valve guides which I bought from Draganfly.
First question: How many inches or millimetres should I allow before top dead centre (TDC) for the Lucas M01 magneto at full advance?
Second question : Tightening torques for aluminium cylinder head bolts and studs. What torque should I use for the 5 nuts? How many daNm?
Thank you in advance for your answers.
Christian - Normandy - France

[Brian_Walker]

Your timing will be 1/2" before TDC, check the points are 0.012"- 0.015" first. No set figure for head bolts just firm with a normal length wrench.
For high compression engines make timing 5/8" BTDC.

[keith.mettam]

Here is a copy of an Ariel factory document dated 1958 that gives torque figures, just convert them :-

Ariel Torque Settings.doc

(805 KiB) Downloaded 471 times

Best wishes,
Keith.

[Chris_Normandy]

Good evening to all,
Good evening Brian and Keith,
Thank you for your answers.
I now have a better understanding of the ignition timing on my 500cc engine.
And thanks also for the explanation of how to tighten the cylinder head nuts.
Bye from Normandy (France)
Regards
Christian

[david.anderson]

Every alloy head that I have come across has had stripped rockerbox threads, and some have had dodgy helicoil or timesert repairs. The figure quoted by Ariel of 210in/lbs or 17.5 ft/lbs seems excessive to me and also exceeds what would normally be used for a 5/16” bolt. I only torque to 10 ft/lbs and have never had a problem.
David

[Chris_Normandy]

Good morning everyone from Normandy,
Hi David,
Thanks also for your reply regarding the tightening torque for the Ariel 500cc VH aluminium cylinder head.
Regards.
Christian