1930 V ignition timing

[Bob Appleton]

Just wondering if anyone has experience timing the 30V or 30VC.
Shop dope 260G July '47 states that these models use a 1/4" - 5/16" BTDC, front cly on compression stroke.
This is unlike the rest of the 31 to 36 V series.

Thank-you

[Steve Slocombe]

Dear Bob, Shop Dope 51C of 14 Nov 1929 says ignition occurs 5/16" to 3/8" btdc and 1/4" to 5/16" btdc on commercial models, so I think differences are due to compression ratio and improving gasoline octane over time. The 1947 advice is to time a shade more advanced than the 1931-36 timing marks. These days we have much better gasoline, and there is plenty of adjustment on the advance/retard twist spiral, so I'd follow the later advice even for 1930. You can tell when the carburettor and ignition are dialled in when the bike slows down with retarded ignition and speeds up with advance.

[Bob Appleton]

Thank-you Guru Steve.
Prompt and excellent answer as always.