I have a Wizard Super 5, Ser #938595 and marked on the plate as a Model WH-6. The tech info page shows any Ser # above 931751 as a Model WH-6A. Any ideas about this inconsistency and what is the difference between a Model WH-6 and a WH-6A?
Below is the resource I used to help compile the serial number model year list.
I don't have a perfect answer for you, but the WH6 and WH6A are based on Mercury's Mark 6 and Mark 6A. Even though the Wizard's were rated as 5HP, I believe they are closer to 6HP. The Mark 6 was rated a 5.9HP and the 6A was given a full 6HP...I'm sure a negligible difference. Also, the 6As also incorporated the Beddix Scintilla magneto system, and I think the 6s only used the Phelon magneto. Bottom line, is that I don't think there is a dramatic difference other than the magneto. Make sure when you are buy parts to get those for a 6A, as some of the parts will be different (not all, however).
Hope this helps!
Mercury was largely Elmer Carl Kiekhaefer.
The company was very closely held and not listed
on an exchange. Except for bank and a few shareholders
production,sales,profit numbers were not given out.
Production figures for early models are hazy, postwar
numbers indicate the serial number range a model
is in NOT total production. The inconsistancy you
note is likely the use of the what was in the
"parts bin" when your motor was built.
Mercury was similary stingy with numbers in the
Service Manual...mechanic was advised to check
used crankshaft for wear by comparing to a new
crankshaft...kind of difficult unless you were
a Mercury Dealer with part in stock.
Mr. Kiekhaefer tried to keep Mercury Dealers
from seeing lower price Wizards as competition
by making a different less glamorous line for
Western Auto...apparently with incomplete success.