5 degree Mac flywheel

[ted johnson]

Ok, Tom, Steve and the other gurus. Is there a fool-proof way to POSITIVELY identify a Mac standard engine series (Mc5 thru Mc93) 5 degree flywheel without making a fixture to determine the keyway VS. magnet position? In the early sixties, we weren't concerned with this as the 5 degree wheel hadn't yet appeared. Any casting markings? I'm positive that this has been discussed before, but I can't find it! Thank you. Ted

[Rob Voska]

Piece of long keystock held in a vise. Hang flywhees in line by keyway & use a straight edge to see what magnets are where. Simple & cheap!

The 5 deg usually has a 5 on the raised boss..... but that don't mean it's a 5 deg as they are all over the map!

[david a luciani]

ted,
the way i can tell is by looking at the keyway and lining it up with the little cast arrow below.
if it's a five the slot is a little behind the little cast arrow counter clock wise.
if it's a regular the slot is a little past the little cast arrow clock wise.

or it may be vise versa i usually take a know one to be sure.
the stamped in five is usually one that little nub like rob said but it also can be stamped just about anywhere.
many of the stamps i've found after media blasting them to clean up the years of dirt or nasty paint.

dave

[Jeff Campbell]

Ted,
Look at this last page of this ... is shows the way to tell them apart



Rob's method is great for sorting through a bunch of flywheels quickly ... if just looking at one, as Dave said, you can eyeball it just as is shown in the document above.

Jeff

[ted johnson]

Thanks, guys. I'd heard about the casting mark, but looking at about 25 wheels, we found several that had a 5 on them, but the keyway doesn't look as though it is positioned differently. Mine has a 5 steel stamped into it, but it looks as though the stamp is original, not added. Rob's method is the one we figured to be the easiest. Later! Ted