> Your MGA is a Mark II, which would have the 1622
> motor and a 4.1 rear
> end. Certainly a better ratio on the highway than
> the earlier MGA's, but
> not quite a 3.9 of an MGB.
>
> > I know I can travel at 70-75 mph all day long at
> only @ 3600 - 3800
> rpms.
>
>From this information, if you go from a 4.1 to 3.9,
you'll save a whopping 175 RPMs at 70 MPH. Larger
diameter tires will net more overdrive effect than
that. But there may be other benefits to the swap
(strength? reliability? parts availability? etc.?).
Increased load = increased wear. At lower RPM's, the
load per revolution is increased compared to higher
RPM's, so the savings in wear is non-linear. I'm not
saying the engine won't wear less at lower RPM's, I'm
just saying half the RPM's isn't half the wear. There
are always trade offs. For example if you gear it up
so much that you have to rev it up to 200 RPM's to
take off, you be going after a new clutch instead of
rebuilding the engine. Also, super low RPMs are hell
on bearings and cams. 6 of one 1/2 dozen of the other.
I say go for what's most fun for you.
jon
=====
77 MGB "Christine" slowly, but surely healing, rubber buckers, uh burry bumpys,
rubber rabie bufer lubbers. !@#$ it: black cow catchers
58 Willys CJ-3B, the Killer-B
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