An interesting side to this diff ratio talk, I have a mark 3 superminx, for
which they reverted from the 3.89 diff back to the 4.22, (no overdirve, 3
main bearing 1592cc engine, iron head, 62hp). I think they did this sort of
thing to improve the motor magazine test results. All the acceleration
figures are improved and even the top speed was actually slightly higher.
The engine spec is identical to the previous version. However, there's no
doubt that the higher geared car is more enjoyable to drive. A magazine
review from the time states
"cruising speed is anything up to the maximum, without signs of distress
from the engine. Even 90mph can be attained easily on downhill stretches and
held for short bursts..."
and another...
"...it is most relaxing to drive at or near its maximum for extended
periods"
maximum speed 83mph, revs 5100.... eeek, what went on back in the
sixties. Did they expect to rebuild their engines every 40,000 miles? Did
they wear earplugs?
I feel rather mean running an unbalanced rootes motor for any length over
about 3,700. However, they do sometimes go into that suddently silent again
phase right up the rev range.
Greg
----- Original Message -----
From: Christopher A. Stephenson <cs_tscg(at)bellsouth.net>
To: Jarrid Gross <JGross(at)econolite.com>
Cc: Alpines <alpines(at)autox.team.net>
Sent: Thursday, 17 February 2000 08:51
Subject: Re: Overdrive & rear ratios
Thanks Jarrid. It's still running strong after 10 years and 50,000 or so
miles.
Although it does like to mark it's territory.
BTW, if anyone was wandering, it is the original engine so it is the 3 main
bearing.
Chris
Jarrid Gross wrote:
> Chris wrote,
>
> >For years, my Alpine was my only mode of transportation. At times, my
work
> >commute was long (35 miles one way). For anyone familiar with Atlanta
> traffic,
> >you know that driving fast is the only way to avoid being hit. I would
> average
> >4500 rpms to and from work. Occasionally, I would drive at 5000 rpms for
> 20-30
> >minutes at a time just for the fun of it. My Alpine is very comfortable
at
> >4500. I get a little nervous at 5000. The engine is professionally
> balanced,
> >but with no tricks. Everything is stock. It is a Series III so I guess it
> has
> >the 3.89.
>
> Wow!
>
> I wouldnt have a problem running at a continuous 4000 RPM, any reasonably
> maintained alpine engine shoulnt mind that too much, but the earlier
engine
> running (3 main) running for 20-30 minutes at 5000 RPM?
>
> Thats definately pushing the edge of the envelope.
>
> Factory engines are not well balanced.
>
> Two years ago I got a hold of two cranks and 2 sets of con rods for 1725
> engines.
>
> The con rods were cleaned and weighed, and found to be ±15 grams of one
> another.
> Pistons were also all over the place.
> Even the wrist pins had significant mass differences.
>
> Only one of the cranks made its way to the balance shop, which it came
back
> with
> a pretty fair set of new holes in the counterweights.
>
> Of course weighing all these was only an excersize becuase only the crank
> was used.
> The rods were swapped out for carillos, and pistons alla J&E, all of which
> were
> dead nuts weight matched.
>
> I'd say if anyone else out there wants to run continuous 5000 RPM on a
pine
> motor,
> make sure its professionally balanced like Chris's.
>
> Jarrid Gross
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