The EN40 crank was used in the thin-flange 1275 blocks.
EN16 cranks were used in the rest of the spridget motors.
Many racecars are built with EN16 cranks. They will last
a *long* time if the motor is balanced and you keep it
below about 7200 rpm. Try and make it a 0/0 crank or a
10/10 crank if you plan to rev it out like this.
I've been using the same EN16 crank for 4 or 5 years of
competition and the previous owner also did a few seasons.
I've kept it to below 7200 except on 2 or three desperate
occiasions where it went to 8000.
There are folk who regularly use 8000 or more with the EN16
crank and they seem to get a season or two out of it before it
either fails or is retired after a crack-test. Those last revs seem
to make all the difference to reliability and life.
If you find a good EN40 crank, then that's great, but
the EN16 crank is pretty good too.
Just get it crack tested when you build the motor and it should
be hunky-dory
Mike
----- Original Message -----
From: "Jon Paschke" <birdman@lightspeed.net>
To: "thicko" <team-thicko@autox.team.net>
Sent: Monday, January 17, 2000 3:39 PM
Subject: crank shaft
> Cheating dogs,
> I have a question about cranks for 1275's. In the book I am reading on
> tuning he mentions a EN40B crank being the better unit to use. Are these
> nitrided cranks really better and are they obtainable? At what cost? The
> author also says that the stock Midget 1275 cranks are pretty tough
> themselves so what's what? I am building a hopefully, fast street, road
> motor. What about doing the 73.5mm overbore on a 1969 Midget block - it
> needs boreing anyway, maybe a sleeve even to get back to standard oversize
> so not much to loose here. Someone who has been there before give me a
> little heads up on this.
> I want to build a nice fast motor - once -
> TIA
> Jon
> 58 Sprite
>
>
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