[Healeys] Compression ratio for a fast road 100

richard mayor mayorrichard at hotmail.com
Fri Jan 14 18:24:09 MST 2011


The 6 cylinder flywheels are  28-29 pounds.

Richard Mayor
BN7L-466  Vintage Racer
Portland, Oregon




> Date: Thu, 13 Jan 2011 22:19:50 -0500
> From: pennell at cox.net
> To: healeydoc at sbcglobal.net; twillig at ruda.de
> CC: healeys at autox.team.net
> Subject: Re: [Healeys] Compression ratio for a fast road 100
>
> All,
>
> When I had the fly lightened for my BN7 I went to my machinist.  He was a
Mini
> racer and had experience on lightening flys on many race cars.  He cautioned
> against lightening too much.  The nasty part is the fly could fly apart
under
> hard driving, becoming flyiing bits of shrapnel and tearing up legs.  He
reduced
> mine to 17.something lbs.  Runs smoothly and revs quickly.  Feels real
peppy!
>
> Anyone recall the orig weight of the 6 cyl fly?  I want to say 22-23 lbs.
>
> Keith
>
> ---- David Nock <healeydoc at sbcglobal.net> wrote:
> > Be very careful when raising the compressions on a 100/4. We just
> > finished re doing a 100 M that had 13:1 flat top pistons in it the
> > engine would run on and ping so bad on street gas that you could not
> > drive it. Also due to the high compressions it cracked that crankshaft.
> >
> > DW only shows a 8.5:1 and 10.5:1.  I would say that with the 10.5:1
> > option you will have to be very selective on fuel and possibly be
> > limited to race fuel.
> >
> > When we are building a performance motor for the street we will use
> > the 8.5:1 pistons with a good performance camshaft, New lightened
> > flywheel and an aluminium head with hardened studs and special head
> > gasket that does not LEAK. We also will use a verneer cam gear to
> > adjust the cam timing to the optimum performance.
> >
> > We have installed lots of light flywheels on both 4 and 6 cylinder
> > cars. As low as 15 lbs and had no problems with idle, accleration or
> > any other of the things that have been mentioned on previous e mails.
> >
> >
> >
> > David Nock
> > British Car Specialists
> > Stockton Ca 95205
> > 209-948-8767
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