[Healeys] Compression ratio for a fast road 100

PG britishcars at shaw.ca
Thu Jan 13 23:07:29 MST 2011


The lightened steel flywheel I purchased from AHealey Spares is
15lbs.....when I weighed the old one it was 36lbs.

This was from a 2.9 litre engine

-----Original Message-----
From: healeys-bounces at autox.team.net [mailto:healeys-bounces at autox.team.net]
On Behalf Of pennell at cox.net
Sent: Thursday, January 13, 2011 7:20 PM
To: David Nock; Thomas Willig
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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