[Healeys] Compression ratio for a fast road 100

[David Nock]

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

www.britishcarspecialists.com
.
.

On Jan 13, 2011, at 7:23 AM, Thomas Willig wrote:

> Hello,
>
>
>
> I am in the process of rebuilding the engine of my 100. In order to  
> get
> some more punch from it, I am thinking about fitting DW forged pistons
> with an 9,5:1 compression ratio.  You all know that if you talk to  
> three
> people (all of them not A-H 100 owners) you will get at least four
> different opinions. Statements given were:
>
>
>
>
>
> "You will get detonation at this compression rate"
>
> "You will loose all smoothness of that engine"
>
> " A motor with that CR is only drivable on the track"
>
> "You will have to buy three head gaskets every year"
>
>
>
> I am aware that most of this is probably nonsense, but... maybe..??
>
>
>
> I guess there must be experienced folks on the list who are running
> engines with a 9,5:1 compression ratio. Please come forward and share
> your experiences and thoughts with me.
>
>
>
> Regards
>
>
>
>
>
> Thomas Willig
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