[Healeys] +Compression ratio

[Larry Varley]

Rick is quite right, and flat top pistons level with the top of the 
block was the way it was done years ago for racing, very problematic 
with modern fuels in a road car. The semi dished 100M style piston works 
well and give a bit over 9 to 1 compression.
Cheers
Larry Varley


On 16/01/2016 3:04 PM, Keith Taylor wrote:
> Thanks Bob & Rick  I believe the pistons were from a Dodge "Q" & are 
> not dished, they are level with the top of the block
> They were fitted long before I bought the car & after rebuild I had to 
> fit a high torque starter to get it to turnover
> From your assessments & my assumptions I thought compression would be 
> higher than 9.5 possibly 10+
> The car certainly has plenty of torque  It also had an ugly/bizarre 
> plumbing setup to the head similar to a 100S for cooling
>
> Curiosity satisfied
>
> Keith
>
> On 16 January 2016 at 12:57, Wilko2 <e-wilkins at cox.net 
> <mailto:e-wilkins at cox.net>> wrote:
>
>     The standard 7.5/1 piston has a dish top with a volume of 29 cc.
>
>     The LeMans 8.5/1 piston also has a dish top but the dish is not as
>     deep being only 14cc volume. A true flat top if it has the same
>     compression height (distance from the top of the pin hole to top
>     of piston) would give a ratio of 10.5/1. There could be design
>     variations that are flat top but have a lower compression height
>     which would give a lower ratio.
>
>     Without knowing where the top of your piston is in relation to the
>     top of the cylinder or dimension from pin, there's not way of
>     knowing without measuring your chambers.
>
>     Rick Wilkins
>
>     On Jan 15, 2016, at 5:10 PM, Keith Taylor wrote:
>
>     > What would be  the compression ratio of a BN2 fitted with flat
>     top pistons.
>     >
>     > Keith Taylor
>     > BN1
>     > BN2
>     >
>     > Southern Highlands OZ
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