[Healeys] +Compression ratio

[John Rowe]

Keith 

I did that in the 60s when I had my BN1- used Dodge pistons with the skirt cut off. Worked well with a lot shaved off the head so had water squirting out everywhere. Used to run 1 gallon of methyl-benzine with 4 gallons of super. When I rebuilt my present BN1 I got some flat tops from JP (or JE) pistons in Adelaide. I reckon it would be 10:1 or so, I’ve never really worked it out. With a Wade cam,1 ¾ SU’s (HD6s) & extractors it goes like the clappers. Torque is ridiculous and runs well on 95 ULP. 

Both sets of pistons came to the top of the block. IIRC, the Dodge pistons had smaller gudgeon pins so they offset drilled the pistons because the standard ones would be below the top

Cheers

John Rowe

Qld

BN1 BT7

 

From: Healeys [mailto:healeys-bounces at autox.team.net] On Behalf Of Keith Taylor
Sent: Saturday, 16 January 2016 2:04 PM
To: Wilko2
Cc: healeys
Subject: Re: [Healeys] +Compression ratio

 

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> 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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