Hi Kevin
I am not sure what the compression ratio is but possibly 9:1
Then I need to calculate the change by adding double gaskets or then adding in the plate which was supplied with the kit
The plate may be overkill with the current 9:1 ratio
I think I need to do some reading

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1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Just measured the decompression plate, it is 0.070inch or 1.80mm
So will try and work out approx effect on 9:1 compression ratio

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

So with my basic maths, I'm thinking?
Current CR assumed to be 9:1
Recommended CR to be 8:1
Assume total capacity is 1342cc therefore each cylinder is 335.5cc, so combustion chamber capacity is now 41.93cc?
335.5/8 = 41.93cc
For a CR of 8:1 = 335.5/7 = 47.92cc
I'm thinking I need a chamber size of 47.92 to get to 8:1 CR?
I therefore think I need to add 6cc into the combustion chamber?
Assume head gasket = 2cc
I need the decompression plate to be 4cc
My plate is 0.070inch thick so I think the volume of a 2.80 inch bore would be 0.4312cc
Looks close to my recommended 8:1?
Any maths experts want to correct my calculations?

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

let me know if you want me to look up the name of the company that made me a 2mm solid copper gasket. 2mm was the thickest they could do and cost $80

I'm not using it anymore, but not sure if I'd trust it on another motor

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did I tell you that I won a trophy?

Most 1275 head gaskets are 4cc not 2cc

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4efte powered Clubman
supercharged 998 race car

Yes, I'm thinking that maybe 2 head gaskets might be the way to go?
But first I will do a few less dramatic options.
And if all else fails then it might be the EFI path

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Google this " minihead app"

App works well with common fields or enter your own.

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Now with 2 extra ports!

Would the fact that the carby is a mile from the head (and so far down low!) have any effect?
It doesn't seem right from an engineering sense.
Yeah I understand when it's under boost it's a different situation but with your issues at idle it just seems all too odd!!

- sure it is under vacuum still, but it's a long way to suck all that fuel up and in... i dunno... just doesn't seem like a nicely engineered kit to me.

Hey willy, no prizes for stating the bleeding obvious

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

You could always bend up some more pipe so you can stick the carburettor up higher.

I'm sure he's already thought of that Morris, but wants to try a few different things first.

You could run a customized bonnet to house the carburettor and air cleaner too if you run into clearance problems.



Tyson.

You could
Unfortunately there is very limited space under the bonnet, hence the location of the carby

I think EFI is the way to go, just need to save up again

_________________
1969 Cooper "S"
1967 Mini Deluxe
1973 Clubman Van (the fleet spare)
1978 ex 1275 LS ("Wizard" Eaton Supercharged)
2015 HSV GenF GTS(occasional drive & tow car)
2019 MINI F55 Cooper S

Here we go again....

Really? By the look of it you could fit the carby anywhere between the current location and the blower just by shortening the pipe and moving the washer bottle.