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John Cooper Performance Conversion Kit ?


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#1 not for sale sorry

not for sale sorry

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Posted 16 June 2011 - 06:01 PM

Hi i havent bein on hear for a while i sold my mini a few years ago to keep funding my business, i have now bought a mini checkmate with my girlfriend and it has a john copper performance kit fitted, now apart from the twin su's under the bonet what else is done to the engine etc? we are collecting the mini sataday night and i need to do the head gasket on it witch i will start on sunday and see if they have done head work etc to it, any help would be great many thanks :D

#2 minisam92

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Posted 16 June 2011 - 06:04 PM

if its cooper s conversion i think they bolted a stage 2 janspeed head on lcb rc40 exhaust system and high lift rockers not sure about anything else hope this helps m8 :D

#3 not for sale sorry

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Posted 16 June 2011 - 06:11 PM

i no it has a long centre branch and rc40 fitted so that sound about righ mate cheers

#4 minisam92

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Posted 16 June 2011 - 06:13 PM

i think standard the janspeed heads were blue aswell if that helps

#5 Bungle

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Posted 16 June 2011 - 06:25 PM

you won't have the hight lift rockers on a 998

#6 not for sale sorry

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Posted 16 June 2011 - 06:59 PM

you won't have the hight lift rockers on a 998

How do u know it's a 998? Your right though it is lol

#7 RossKnight

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Posted 16 June 2011 - 07:06 PM

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#8 Bungle

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Posted 16 June 2011 - 07:10 PM

you won't have the hight lift rockers on a 998

How do u know it's a 998? Your right though it is lol



because you said it's a mini checkmate and i'm sad and know they came with a 998cc engine

Edited by Bungle, 16 June 2011 - 07:10 PM.


#9 not for sale sorry

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Posted 16 June 2011 - 07:16 PM

Just found this Top
by taffy1967 ยป Thu 7th Jun 2007, 01:42pm
I believe the last (British at least) twin carburettor Mini produced was the final Mini Cooper S back in July 1971.

Although BL's Special Tuning department did offer performance upgrades for the Mini 1275GT which I believe included twin carbs?

Then In the mid/late 1980's (prior to the launch of the Rover Mini Cooper), John Cooper was supplying twin carb performance kits to Japanese Mini enthusiasts and new management at Rover saw these special John Cooper Conversion kits become available as optional extras by most Rover dealers. The 1990 versions of the Mini Flame Red, Racing Green and Check Mate LE's were launched with that special kit in mind and it featured in their brochure. Plus those models came equipped with the classic 3.44 final drive too.

The early Rover Mini Cooper of 1990/91 (RSP LE & Mainstream), both used the single HIF44 carburettor, but there was the option to upgrade the cars to Cooper S spec with another Cooper Conversion kit that also included twin carbs. Or there was the 1400S conversion that really made them fly.

Here's a link to the John Cooper Conversion kit from the Flame Red, Racing Green, Check Mate LE brochure: -

http://www.roblightb...s...g 10 11.jpg

#10 Mini-Mad-Craig

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Posted 16 June 2011 - 08:34 PM

You can always rely on Darryl :D

#11 minispaniard

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Posted 16 June 2011 - 08:58 PM

get in touch with the "classic mini john cooper conversions" guys on facebook

Click here

I hope the link works, if not I guess you'll find it by typing it on search tool :D

#12 harrythehat

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Posted 01 May 2018 - 06:42 AM

have what I believe is an early JC conversion 998 by the engine code and would like to try and find out what was done back then, without stripping it down if that is possible.

 

from a visual look

head is stamped john cooper unleaded and a string of different numbers, could they be rebore details?

 

exhaust and inlet ports have been taken out, (to the max by the look of it) polished up lovely.

 

rockers these have all been ground down, (lightened and balanced?)

 

engine was rebuilt by last owner an ex leyland engineer of the old school past away now unfortunately

 

did a dam good job by the way it runs.

 

As a comparison have a 99 paul smith MPI it Alice will take that without a problem on acceleration and prob top end

 

Any clues would be gratefully accepted

thank you



#13 minidizzy

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Posted 01 May 2018 - 08:52 AM

The 998 John Cooper Conversion did not involve any work to the block. The kit consisted of:

an exchange head developed with Janspeed with polished inlet and exhaust ports and specially shaped and polished combustion chambers - compression ratio was 9.8:1

an LCB exhaust manifold with twin silencer

twin SU 1 1/4" carburettors and manifold with K&N pancake filters

MG Metro rocker cover

 

The rockers were not changed or worked on nor was the final drive.

 

I am not sure what all the coding stamped on the head means. It would include "Cooper unleaded" and numbers like 55, 5.5, 0.018 and the date.



#14 r3k1355

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Posted 02 May 2018 - 01:49 PM

Just check the relevant parts are there, if not you might be able to buy them second-hand anyway.

 

have what I believe is an early JC conversion 998 by the engine code 

 

The kit was aftermarket, it could have been put on at anytime (unless you've got paperwork showing when it was installed)

You've also no idea if previous owners swapped and changed bits around over the cars lifetime.



#15 harrythehat

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Posted 11 May 2018 - 05:06 PM

Would you believe it the original certificates from John Cooper and invoice has turned up giving all the data needed

pleased as punch

up for sake on fleabay now






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