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Porting A Cooper S Head

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#1 Mini 1100 special

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Posted 31 December 2017 - 09:33 PM

how much can you port a standard 12g940 cooper s 1275 head I want the biggest valves possible the valves are very close together at the moment don't have photos can anyone help? would it be better too port cooper s head than normal 1275 head? 



#2 nicklouse

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Posted 31 December 2017 - 11:00 PM

The castings are the "same" and can be ported to the same specs (early S heads excepted) but a standard S head with correct markings etc would be worth more if left untouched.

Valve sizes depend on what the cam/use will be and if you are looking at unleaded seats or not.

Edited by nicklouse, 31 December 2017 - 11:01 PM.


#3 Turbo Phil

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Posted 01 January 2018 - 02:34 AM

There's no advantage to porting the S head, any 940 can be ported just the same. Personally i'd start with a standard 33/29mm valved head, that way you've got as much material as possible to work with to allow the throats especially to be shaped effectively.

Phil.

#4 mini13

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Posted 01 January 2018 - 10:09 AM

The best way to port a Head especially the mini ones, is to send it to someone like Phil^^^ with some cash.

#5 ACDodd

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Posted 01 January 2018 - 02:50 PM

Listen to Phils advice.

Fitting the biggest valves posibble in a head destined for road use, is recipe for the shortest service life from the head. Limit valve sizes to 35.7mm intake and 29.4mm exhausts.

Ac





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