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?
4 replies to this topic
#1
Posted 31 December 2017 - 09:33 PM
#2
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.
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
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.
Phil.
#4
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
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
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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