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First of all, Can I take the GT40-P heads, and have them drilled for 2.02, 1.60 Valves? Would it be worth it? Also, who sells the headers for the conversion of GT40-P heads in an early mustang? Thanks for your time.
 

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For the GT40 heads...it is not a good idea to install the 2.02 intake valves only because the combustion chamber is rather small and they'd have to cut into the combustion chamber......to "unshroud the valve..." otherwise...a shrouded valve WILL NOT flow and swirl
the airflow right causing the port velocity to slow down thus losing power and torque etc....

Ask the machine shop what the biggest "unshrouded" intake and exhaust valve size can be used. it will probably be close to 1.94/ 1.60

aim for the 1.94

the risk of messing up flow velocity and swirl is too high

sometimes "the bigger the valve" is not always the best policy or
method.....look at the 69 Boss302.....they changed the valve size in 70 because it was shrouded......then port plates came out because the ports were too large for any practical street use.....

This is why everyone is switching to the Aussie style heads.....
smaller valves and ports....that yield you a higher port velocity.
when valve bowl work is done properly will fill the cylinder much better than the boss or 4v heads will....

look up

www.replikamaschinen.com for some good points on airflow of internal combustion engine.

have a great day!!
Roberto
 

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If you want good flowing heads get a set of early Ws port them put oversized valves and you have a performer rpm flowing head...
 

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If you already have the heads, CAPonyboy's advice sounds pretty sound. If you don't have them already call the guys at Central Coast Mustang and they can set you up with the right valve sizes for your cam, etc. I have a pair of GT-40P's from Central Coast Mustang on my 302 and I'm very happy with them. They provided the tri Y's as well and the combination makes really great power. The real advantage of the GT-40's over the stock heads or even 351 heads is the more balanced volumes of the exhaust and intake runners. These heads breathe better than the old stock type (like the Clevelands vs. the Windsors) and don't need huge valves. They just achieve better flow blance and are more efficient.
 

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I have flow bench results between ported W heads and gt40p heads... all i have to say is the W heads kicked A$$!

Mathew
 
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were the 40-p's ported also. i would sure like to see the numbers. because the flow bench numbers i have say just the oppisite.....Allen
 
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