building a new engine for my truck, will be a .030 bored over 302 when put back in, will gt40 heads actually make a significant difference? like to know asap.

 

Over stock? Yes........especially the aluminum.

 

whats better about the alluminum than the cast, i thought they had the same valve specs.

 

I've read alot of the head testing articles in the Mustang magazines over the last several months. Along with the weight savings, they flow better at the ports if I remember correctly, but check out these two sites for more info.

http://www.musclemustangfastfords.com/
http://www.50mustangandsuperfords.com/

Look for the articles on cylinder head testing. They're full of great info.

It also depends greatly on how you plan on using it. It's going in a truck so are you looking for low end torque or is it a street truck? Cam, transmission, gears, it all factors in.

It's not that the iron won't work well, it's just that the aluminum will outperform them.

 

yea, not real worried about the weight, and ive got a 3:55 rear, going with a 302 bored 30 over, flowmaster catback, kandn cold air, maybe a mild towing cam, and whatever i decide to do with the cylinder heads. so its never gonna be a race truck, but just looking for something extra.