Mustang guys love port/polished GT40s. For the price they are a good head, but lots of times they just go with a Trick Flow topend. AFR heads rock 165cc, but pricey. Port/polish GT40s would really open up your truck, I bet.
What are you power goals? If you want anything resembling low rpm power from the 302 use the stock E7 heads with an exhaust port job only. Every other option will give you more peak HP at 5000rpm and above, but will cost you low rpm TQ. The fully ported GT40's will make the most HP.
If these are for the '89 in your signature you need a cam upgrade from stock to fully utilize either of these options... including untouched stock heads.
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Paul O
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1990 F150 4x4 XLT Extended Cab (Currently undergoing a heart transplant)
1990 Ranger 2wd, 2.3 Briggs & Stratten, 5-speed, 3.08
check out thumperoforangepark.com. i had him port and polish my e7s. i also installed bigger valves and comp springs. my 302 runs very healthy now! i did a mass air swap also to take advantage of the improved air flow.
i agree with Conanski, i put the thumper heads on my truck with a mild roller cam and the stock speed density computer system and i lost mpgs and performance was hardly felt. but when i switched to mass air computer system i gained alot of power and mpgs! but that was a expensive route.
What are you power goals? If you want anything resembling low rpm power from the 302 use the stock E7 heads with an exhaust port job only.
Low rpm power is EXACTLY what I am looking for. Conanski, from talking with me in the past, you know that I have the E5 heads, which I am told is very similar to the E7 heads. In conjunction with the Comp cam you recommended, is the "exhaust port job" all I need to do also?
What does an "exhaust port job" mean exactly? And why do I need to do that? Sorry, I am still learning and I don't really understand everything about mecahnics, YET. Thanks for all of your help, Conanski.
All of that info is kind of a waste of brain cells if you want low RPM grunt. That is not to say poorly designed heads couldn't benefit from a clean-up on the exhaust side, but major gains are usually over 4000 -5000 rpm. The premise is to reshape the short turn so that the valve flows the exhaust toward the exit more efficiently and clean up the exit of the exhaust side of the heads. Gasket matching so that your exits are the same size as a basic exhaust gasket will help out. As far as low RPM is concerned, a set of headers and good flowing exhaust with a RV/towing type cam will do the most. Once you want higher RPM power, you need to change all that other junk.
In fact, as cast, many Ford heads could benefit from a good clean up. I have home ported both my small block and big block heads with good results. I don't claim to be an expert by any stretch of the imagination, but I have tinkered with older Fords and found much of the above to be true.
More horsepower and better gas mileage kind of don't go together...
Brian .. I'd have to say I agree with everything you posted.. go info. The Ford heads are small compared to most of the competition, this is bad if you want big HP, but good if you want better than average power right from idle. The exhaust side of the small block heads are particularly restrictive and anything you can do to improve exit airflow will help make more power without impacting intake airflow. Fully porting the exhaust ports involves smoothing the bowl area behind the valve, blending it into the roof of the port and around the valve guide, and then opening the port exit in a smooth continuous manner so it transitions to the exhaust plumbing smoothly. Air under pressure will follow the outside radius of a turn, so the primary focus of exhaust port work should be on the walls and roof of the port. This work is absolutely necessary to to realize gains from headers and upgraded cams, but every small thing you do will add up to significant gains when they are all combined.
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Paul O
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1990 F150 4x4 XLT Extended Cab (Currently undergoing a heart transplant)
1990 Ranger 2wd, 2.3 Briggs & Stratten, 5-speed, 3.08
Great info here...I was alos mentioned by someone that polishing my hurt your power gains and a little roughness in the passages would help it out a bit better......slow the air down just a bit...
Great info here...I was alos mentioned by someone that polishing my hurt your power gains and a little roughness in the passages would help it out a bit better......slow the air down just a bit...
JR
On the intake ports a rough finish does flow better than a glassy smooth finish, the rough surface traps a film of air near it and decouples the air column so it will flow faster.
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Paul O
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1990 F150 4x4 XLT Extended Cab (Currently undergoing a heart transplant)
1990 Ranger 2wd, 2.3 Briggs & Stratten, 5-speed, 3.08
Is another function of somewhat rough surfaces in the intake and intake side of the heads fuel atomization? Or has that already happened as much as it's going to by the time it hits the heads?
Nah Brian that'sa good theory as a matter of fact......if it'ssmoother chances are the air will just be more turbulent and force raw fuel into the cylinders where as a rough surface would hinder that effect.....that's how i see it anyways....
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What's best: GT40; port & polished GT40 ; port & polished stock
