Guys this has probably been asked before, but before I sink some money into some good efficient heads I want to see what the GT40's will give me over the stock E7's? Are the GT40's way better than the E7's as far as air flow goes? I can pick up some GT40 heads locally and need to know if they are worth the change to do a head upgrade while I am upgrading the cam on my 92 F-150 302 engine...

 

Another thing are the GT40 heads a direct bolt on to our 92-96 F-Series pickups that come equipped with the 302 and 351w motor?

 

Yes they are a direct swap, and No you shouldnt switch heads, not without switching the intake as well, it would be a waste.Do you have headers and exhaust? If not, even more reason not to switch. Heads come after all other flow issues are worked out with porting/better parts. You wont gain much on that engine with the GT40's.

 

Let's make sure what we're talking about here. There's a GT40 head, and a GT40p. The GT40 is a high performance part. The GT40p is based on the GT40 but it's more for everyday driving. The GT40 is a better flowing head than the E7.

Which head is best for you would be a question of how you intend to drive the vehicle. The GT40 is for highest horsepower, the GT40p would make better torque and get better mileage. The E7's are boat anchors.

 

Well let's just say this on my 92 F-150 I am getting ready to upgrade the base roller cam to a 302HO camshaft and some 1.7 ratio rockers so I thought maybe the GT40 heads would make this even more of a sweeter install. I just want a little performance on the road and more for when I want to go offroad and need the torque to break all 4 tires loose in the mud! I honestly thought I could probably pick up 60-70hp just on these upgrades which includes the 1.7's, 302HO camshaft and the GT40 heads not the GT40P heads...

 

You wont gain 70hp with the HO swap/Gt40's/1.7's. 1.7's would be a waste, you wont get to take advantage of them because of your truck intake, same goes for the GT40's. If your running stock exhaust, thats where you need to focus your energy. then look at your intake. After all that is done, then look into rockers and heads.

 

I have a question, this is a little off topic, but how much are used E7TE heads worth? also how much are used GT40-P heads worth?

 

The 1.7 pedestal roller rockers are never a waste. Not all the gain comes from the increased lift. Actually very little does, you're only opening the valve another .030. The big gain is from the roller trunion, and the friction it reduces. The whole valvetrain cycles easier resulting in a gain of power that's lost with sled or ball fulcrums. Ford found a 15 hp increase just from these on the Cobra 5.0.

 

The emphasis was on the 1.7 part of the roller rocker combo, not the roller itself, I agree, roller rockers are a great benefit, but the whole idea of expecting more from 1.7's on a truck engine is absurd. You wont gain any noticable power from the extra .030 lift.

 

The way I look at it, since 1.7's cost the same as 1.6's, the waste is in the 1.6's. You might benefit from the increased lift, that never hurts if it's there. If it's not then you've still gained from the friction reduction.

 

If it makes you happy, right on!

 

With a 1.72 roller rocker you get extra lift on every cam revolution.. at all rpms. Open the valves higher, more air/fuel gets in, more power is produced. These will produce a boost in output across the rpm range just like a cam with more lift would. Everything you do to improve the breathing capacity of a motor results in power increases. It's not just about the peak numbers, it's the area under the curve.

 

But if your not increasing the flow of the bottleneck (intake, exhaust, etc.) you wont gain anything with .030 more lift (and the corresponding duration @.050), usually 1.7's and 1.72's are more expensive than 1.6's. Not worth the extra cost and valvetrain stress caused by the larger ratio.

 

I see your logic.. but it just doesn't hold water. The early flat tappet truck motors has sad little cams with less than 0.400" lift, and were rated at 185hp peak. The F4TE motors got a cam with 0.430-0.440" lift and were rated at 210hp peak. These trucks were otherwise identical, same intake, same 2.25" single exhaust system, but I can assure you there is no mistaking which verson is which when you drive them. The later motor makes more power everywhere.

 

Yes, but the F4TE is also a roller cam which frees up more power than your .030-.040 lift did. The 94-95 5.0's were rated at 205 (195 for the auto) which are revised estimates from ford. I think the change in power numbers came directly from the change in the way the power was measured. The 351 in 94 didnt change 1 bit from 93, and it was rated at 10 HP/25 ft.lbs more than in 93. same with the 460 as far as an increase in power, yet with no change in the engine. I would find it hard to believe that the F4TE cam change was worth 25hp/5ft.lbs more than the flat tappet truck cam. I bet if you took identical truck engines, side by side, one with an F4 and one with the flat tappet, you might see a 10hp difference tops on the dyno, and most of that would be duration and the fact that it has a roller cam. .030-.040 more lift on stock ford E7's will not make a difference.