Which heads are better gt40 or gt40p

On these heads, the installed height of the intake valvespring is around 1. Because of this discrepancy, the exhaust valve's valve-lock groove must be shorter to allow sufficient room above the retainer for the guided rockers.

This reduces the actual distance between the bottom of the retainer and the top of the valve guide and seal, so this combination can't accommodate any kind of performance cam with more than 0. The production Ford GT40P iron head offers decent flow as a stocker, but it needs a few modifications in order to accommodate more valve lift. The easiest way to identify the GT40P head is these four vertical casting marks on the outside of the head. To verify, GT40P is also cast into the head usually!

The keeper groove in the stock exhaust valve left is lower than with non-rotator-style valves because GT40P heads use shorter springs and a thicker retainer. We decided to use new valves from Manley right with keeper grooves in the same location as the intake valves, making assembly simpler and easier. Other valvespring kits compensate with different retainers or keepers to communize the installed heights.

A valvespring's installed height is the distance between the spring seat and the bottom side of the spring retainer. In order to use the Lunati dual springs, this required machining the lower guide boss arrow to reduce its 0. Slover's Porting Service did this machine work at the same time that the heads were ported and machined for screw-in studs.

These heads use a net lash valve system instead of a traditional stud-mounted, adjustable rocker. Net lash rocker stands use a bolt to position the rocker arms to the head, which is tightened to a preset position.

This system is easier and quicker to install on the production line, but doesn't allow for lifter preload adjustment. Plus, the stock inch retaining bolt is weak. To make these heads work with a performance cam, Slover's Porting Service milled off the original net lash bolt pads to install inch screw-in studs with a inch bolt size in the head and changed the exhaust valve to ones with a taller keeper groove so the installed height would be consistent with the intake.

This means the head would be able to use the same valvesprings, retainers, and keepers for all 16 valves. This conversion also required machining the guides to reduce their overall diameter to fit the 1. Lunati dual springs. Of course, there are alternatives to this approach that can be accomplished without removing or machining the heads. For successful registration, you must use an email address assigned to you by your internet service provider. Poll Options Which Head is better?

Stock GT40 iron. Stock GT40p iron. View Poll Results. Before answering the poll, consider: You have a choice between a set of heads of a '96 explorer GT40 or a set of heads off a '98 explorer GT40p. The headers will not be a problem , because you want to upgrade your existing stock headers and you have not already bought a set that fits the orginal ET7E's.

Both sets are iron so aluminum is not a factor. You should definately go for the GT40 P heads. They actually flow better than the GT40 iron heads. I know, it sounds weird, but there have been many flowbench tests done on these heads. The revised spark plug location makes the fuel burn much better and also creates a bit of a swirl in the chamber for fuel mixing.

The GT40 iron heads are much more expensive. If you're interested in a set of the P heads, email me at mblack ou. Coming soon: 6 or 8 point cage, Fuel Cell, Weld Draglites. Find More Posts by QuantumMotorsports. How well would they work on a ? I think the GT40 Iron heads are better for me. GT40 heads can use normal headers, the P's have to have special headers GT40 heads work with the factory smog lines, and the P's do not accept factory emissions.

GT40 heads have larger Exhaust valves from factory. I will say, if your going to just leave them stock, dont bother, but with porting they'll be good, i would rathe rhave ported e7's with some good springs, then some unported gt irons Re: gt40 vs gt40p.

This appears to be an ancient topic, but since the recent comment was made, I feel a need to chime in on this debate once again. Out of the box the GTP's flow better, burn fuel more efficiently, and have a smaller combustion chamber higher compression , than the GT Irons. The GT Irons you'll usually find have a better valvetrain capable of taking cams with lifts somewhat higher than.

There should be no debate still out there on which head is superior. The GTP is by far the better head, no ifs, ands or buts.

As to the aluminum aftermarket heads vs. Bigger is not always better, and the GTP heads can make excellent power while not killing your performance below rpm on a small block , unlike any aluminum head that's going to be really suited for a or stroker.

Building an engine is not like building a computer where the parts work independently. If you put a set of big, high performance aftermarket aluminum heads onto a without changing the intake and the cam, you're just going to get an unresponsive, torqueless gas guzzler because the port velocity is going to be terrible as the intake won't be able to flow to match.

Okay, so what if you cam the little to the moon. You now have an engine that should have good port velocity Oh, and your fuel economy will suck, and you'll have to keep the engine above 4,rpm to notice the extra performance. The smaller combustion chamber can net a bit more compression, but only marginally. Conclusion: "one is not downright better than the other. If you're stuck deciding between the two, go with whatever is available and at a better price.

We will consider intakes from a Cobra or Explorer the same. ChampCar Tech Desk The tech desk is used to ask technical questions and is not to be used as a post race tech line or to phish for how others built their cars. You can download the BCCR here: https:champcar.