What is needed to make GT40 heads work on a 351W? I've read just about every post on every forum and cannot find a definitive answer on what parts or work is needed to make it work and furthermore if the stock headers will still fit.
I currently am about to pull my engine for rebuild (1988 F150, 4x4 BW1356, C6 Trans, 351W EFI). I still need to run all smog components because of local emission laws and cant really get around that.

Any assistance would be appreciated.

Thanks

 

I've had a set on my 5.8 for a few years now.

Original GT40 heads with the 3 bars on the end & not GT40Ps will accept stock manifolds & shorty headers.

You may need (probably) to have the head bolt holes drilled out to fit 1/2 head bolt size of the 5.8

Explorers that have GT40s harvested off of them (5.0), usually have holes for 7/16, but I've seen plenty of both.

 

I took the 3 bar GT40 heads off my 302 and had the head bolt holes drilled out for the 351W.

 

Depending on what the vehicle they were originally installed in 3 bar GT40 heads may or may not be machined to accept the AIR crossover tube found on 302/351 trucks. As mentioned above, the mounting holes may need to be enlarged for use on a 351.

Otherwise 3 bar GT40 heads will work just fine, assuming everything else is stock.

4 bar GT40p heads will not.

 

Thank you all for the information you have provided I really appreciate all the info you guys have. It's simple as slapping on 3 bar GT40 non p heads after drilling the holes out to 1/2? Regarding the AIR crossover is there a way to check if the vehicle has it before getting too deep into removal at a junkyard? I know it's emissions related and I'm in the strictest state for that (CA). How do you figure out which vehicles are going to have that? Explorers/Mountaineers ect.

 

Yep. As the other guys said the 3-bar GT40 heads (not 4-bar GT40P heads) are an easy bolt on swap.
I was lucky enough to find a set from a 351 so I didn't even have to have the bolt holes drilled.
As R&RFord mentioned above, mine didn't have the provision for the AIR Pump tubes, but that wasn't a concern for me since I wasn't planning to run the AIR Pump anyway.

 

I believe, this is why he's asking, not if they just fit the motor, but what he needs to do to make sure he gets " emissions legal". Dont think it's going to be easy to find the needle in hay stack, where your at.

 

The rear air line will bolt on GT40 heads just fine so it's not hard to make it look correct, and once the motor reaches operating temp.. which could be as quick as 30sec after startup the smog system diverts air downstream to the cats or bypasses the whole system, so not having a functional upstream air line won't make any difference to the tailpipe emissions.

 

That's definitely also a big factor here. Did they make a version that has the air bypass or does that not exist?

 

Conanski answered, just finding all the parts now, start with rock auto, and see what you can get from them. and make check list, unless you have everything still on yours, then use them.

 

What parts are you referring to? Also I read on a forum somewhere that I have to use a different non 351 gasket for these heads is that true?

 

So the GT40 heads do have the AIR tube or they don't I'm not sure I understand. If they do not how does that work with routing the smog stuff. I still need to pass a particulate test where I live and I'm not sure how much difference that AIR tube makes on that. Unless I misunderstood upstream vs downstream.

 

Not all 3 bar GT40 heads are set up to use the AIR cross over tube, depending on the application they were originally set up for. Heads from first gen lightnings will be setup for the crossover tube, most others probably are not. The heads I am currently running were not setup for the crossover tube. The best way to tell is a visual inspection of the head...

As far as emission testing goes it is a crap shoot. Many states have visual inspections and tailpipe emission tests. Lots of things could potentially fail a rigorous visual test, like not having a AIR crossover tube, but I don't think it is something that would jump out to many people unless they saw something else to cause them to start looking for problems. Tailpipe emissions will usually be fine so long as the engine is properly tuned up and running well and the catalytic converter is functioning. The AIR system helps the stock converter to work under various conditions, like at cold start up.

If you are worried about it make sure you find a set of 3 bar GT40 heads that will accept the crossover tube or use a set of the stock E7TE heads.

Assuming you are looking to improve output of your 351, you will do much better to get a better cam and keep the stock heads than to keep the stock cam and go with the GT40 heads, and have no emissions inspection concerns.

 

Got it, thank you for the information. Concerning a cam kit is there a go to Flat Tappet that guys are choosing for this application or is it a per case scenario. The basis is that the engine is going to be out and rebuilt so while I'm there I'd like to add a little extra power since I'm already tearing the whole thing down.

 

Some are drilled for air some are not.
The crossover tube will bolt on any SBF head.. doesn't matter if they are drilled or not. These heads are universal meaning they can be used on either side of the motor, so there is a threaded mounting hole on both ends. On the front of the motor that hole is used to mount accessory brackets, on the back it's used to mount the air tube.
It won't make any difference. The air is only injected at the head(upstream) for a short period at cold start, then it switches to downstream(at the cat) as soon as the EFI system goes into closed loop which is pretty quick usually. So if the heads aren't drilled for air the system won't pass air at cold start but that won't matter for a smog test because the vehicle has to be driven there so the motor will be at operating temperature in closed loop by that time.