Hello everyone.

I have a 67 Bronco that I've put a 5.8 EFI out of a 1990 f250 into. I used the stock heads with a small amount of porting done to them. I now have a set of GT40 heads off of a 1997 explorer. My question is.....is it worth my time to put these on my engine? If so what gains will I see?

Thanks
Kris

 

There's no way to know what impact your porting had, but the GT40 heads have much better port shapes and untouched are good for a 20% increase in airflow over E7's.. so yes it's worth it IMO.

 

Thanks! My other question...are the intake and exhaust ports the same shape as my stock heads as far as using my stock intake manifold and my headers?

Thanks
Kris

 

Yes same shape and location though the intake ports on the GT40 heads may be a little larger than the E7's. I find the last inch or so of the lower intake ports often narrow just before the gasket surface so don't be afraid to open this area up a little, just be sure to leave enough material to seal the gasket.

 

wouldnt those heads be gt40p heads and not the regular gt40's?

 

These are from a 97 Explorer so I believe from what I've been reading that they are still the regular GT40's. I'm hoping anyway I will be tearing them off in a few days and will know for sure.

 

'97 was the switchover year so they could be either version.

 

If they end up being the "P" heads I will probably end up selling them because I don't want to change my exhaust setup. Is there much of a market for them?

 

If they end up being the GT40P's, don't immediately write them off. They are a better head and the header/manifold fitment issues are a bit overblown. I've found several sets that fit them just fine or with a minor ding for plug clearance. I'd at least see if your headers/manifolds will fit them and allow for plug clearance before I unloaded them. There is a market for them. They can bring around $250-$300 for a good used set.