I own a 1989 Bronco with a 302. Has anyone out there swapped out their original cylinder heads with the GT40's? Would these heads matched with a new performance camshaft and springs make a significant difference in performance? I have the opportunity to pick up a set of these heads off a 93 Mustang really cheap from a buddy of mine. Just wondering if it's worth it? I'm interested in hearing everyone's opinion.

Bronco894x4

 

I haven't tried it myself, but I'd like too. I've been told that Ford has pretty restrictive heads, and that changing them out will give you a pretty good performance gain.

 

I just bought a brand new pair of 'em! I know they fit, but I don't know how it's gonna perform yet. I should have everything together and running in a week or two, and I'll have it Dyno'ed about 500 miles after that.
The thing that sold me on the heads was the cost. It was actually cheaper to buy a short block and GT40 heads, than for a bone stock long block. Since I saved a few bucks that way, I just couldn't resist adding an e303 cam, headers, header back exhaust to the grocery list. Hmmm, maybee I didn't save any $ after all...

I have a question for you. Why is your buddy selling the heads?

 

He doesn't feel like he's getting the performance he wants out of them and can do better. I think he's changing the intake manifold as well. Hmmm. Will that fit? I think he's just DUMB!

Bronco894x4

 

Check the ports on the stock intake,if they are smaller than the gt-40's than you will not see the full benefit of the larger heads.If you use the gt-40 upper and lower you will have to fab a bracket on top for the accelerator and tv cable if it's automatic.

Billy

 

Cajunbronco, sounds like you have some experience here! I want to use the GT40 intake, but it, like most others are for 'stangs, and feed from the side. What changes are necessary to switch to the Mustang type intake, and would this mean I could install a Mustang supercharger kit?

 

An other thing to consider is the fact that you will be running Speed Density VS. Mass airflow. The larger heads may upset you stock ignition/fuel managment system. You might want to think about also buying the ford mass air conversion kit. About $600. Also, check the exhaust ports. The stock heads have rectangle shaped exhaust port, i think that GT-40 heads have square ports. It might be hard to find headers that will fit (must clear the front engine cross member). Good luck, let us know what you come up with.

 

You can make the swap work,there was a guy on another Bronco Board who was running gt-40 heads and intake.He had to fab up a bracket for the throttle linkage and the tranny cable.Mustang shorty headers will work.

Billy

 

That guy might have been me. I sold my Bronco a few weeks ago, but I had the 302 with GT40 heads/intakes/75 mm throttle body. I set it up like the Gen I Lightning. I also had numerous other mods, but here's the take on what you are looking at doing:
Cast iron GT-40 heads are not worth the money. The stock truck heads are just as good. Port and valve sizes are the same. The upper and lower intakes are better than stock. You can buy a high flow throttle body made for the truck so that you do not have to fab up a bracket like I did.
You need to figure out what you are looking to get out of your truck before you start installing parts. Decide if you want low end torque, or a cool sounding idle (hence the E303 cam on another post, lose the low end, but get a slight lope at idle) If you go bigger cam, you need to can the speed density system, and go for the mass air conversion.
Power costs money. Power properly matched costs even more money.