MonsterBilly

I have a set of 289 h a ads from my mustang. They have been ported and have screw in studs with guide plates and a recent valve job with some good solid springs.

I picked up a 75 bronco with a 302 which is bone stock. It has a 2bl carb. I also have an extra 60pcfm edelbrock carb and a brand new intake. So I was thinking, if I'm gonna put the carb and I take in, why not put on the 289 heads that have been worked over?

Please gimme your thoughts

groho

does your 75 heads have a air injection ports? that was pretty standard back the early 70's.

barnett468

The 289 heads should have smaller combustion chambers of 54 cc . You will need premium gas and will need to curve the distributor for optimum timing.

If the 302 has flat top pistons, you should check the deck height of the pistons and use a thinner head gasket if necessary to get the quench/squish clearance between .043" and .034".

MonsterBilly

I'm not sure if they have air ports. It did have a smog pump which has since been removed if that is any in inclination

I have not taken the intake and heads off of the 75 yet. It runs fine I just have the stuff laying around so I thought what the hell. I also have a new set of roller rockers as well so I may as well get a cam.

fastbackford351

If you have a set of bone stock 75 302 heads vs. some worked over 289 heads, I'd find it hard to believe that the 289 heads wouldn't be a better setup all the way around. By 75 Ford heads were so pitifully choked back, especially on the exhaust ports that they were a bad joke for making power.

I'm usually a guy who subscribes to the "if it ain't broke don't fix it" mantra but in this case, I think I'd make that swap.

rmodel65

sell all those heads and get some heads from a 96-97.5 explorer...then youll have gt40 heads that outflow all stock 289/302/351w heads even the c9 and d0 351w heads

crazyJak

Hello, new member logging on for first time. I remember putting 351W heads on a 302, after having them milled down to restore the comp ratio. The 351 had bigger valves. You had to use a certain head gasket to allow water flow. Anyone know if this would work on 289s?

rmodel65

yes..but gt40 heads from a 96-97.5 ford explorer outflow the 351w heads from 1969-1970 and already have hardened valve seats. and you can find them all day long for 100$ or less at the local pull a part place..

69mach1377

^Don't those require special exhaust manifolds or headers?

barnett468

not the gt40's . the gt40p heads sometimes require short spark plugs and ceramic boots, but most headers will fit them.