This seems like a good time to get all you can off explorers and such. The cash for clunkers program has my local junk yard full with new cars. They ran something through the engines, but if your gonna get the heads machined anyway they are out there.

 

The PO put explorer heads on my 66 fastback. What is the advantage of those heads. I know they use the small spark plug and the plugs go in at a different angle. Do they have bigger valves and better flow? Do they raise compression?

 

^ you are thinking of P heads. The spark plug isnt smaller, it's longer. The same spark plug is used on the Triton V10. GT40 heads use the same plugs and have the same angle as the stock e7.

 

its a better flowing head smaller combustion chamber
Valve sizes
GT40 = 1.84"/1.54" (intake/exhaust valve size)
GT40P = 1.84"/1.46"
non-GT40/P = 1.78"/1.46"

GT-40P heads are usually 59cc, standard GT-40 heads are 64-66cc. Both can be milled .020-.030 without problems. The compression question, 9.7:1 is too much compression for 89 octane with iron heads. I would stay at 9.0:1-9.5:1 at the most if 89 octane is fuel of choice. Aluminum heads can tolerate more compression.

87-95 Stock E7TE Valve Size Intake - 1.78, Intake Ports Flow @ 124cc
87-95 Stock E7TE Valve Size Exhaust - 1.45

GT-40 Valve Size Intake - 1.84, Intake Ports Flow @ 155cc
GT-40 Valve Size Exhaust - 1.54
65cc Cumbstion Chambers

GT-40P Valve Size Intake - 1.84, Intake Ports Flow @ 185cc
GT-40P Valve Size Exhaust - 1.46
59cc Cumbustion Chambers/61cc Cumbstion Chambers (depends on model)

So in short, they both flow better than stock, however Ps outflow 40s nicely, and they have a smaller cumbstion chambers, along with using different spark plugs and angles.

 

Better flow and more power and torque. I've heard that they provide up to 60 more horses vs stock heads on some 302 applications. But I'm gathering the average is 30 to 40. I'm no expert on them but I've read a little and got some info from alot of helpful people here. I was looking at the e-street edelbrock heads and was told these heads would give me about the same results at a fraction of the cost.

The p heads are from 97 and up and I guess with our cars need special headers to make them work

 

i highly doubt that you would see the gain of a good aftermarket aluminum head. for the price they are a good bolt on. id say 20-30 is a fair expectation since they do add some compression and flow better than some e7's