GT-40 (P)? Heads
 

I Have been looking at after market heads for my 67 289. Have seen both GT-40 and GT-40P heads. I Have heard that they have different bolt patters for the exhaust side. The reason I ask is, I am getting ready to put Headman Long tube headers on with Flowmaster 3 chambers and am putting these headers on stock heads and would rather not have to buy a second set for the GT-40's or GT-40P heads when I get them next year.
Thanks
AJ

The "P" heads require a different exhaust manifold. You could use them, but you would have to replace your headers.

Take care,
-Chris

Aren't the GT-40X heads far superior to the GT-40 P heads anyway? The GT-40X heads also would use the same headers.

There is an internet article in FORDMUSCLE.com webmagazine called HEAD TO HEAD. It fairly extensively compares a wide variety of Ford small block heads and does include those two I believe. I don't have the address handy, but a search engine should easily find it.

Rev

If you're looking for something cheap, but better than stock, how about the Roush heads? They're about $399 a piece complete from Summit or Jegs.

gt40 P cylinder heads
 

Based largely on reading, I bought gt40P heads for my '67 289 through CJ Pony Parts for only $239.00: complete w/ valves, springs, keepers. However, I discovered through further reading that the heads require special headers because the spark plugs are 90 degree vs. 45 degree for stock. I bought the special headers for a little over $450.00 (I believe they are Thorley or copies thereof): they are full length, beautiful, polished, and fit very close to the block. Again, however, I am converting to T5; these headers occupy the same space as the clutch fork- -they are perfect if you are using a C4 or a toploader- -but simply out of the question for my application.
The P heads are cast iron, (the X heads are aluminum and substantially more expensive) and are supposed to flow better than HiPo heads. I still see ads for the heads from bare to fully loaded for well under $500 for a pair.
(I would cheerfully sell the headers I first purchased at a deep discount for someone who wasn't planning on the T5 conversion.)

Ok, here's my question. Is there anyone who w/out a doubt can tell me which factory, Ford performance, and aftermarket heads use which headers?

One more dumb question. I believe in 84 the motors changed a little(most magazines call these and later 5.0 instead of 302. What are the exact differences in the later and earlier model motors? I've seen some stroker packages that say "designed for 84 and later motors". Is there a difference in the head-to-intake, head-to-header, head-to-fuel pump passages or bolts?

Thanks.

Standard small block Ford exhaust manifolds and headers will work with all small block Ford heads, except for the GT-40P heads. The P heads require a different exhaust manifold. The only thing you need to worry about, unless you are using P heads, is that the headers you select will fit in your vehicle.

The 302/5.0 changed in 1985. Those that came in Mustangs equipped with a 5 speed in 1985, and all in Ford cars from 1986 on, were roller engines, and were equipped with roller cams and lifters. Those built before that had flat tappet, non-roller cams. The new block that was introduced in 1985 was designed for use with roller cams and lifters, but could be fitted with a flat cam and lifters. Older, non-roller engines could only be fitted with a roller set-up with modification.

The truck 302/5.0 used the new roller block starting in 1988, but used flat tappet, non-roller cams and lifters through 1991. In 1992, the truck engine started using roller cams and lifters.

Take care,
-Chris

Thanks, that is exactly what I was looking to find out.