I know that the options are endless, but does anyone have any advise on what they have found to work on these 302's as a fairly straight forward option for better performance heads. Right now they are stock for a 68, thought about bumping up to the 351 Windsor but after a little research there are about 10 million options out there! Currently my headers fit the angled spark plugs. Any help?
1968 Mustang 302 Head options
- Thread starter mustang8
- Start date
Are you wanting to use an OEM Ford head? If you have an original four barrel '68 302, those heads were supposed to be better than the two barrel heads. '69 and '70 351W heads used to be the hot setup, but they only have larger intake valves and ports. The anemic exhaust ports are the same size as 260, 289 and 302.
The GT40 heads from Explorers have better ports with same size valves as the first 351W heads and flow better than regular 302 heads. You just need pushrods that go with the GT40 valves and rockers (measure to verify fit). The GT40p heads from the last 302 Explorers flow the best and have much better shaped combustion chambers, BUT the spark plugs are relocated and take special headers.
The plain GT40's are probably the easiest to install, but may have larger chambers than your 302 heads, thus less compression. At least make sure you have flat top pistons, no dish!
Do an internet search on small block heads. There are lots of charts showing compression ratios, valve sizes and airflow of the various heads.
I drag race a '67 Cougar with a 289. I started out with ported '65 289 heads with 1.90" and 1.60" valves. Best times were 12.90's, usually low 13's. Then I went to GT40p's, stock size valves and ported exhaust. Was a bear to get the headers to clear the plugs. It would run in the 12.8's. Now I have Holley aluminum heads and it runs 12.60's-12.70's.
The GT40 heads from Explorers have better ports with same size valves as the first 351W heads and flow better than regular 302 heads. You just need pushrods that go with the GT40 valves and rockers (measure to verify fit). The GT40p heads from the last 302 Explorers flow the best and have much better shaped combustion chambers, BUT the spark plugs are relocated and take special headers.
The plain GT40's are probably the easiest to install, but may have larger chambers than your 302 heads, thus less compression. At least make sure you have flat top pistons, no dish!
Do an internet search on small block heads. There are lots of charts showing compression ratios, valve sizes and airflow of the various heads.
I drag race a '67 Cougar with a 289. I started out with ported '65 289 heads with 1.90" and 1.60" valves. Best times were 12.90's, usually low 13's. Then I went to GT40p's, stock size valves and ported exhaust. Was a bear to get the headers to clear the plugs. It would run in the 12.8's. Now I have Holley aluminum heads and it runs 12.60's-12.70's.
JeffB2
Well-known member
You might want to read all of this: http://www.fiveohinfo.com/performance/gt40-gt40p.html By the time you upgrade the later Ford heads you could come out better $$wise by going this route: http://www.hotrod.com/how-to/engine/ccrp-1302-six-budget-ford-heads-that-work/ The Flo-Teks would only cost you a tad more.
Wow thanks guys for the input that is exactly what I was looking for! Good articles to check out, definitely some power to be found with the gt40 heads, I wonder what size studs the rocker arms have on them, I have a set or new comp cam rollers for the 3/8" studs that I would like to install if im going to mess with them.
The GT40's and p's use the stamped steel rocker arms, bolted down with 5/16" bolts; non-adjustable except by shims. Your roller rockers will likely need guide plates and hardened pushrods so you need to mill down the rocker stands the thickness of the guide plates and drill and retap for 3/8" studs. Easy and cheap if you have access to a mill. Otherwise, it's an additional cost.
Be wary of cheap aluminum heads! If they're complete, the valves, springs, etc. are the cheapest they could find. Sometimes the seats and guides need to be reworked. Sometimes the rocker stud locations are off and the valve train geometry is messed up enough to take out the guides.
