Ford1158

I'm trying to figure out which swap headers to use that will clear the spark plugs?
My Hooker long tubes would fit the head with a little grinding but they're too wide and hit the strut towers.

Indy

I'm running the BBK long tube 351-into-foxbody headers and had to do no grinding. They even worked out fine when I used to run the DO0E heads which should be very similar in dimension to the GT40P. The DO's even run the sparkplug with the "large" wrench flats on them without clearance issues around the header flanges!

Indy

Indy

Oh yeah... If you are running an Automatic in your fox, the BBK's will not fit around it without massive adjustments to the primary tubes.

Ford1158

Cool - I'm running a manual so clearance there shouldn't be an issue.

Ford1158

Indy - Did you have any clearance issues with your oil pan and sway bar? I'm doing an '80 with a stock Crown Vic pan and it hits a little in front. I don't hear of this problem in the later Foxes.

Indy

Had no issues at all with the sway bar or oil pan on my '79. The only clearance issue I had was with one of the drivers side primary tubes being hit by the steering rag joint. I had to put a slight "dimple" in it with a ballpeen hammer to get it to clear when I hit the throttle hard on a right turn (engine tilt + body roll). However, my buddy had absolutely zero interference issues in his '88 with the swap headers when he ran a T5.

w8less

why would you waste your time installing gt40's after donig a 351 swap? there barely enough for a 302

5.0stanger

Money? 351's come from ford with E7's, got to be better than that.

w8less

yea but most of the time people swap a 351 in for performance reasons. it seems like it would make sense just to hold off on the swap if you cant afford to put a descent head on a motorthat needs it.

and didnt they put the e7's on the truck versions mainly? a small headed motor like that would increase torque but would probably be nothing after 4000rpms

Ford1158

lol, keep telling people that so we can keep buying these things cheap!

I'm doing a budget build and and aluminum heads aren't in the cards. I'll have a decent mill complete for about $1K.

These heads provide a significant bump in compression. They will also hold their own against Performer RPM heads considering the price difference.

This flow data is from:
http://www.stangpro.com/html/article...les/gt40p1.htm

All data is for stock, unported castings:
Intake Flow @ 28" H20
.100" .200" .300" .400" .500"
GT-40P 61 128 169 195 196
GT-40 54 107 157 183 192
E7TE 59 114 144 156 156
'69 351W 52 103 149 174 183
289 50 97 127 156 165
GT-40 (Y303) 64 114 167 199 213
GT-40 (X303) 53 114 170 207 226

Exhaust Flow @ 28" H20

.100" .200" .300" .400" .500"
GT-40P 52 90 123 135 139
GT-40 47 94 119 128 128
E7TE 42 78 105 115 116
'69 351W 48 77 100 113 118
289 37 71 93 104 107
GT-40 (Y303) 52 98 128 137 134
\GT-40 (X303) 50 106 139 153 161

Here's another article:

http://www.mustang50magazine.com/tec..._gt_40p_heads/