Go Back   Ford Mustang Forums > Mustang > Classic Mustang > Classic Tech

Welcome to our Mustang forums where Mustangers come together to hang out, discuss and enjoy their favorite Mustang hobby with fellow Mustang enthusiasts. We invite everyone to read, post, and enjoy our Mustang forum as well as the many other sections of our site.

You are currently viewing our forums as a guest. By joining our community you gain access to post topics, communicate with members, upload your photos and access many other special features. Registration is fast, simple and free so why wait, join our Mustang community today! If you have any problems with registration or your account login, please contact support.

Classic Mustangs Tech Forum

Technical discussions specific to 1964-1967, 1968-1970, and 1971-1973 Classic Mustang. Discuss all tech related to in-line six cylinder and V8 powered Vintage Mustangs here.

Classic Forums | Classic Talk | Classic Tech | Classic Pictures | Introductions | Mustang Tech | Mustang Lounge 


Reply   Post New Thread
Unread 08-24-2011   #1 (permalink)
Cannon.chris101 is offline Rookie


Joined: Aug 2011
Posts: 2 Threads: 1
 Cannon.chris101's Country Flag
Cleveland   Tennessee
Cannon.chris101 is on a distinguished road
Default Which heads are better 1970 Mustang 302 heads or gt40

I have a 1970 Coupe with a 302.It was a daily driver until some valves started pinging. So i pulled the original motor out and i had a '76 302 that fairy new so i stuck it in. I also added a performer intake, 500 cfm carb, and headers. But my car seems slower now than before. so i would like to do a head swap because i understand that '76 heads are extremely weak ( goverment emisions) Would i be better off to get my original '70 heads redone, with a hotdip, pressure check, ect ect, or would a good set of gt40 or gt40p heads be better (i understand my headers may not work with gt40p)????




1970 coupe 302 C4
2007 V-6 5-speed, shaker 500, premium wheels ECT ECT
Cannon.chris101 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Unread 08-25-2011   #2 (permalink)
Lizer is offline SHELBY GT 350 Member

Classic Member


Joined: Dec 2009
Posts: 5,701 Threads: 95
 Lizer's Country Flag
Kalamazoo   Michigan
Lizer is on a distinguished road
Default

gt40 heads any day over those. The gt40p's flow a little better but you won't get the header issues with the normal gt40's.
Lizer is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-06-2011   #3 (permalink)
Cannon.chris101 is offline Rookie


Joined: Aug 2011
Posts: 2 Threads: 1
 Cannon.chris101's Country Flag
Cleveland   Tennessee
Cannon.chris101 is on a distinguished road
Default

all right thanks a bunch. Im new at the car game and im self taught so any imput is great. thanks
Cannon.chris101 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-07-2011   #4 (permalink)
Dave is offline MACH I Member

S197 Member


Joined: Mar 2007
Posts: 2,579 Threads: 43
 Dave's Country Flag  View Dave's 6 photos
Amherst   Wisconsin
Dave is on a distinguished road
Default

Well, the '73-76' motors are some of the worse. Down to 8/1 compression from 9/1 you had before. Think the crank timing is retarted also. Going to the GT-40, which do flow a lot better, is going to further drop your compression ratio. I'm guessing down to about 7.5/1. Could mill the GT-40's heads to get some of that back, not sure how much.
Dave
__________________
2013 Stage 3 Roush
'66' Ranchero w/almost done 302 T-5 swap
2000 4x4 Ranger
2003 4x2 Ranger
'69' Fairlane Cobra, 428 4-speed waiting for work
Dave is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-07-2011   #5 (permalink)
Blainer is offline Apprentice

5.0L Member


Joined: Jan 2005
Posts: 144 Threads: 10
 Blainer's Country Flag  View Blainer's 34 photos  View Blainer's HomePage
Medicine Hat   Alberta
Blainer is on a distinguished road
Default

worse heads were the 255(4.2) v-8 heads.
Blainer is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-07-2011   #6 (permalink)
Pig Muffin is offline GT Member

Classic Member


Joined: Sep 2009
Posts: 1,555 Threads: 90
 Pig Muffin's Country Flag
Amelia / Cincinnati   Ohio
Pig Muffin is on a distinguished road
Default

Quote:
Originally Posted by Dave View Post
Well, the '73-76' motors are some of the worse. Down to 8/1 compression from 9/1 you had before. Think the crank timing is retarted also. Going to the GT-40, which do flow a lot better, is going to further drop your compression ratio. I'm guessing down to about 7.5/1. Could mill the GT-40's heads to get some of that back, not sure how much.
Dave
why would gt-40's reduce the compression ratio? The gt40's are 61cc what are the stock 302 cc volume?
__________________
1968, 302 .030 / Comp Cams Magnum 270h #31-414-3 501 lift @ .050 dur 224/224
Comp Cams Magnum Lifters and Pushrods Comp Cams 1.6 Full Roller Rockers
Edelbrock RPM heads (2.02 / 1.60) / RPM Air Gap
Holley Street Avenger 670 carb
Edelbrock 110gph Fuel Pump
Cloyes Street True Roller Timing Chain / Professional Products Harmonic Balancer
MSD Pro billet Dizzy, 6AL Box, Blaster 2 Coil
Flowtech Long Tube Headers
Pig Muffin is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-07-2011   #7 (permalink)
Sick467 is offline GT Member

Classic Member
V6 Member


Joined: Aug 2009
Posts: 2,038 Threads: 141
 Sick467's Country Flag  View Sick467's 69 photos
Sedalia   Missouri
Sick467 is on a distinguished road
Default

I think the 76 302 where 58.2cc. If that is the case, seems like using the 76's it would have higher CR, even though slight. I'd still choose the GT40's and mill them to your desired CR. Although before you go sinking money into rebuilding heads - there are some good cast iron aftermarkets for 1000$.
__________________
Ride On,
Noel

"I'll fix it or break it, Guaranteed!"
Sick467 is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Unread 09-07-2011   #8 (permalink)
t.mcginley.jr is offline Made Member

Classic Member


Joined: Sep 2010
Posts: 454 Threads: 43
 t.mcginley.jr's Country Flag  View t.mcginley.jr's 2 photos
South Jersey   New Jersey
t.mcginley.jr is on a distinguished road
Default

theres also brand new edelbrock aluminum e-streets for $900ish from CJ Pony Parts (cjponyparts.com). when they have a sale they go down to $836

talk about breathing better... aluminum cnc heads >>>> cast iron 302 heads from any year ever
t.mcginley.jr is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Sponsored Links
Advertisement
 
Reply   Post New Thread



Thread Tools



Mustang Photos
Mustang Links    Top Sites    RSS    Link To Us    Add to Favorites    Archive    Terms of Use    Site Rules    Privacy    Contact    Sponsors    Advertise   
AllFordMustangs is not affiliated with or endorsed by Ford Motor Company. ©Copyright 2002-2011 All Auto Enthusiasts Network

Search Engine Friendly URLs by vBSEO 3.5.2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164