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Author
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Topic: GT40 heads
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indyphil
Gearhead Posts: 2354
From: Senoia, G.A. USA
Registered: Jul 2002
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posted 04-15-2003 05:52 PM
   
I may be in a position to buy some brand new GT40 heads for my 289. New, still in box but second hand for less than new money. what do I need to know about pedastal rockers and my 289? Can i convert them to run the early style rockers? Should I? Im new to the valvetrain stuff.I think it will lower compression so is it worth it or should I buy the roush 180 heads ive been thinking about. Although I have a 68 289 engine, it currently has 66 heads on it (9.5:1 compression) any insight is appreciated. ------------------
'68 coupe 289 C code
66 heads, edel 600cfm carb, performer intake, dual exhaust
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SteveLaRiviere
Administrator Posts: 42859
From: Saco, Maine
Registered: May 99
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posted 04-16-2003 06:15 PM
It'd be smart to use the new roller rockers with them. Have you compared chamber volumes to see exactly what your compression ratio would be?------------------
'70 Mustang Mach 1 - '72 Mustang Sprint - '94 F-150 Please remember our sponsors,
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Moneymaker
Administrator Posts: 25539
From: Lyons, IL, USA
Registered: May 99
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posted 04-17-2003 09:53 AM
It will cost you about $160 to machine the heads for stuf mount rockers.
You can buy pedestal mount adjustable rockers for the GT-40 heads.
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Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
MCA member# 53321
NHRA and IHRA SS/LA National Record Holder '00,'01,'02,&'03
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Professional Manwhore
The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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Huskinhano
Journeyman Posts: 57
From: Montvale, NJ.
Registered: Nov 2002
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posted 04-18-2003 07:36 AM
The GT40 heads have a volume of about 65 CC's or about 10 CC's more then your heads right now. This will drop your CR by about a full point, roughly.You can modify your heads as moneymaker said or use the late model bolt on rockers and pushrods. You can get bolt on roller rockers. I belive Comp Cams sells adapter studs that have the 5/16 thread for the head and 3/8 for the rockers. I think this will be ok for stock valve springs and mild cams but i don't think I'd want to use it for much more. Before you leap into this project, estimate how much it's going to cost for everything. Maybe it'll be more cost effective to put 351W valves and do a little pocket porting to your present heads!
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