390 valve sizes
New User
Joined: Jan 2008
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390 valve sizes
390
66-71 IV = 1.558
66-71 IV = 1.561
66-71 EV= 2.027
66-71 EV = 2.030
Dennis
Oh....Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
66-71 IV = 1.558
66-71 IV = 1.561
66-71 EV= 2.027
66-71 EV = 2.030
Dennis
Oh....Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
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Senior User
Joined: Dec 2000
Posts: 435
Likes: 0
From: Nebraska Farm
390 valve sizes
Does that mean there were two sizes or am I missing something? Also, that seems awfully big, why is there such a big deal about the 428CJ valves and being 1.65 instead of 1.55 (I did some searching on past posts)
New User
Joined: Jan 2008
Posts: 0
Likes: 24
390 valve sizes
This was right out of the Speed Pro Reference/Application Book
Dennis
Oh....Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Dennis
Oh....Please Don't Ask Me Any Tough Questions As:
"I'm Saving Up MY Memory For When I Develop Alzheimer's"
78 F-150 429CJ C6 ,Silver w/Explorer Pkge
641/2 Mustang,Pre-World's Fair Car #8092
64 Fairlane S/C waiting for a 390-4spd.
68-Mustang.Sunlit Gold 80,000 miles
Thread Starter
|
Senior User
Joined: Dec 2000
Posts: 435
Likes: 0
From: Nebraska Farm
390 valve sizes
I found my book at home last night, it said intake 2.04 exhaust 1.566.
Its the yellow Ford Performance book. If you don't have it or haven't seen it, its packed with info on virtually any engine Ford built. Its even got 2 pages on the 427 SOHC.
Its the yellow Ford Performance book. If you don't have it or haven't seen it, its packed with info on virtually any engine Ford built. Its even got 2 pages on the 427 SOHC.
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
390 valve sizes
Dave, the big deal with the CJ valves is flow area. The power the engine uses to pump the exhaust out reduces what is left at the wheels for you. The std 1.55 390 exhaust valve has 1.88 square inches of area. The 428CJ 1.65 valve has 2.14 square inches of area, about a 20 % increase in are available for flow. The big 1.75 427 exhaust has 2.4 square inches of area. Letting the engine breathe easier means more power for you. Adding the bigger exhaust valves is worth about 20 hp on a 390. And thats all across the curve, not just at the peak. The bigger intakes only add 7-10. That is because the FE needs help with the exhaust, the intakes are pretty good just as the factory made 'em. DF
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