how much HP ?
Posting Guru
Joined: Nov 2003
Posts: 1,888
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From: Iowa
i dont know what the hp on ur 390 would be with 428 heads. but in 68 the 390 with a 2 barrell was rated at 280hp and with a 4 barrell was rated at 315 hp in 73 the hp dropped do to emmisions and they also changed to net hp i believe, what year is your 390 and you said you think its a 390 with a 428 heads what are the casting #'s on the heads, i think the 428 had bigger valves im not sure on that one though, im assuming you have a 4 barrel, is it stock besides the 428 heads.
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Senior User
Joined: Dec 2003
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its a 73' 390 with a 2 barrel carb, in a 65 so there is nothing emissionswise on the engine. (pics in gallery).
I dont know what year the heads are if it even matters.
it sure does have some kick though...
I dont know what year the heads are if it even matters.
it sure does have some kick though...
Posting Guru
Joined: Nov 2003
Posts: 1,888
Likes: 1
From: Iowa
with a 2 barrell im just guessing around 290 hp might be a bit high though, im sure if the 428 heads have bigger valves that would help quite a bit, find a 4 barrell intake and carb that will get you a lot more kick than it already has. specaill with the bigger valves to give it more fuel/air thats where the 4 barrell would come in handy.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
The std 428 heads are the same heads used on the 390's. Only the 428 CJ heads had bigger valves. 73 390 2 bbl stock would be around 250 hp. do a carb swap to a Holley 500 cfm 2 bbl and that'll net you about a 20 hp gain over the Ford carb. Add headers and duals w/turbos will get you close to 300hp.
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