I have a stock 455 that has a set of small valve 400 heads (#45) on it & i have a set of 4x heads that i am thinkin about puting on it, what would i gain or lose with this thade?

I have a stock 455 that has a set of small valve 400 heads (#45) on it & i have a set of 4x heads that i am thinkin about puting on it, what would i gain or lose with this thade?

They both suck. You gain nothin.

I learned the hard way...I had a set of #15s with 1.96 and 1.66 valves....tried making them 2.11 and 1.77 and porting them out....too much trouble, not worth it. Just buy some good 6X's with the big valves and port the sonofabitch out. Go to www.pontiacwarriors.com and check out some of the dyno runs with the heavily ported 6x heads

Project: Black Hawk
See the saga unfold here: My 455 Firebird
2001 Camaro Z28 6-speed: [email protected] stock cam, stock heads, stock rear, stock clutch

4X's are a predecessor to the 6X (so to speak). They're a better choice than what you have now. What are your goals?

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My goal is to keep it as a every day driver, and a stand by for the strip when my bird is down. I dont have alot of cash to sink in all my cars and i have thease heads already. just cleaned up the 4x heads and thought i would post the swap just to see what kinda feed back i would get. thanks to all

Get a set of 5C's. They're the same as the 6X's, but everyone thinks they're junk. You can score them for little dough. http://forums.performanceyears.com/g.../icon_wink.gif

I'm like heaven, everybody wanna get to me.........

Thanks for letting the cat out of the bag bruce! http://forums.performanceyears.com/g.../icon_wink.gif

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WHO LIVES IN A PINEAPPLE UNDER THE SEA.....

With all the aftermarket heads out/coming out now, its no longer cost effective to use the factory cast iron stuff. No more secrets, my friend. http://forums.performanceyears.com/g.../icon_wink.gif

I'm like heaven, everybody wanna get to me.........

Lots of versions of 4X heads. If the 4X heads are 2.11/1.66 from a 400, go for it. They will be around 98cc. If they are 114cc from a 455, you will be able to pee in the gas tank and still run OK. 4X's flow about as well as 6X heads.

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