Is a 406 just a 400 SBC bored 30 over?

I've got a set of "192" 1969 302 heads with big valves, is this a good combination of engine/heads?

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Matt86Z
~Check out my Thirdgen~
...This Ain't No Speedway!...

 

Yes, that's all a 406 is. A 400 that was worn out and has been repaired. It is not some kind of separate creation.

I don't know what you mean by "192" heads. What's the casting number?

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"So many Mustangs, so little time..."
ICON Motorsports

 

TO make a performace engine out of a 406, you need a good set of heads. The biggest intake runner on GM factory production SBC heads is 171cc. This is the Vortec design. Personally, I would go bigger. The 400 is choked off by small heads and they need to breathe. I would go at least 200 or slightly bigger. 400's are naturaly torque motors, so if the runner was just a little on the big side, it wouldn't hurt that much.



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Joshua Johnston
1991 Z-28
350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust, Dynomax Bullet Mufflers, T&R Motorsports custom air intake, Bald tires

 

Agreed. The 192 heads were feeding a 302. You're now trying to squeeze the same amount of air into a 406. It will work but you're giving up a lot of HP with the restricted heads.

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Say I'm shooting for tons of low end, wouldn't the cam have more to do with that than the heads? They've got 202/160 valves in them, I know they flow well because they were feeding the mid 13-second 355 that I had in the car before it blew up.