400 2 barrel v 400 4 barrel

[redgum78]

73 charger. Apart from 2 extra barrels was there any other difference between the two 400ci engines?

[heyoldguy]

I cannot find my '73 book but according to the '72 manual the only other changes were distributor timing, camshaft, valve springs and as crazy as it my sound.......valve stem diameter!

[John_Kunkel]

The '73 400-4 was a HP engine......same HP parts (cam, springs, exhaust manifolds) as the 440.

Different valve stem diameter? Uh-uh. 

[heyoldguy]

From the 1972 FSM.

Intake valve stem diameter, 400-2bbl and 440 standard,  .3723"-.3730".
......................................400HP, 440HP 440 3x2bbl .3718"-.3725".

Exhaust valve stem diameter. 400-2bbl, 440 std, Hot end .3713"-.3720", cold end .3723"-.3730"
........................................400HP, 440HP, 440 3x2bbl hot end .3708"-.3715", cold end .3718"-.3725"

John, You can roll your "smiley eyes" all you want, but that is what the FSM says.

I have measured stock valves and gotten different stem sizes. I never tied it to standard or HP engines.

[LowDeck451]

Interesting, it must have saved a machining step, finish all the head castings identical, then just drop in the 'skinny' valves for the HP motors.

[John_Kunkel]

Those aren't "different" valve stem diameters (like 11/32" or 5/16"), they're just acceptable tolerances for the nominal .375" stems that have been standard on all BB's since '58.

[redgum78]

Thanks guys, I was thinking of sticking a 4 barrel and a set of header on mine (currently 2 barrel). Was just curious what else the factory 4b had in addition.

[Nacho-RT74]

Valve springs with dampener
Windage tray
4 bbl intake
HP exhaust manifold
HP cam ( although detuned year after year )

[heyoldguy]

Thanks guys, I was thinking of sticking a 4 barrel and a set of header on mine (currently 2 barrel). Was just curious what else the factory 4b had in addition.

Here, this might be interesting 2bbl vs 4bbl reading.

http://www.forbbodiesonly.com/moparforum/showthread.php?80843-The-slug-400-on-the-dyno&highlight=400+2bbl

[redgum78]

Thanks guys, I was thinking of sticking a 4 barrel and a set of header on mine (currently 2 barrel). Was just curious what else the factory 4b had in addition.

Here, this might be interesting 2bbl vs 4bbl reading.

http://www.forbbodiesonly.com/moparforum/showthread.php?80843-The-slug-400-on-the-dyno&highlight=400+2bbl

Thanks for the link. Looks like it loved the 4 barrel! I have a 4 barrel on another engine that's not going be used for some time. Thinking I might slip it on and see what difference it makes.