Re: Carb for my 304

[jlandry@domain.elided (John A. Landry)]

When he stopped taking his medication, strange voices in Ben Cole
<bcole@domain.elided>'s head said:

>So I definatly have a 304 in my 68 Travelall and I need a new carb for it.
>Sould I get a rebuilt 2300 or a new 2300 universal and if I get the new
>carb should I get the 357 cfm or the 500 cfm?

Ben,

You don't need a 500 cfm carb on a stock 304.  If you have a choice,
install the 357 cfm carburetor.  Over carbureting an engine is *the* number
one mistake people make when adding aftermarket parts, second only to
installing a too radical camshaft.

Because of the design of a two-barrel carb, it's even more critical that
you do not install one which is too big.  This is because the same venturi
must properly meter the air / fuel mixture from low rpm all the way up to
wide open throttle.  The venturi have to be sufficiently large to meet all
engine cfm requirements, which means they are fighting conflicting demands
and are a compromise.  On the other hand, a four-barrel carb is a little
more forgiving because only two of the venturi are used for low rpm / part
throttle operation, so they tend to be smaller and do a better job metering
in the air / fuel mixture.  So a four-barrel carb which is slightly too
large for and engine's cfm requirements is not as big of a problem.

What happens if you install a too large carb?  Possibly nothing, but
possible poor part throttle response and less the optimum fuel economy.
Drivability will likely suffer on the low end.  You could get bogging and
increased exhaust emissions during part throttle operation.

Just so you know... the *factory* installed an approximate 350 cfm carbs on
stock 304's and 345's equipped with two-barrel manifolds.  Don't be
swayed... bigger is *not* better with carbs... especially a two-barrel...
and IH knew what they were doing!

Good luck,

John L. 
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