Re: [AMC-list] 4 barrel intake for a 290

[Ken Ames <ameskg@xxxxxxxxx>]

A 290 at 5000 rpm would flow about 420cfm at 100% volumetric efficiency. 
Still, the 4bbl 290 was rated at 25 more hp than the 2bbl, about 12.5%, and about 5.3% more torque. 

Ken

----- Original Message -----
From: "Dan Ritzinger" <danritz@xxxxxxxxxxxxxxx>
To: "Rambler AMC, Nash, Jeep and family" <amc-list@xxxxxxxxxxxxxxxxx>
Sent: Wednesday, February 11, 2015 6:49:33 PM
Subject: Re: [AMC-list] 4 barrel intake for a 290

Wow, thanks for all the info, Matt, I really appreciate it and will pass it 
on!

-----Original Message----- 
From: Matt Shumaker
Sent: Wednesday, February 11, 2015 7:39 PM
To: amc-list@xxxxxxxxxxxxxxxxx
Subject: [AMC-list] 4 barrel intake for a 290

Be careful about what intake that you select.  I saw a list member
offering a 4 barrel intake from a 1978 Matador.  (Those are RARE, BTW.)
If my memory is correct, the 1969 290 would likely have maxed out with
the 2 barrel carburetor.  A 4 barrel carburetor might have provided too
much fuel and insufficient air.  In 1969, again working from memory, I
believe that the 2 barrel might have been a MotorCraft 2300 and the 4
barrel for the V8s would have been a Motorcraft 4300.  I could be way,
way off on the carburetor models, because my knowledge is current as of
the 1971 models and I am sort of thinking backwards here.  Prior to the
change from 290 to 304, they might have been Holley carburetors.

The 4 barrel intake from a 1978 Matador would be for a spread bore
Motorcraft 4350.  I am very, very familiar with both the intake and the
carburetor.  I like both of them.  But they would be extremely difficult
to tune for a smaller-displacement V8 like the 290. Significant
re-jetting would be needed, if it was even possible. The 4350 uses a
variable jet system that's based on throttle position.  It can be tuned
a little bit, but it seems to work best for the 360 to 401 cubic inch
V8s.  Then there is the really daunting task of finding a Motorcraft
4350 that is in decent condition.  Those I've seen in the rebuilt boxes
are generally on their last legs, and, really, just crap.  I found that
I had to rebuild them again because the main body had warped over time
and I had to file the top flat.  Motorcraft made a significant change to
the main body between the 1976 and 1977 model years that requires
different main body to air horn gaskets.  But any more, repair kits only
come with the 1977 and up gasket, which will cause a fuel leak onto a
hot part of the engine if great care is not taken while assembling the
carb.  Then AMC used a fibrous insulating gasket about 1/2 inch thick
that goes between the 4350 and the intake that is designed to reduce
vapor lock and fuel boiling.  Those can be hard to find, but some kits
have them now.

Edelbrock makes an intake that'll drop in.  Believe it or not, the AMC
dual-plane 4 barrel intakes actually flow better.  That tidbit was given
to me by an Edelbrock engineer some years ago.  Another possibility
might be to find one of the early 4 barrel intakes that'll fit.  (Be
double certain sure to get the mating surfaces lightly touched up at a
machine shop to prevent leaks.)  Then find a Weber or a Weber clone and
estimate the jets you'll need.  A lot of work.  If someone on the list
has made the swap, I'll go away now, and eat worms in the garden.
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