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The Holley 500 CFM 2-BBL #4412

The Holley 500 CFM 2-BBL Part #4412 Two-Barrel Carburetor is a great improvement in
power over the stock Carburetor GMC Used. These parts can be found at any good parts
house like NAPA or CarQuest, or from Places suppliers online like JEG's High Performance.
You will Also need an Adapter to mount it to your manifold. Mr. Gasket Adapter #720-1937.
NAPA used to sell a Large Stromberg to Holley Adapter, It was Balkamp part number
735-1228. A check of NAPA's national parts finder service don't show any in inventory
anymore. Guys in the small towns that have good NAPA's that have been around a
long time might want to check, you never know, you mite fnd one.

The Holley 500 Project

as done by Dennis Arseneault
Swap the Stromberg for a Holley to give the big 351E the carburetion it deserves.
The 351E intake manifold has a different bolt pattern than the 305 V6.
To bolt the Holley carburetor to it an adapter is needed.

351E intake & Stromberg WWC carburetor

1966 GMC 351E Intake Manifold

This is the intake for the 351E V6 after it
has been removed. It will be sandblasted.

351E Intake Manifold After sandblasting
The intake is ready for primer & paint.

Conversion Kit, A custom machined adapter was
made of aluminum. 2 gaskets, 4 nuts, 4 washers,
4 studs & 4 bolts secure the carburetor.

Ready for installation, the manifold is Painted
with high-heat engine paint & is ready for install.

After placing the gasket on the intake, the
custom machined adapter is mounted using
the 4 allen head bolts.

The carburetor gasket that comes with the new
Holley carburetor fits nicely atop the
custom machined adapter.

Look how nice that Holley carburetor looks atop
that 37 year old reborn intake!

To connect the fuel line you must remove the
filter & parts on the left & replace them with
a #6 90 degree push-on aluminum hose end, part
number 239006 # a 36 Holley 7/8" -20 dual feed
fitting, part number 700106. Both parts are
from www.XRP.com.

The fuel fitting & fuel line connected to the
carburetor. An in-line fuel filter replaces
the filter that was removed.

To attach the accelerator you need to purchase
this return spring & mount it. Mounting it
requires using a longer bolt than the one that
comes with the return spring kit.

Installed & ready to go! The stock choke cable
has been replaced with a Holley aftermarket cable.
Everything is attached & ready to go.

1966 1500 w/351E V6, 4 speed transmission in the
Desert at South Mountain Park in Phoenix, AZ.
See ~~> Full Size Photos <~~ There

Here's how Clay Chilton of Colorado Springs installed one on his 351E:
"I took the old carb off & marked the length of the four blots at the base of the intake manifold
& then unscrewed them with channel locks. then I put them in a vise & cut them off just shorter
than the marks with a sawsall & then used a sawsall to make a flat head notch to screw them in. I
then screwed them in to just below flush & sealed the tops with some high temp silicone. Then I
placed the adapter on the manifold & centered the center hole & marked the the four bolt holes,
There was just enough space, then I drilled four new 1/4 inch holes & tapped them with a 5/16"x18
thread tap & bought four new 5/16x18 thread screws at the hardware store. I left the intake manifold
on & used a magnet, rags & vacuum to catch the metal shards, but I would recommend taking the
manifold off if you can find the gasket kit. This all took maybe two & a half hours & was
defiantly worth it! The only other thing I had to do was replace the jets due to living at 6500 ft."

GMC V6 Manifold Info & Photos

The 305B, 305C, 305D & 702 2-BBL Maniflod can
use the Mr. Gasket Adapter #720-1937 to mount
the Holley 500 CFM 2-BBL 2300 Model
Two-Barrel Carburetor. Other brands
of Adapters; CP Automotive ~ #40203.

The 351E, 351M, all 401, 432 & 478 V6 engines use
a trapezoid base, so the #720-1937 adapter won't
work unless you use Clay Chilton's method above &
redrill the holes in a wider position. Trans-Dapt
used to make the proper adapter part # 2140, its
been discontinued. You can use a 305 or 351C intake
manifold, though it has smaller ports it will still
work on a Magnum head V6s.

If you have the 1960-61 305A you will need a differenet
Manifold from a newer engine, as this engine had a 1-BBL
Carburetor with the little single hole mount.

The GMC Twin-Six manifold is a lot like the 305B, 305C,
& 305D manifold, only has has the V12 firing order on it.

Performance Upgrades For
Your GMC Big Block V6

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