>My brother in law is fitting a 4bbl Holley to his Land Rover Stage 1 V8.
The engine is the
>standard 3.5L carb model. Does anyone have any suggestions on the best
inlet manifold to use?
>It would be good if its available in Aust. I can't remember if the holley
is a 350 or 450 - does
>anyone have ideas on what the best one would be. It will make his day if
all the suggestions are
>different to what he is getting!!!! The Land Rover is used a lot in off
road driving, as well as the >usual blacktop travelling. The truck also
runs on LPG if that makes any difference.
First off, check the carb document I've been working on for the Pantera
club. So far it consists of comparison and sizing sections and I'm working
on tuning and troubleshooting sections which will be added later. I'll also
add a table of contents at the next update. Anyway, the document can be
found at:
http://www.panteraclub.com/docs/carb.doc
Be aware that you'll need Word to open the document. It was saved as a Word
97 document but next time I'll save it as HTML so it can be directly opened
by a browser.
The Land Rover is a relatively heavy vehicle for a 3.5L V8, so concentrate
on a carb and intake manifold combination that works well at low RPM. Stay
away from the single plane intakes (Offy Equa-Flow 360, Huffaker, Harcourt,
Wilpower). The factory Buick/Olds 215 4 bbl, Offy Dual Port, and Edelbrock
Performer Rover are the intakes you'll want to consider. The Dual Port is
probably the best of these for low RPM torque and fuel economy.
The small Holley 4 barrel carbs are the 390 and the 450. The 350 and 500
are 2 barrel carbs. Of these, the Holley 390 is your best bet. Be aware
that Holley makes at least 3 different 390's. List number 80507 is meant
for carb-restricted racing applications, list number 6299 is meant for 4 and
6 cylinder applications, and list number 8007 is meant for small
displacement V8's. The list number for most is stamped into the upper right
hand corner of the airhorn (a.k.a. the choke tower). On models without a
choke tower, the list number is stamped into the main body behind the
throttle linkage.
The 8007 is a 4160 Holley which means it has a plate with fixed size
orifices for metering. These plates are replaceable but cost much more than
jets. If you plan on doing any tuning (and you should), you'll want to
convert to the 4150 secondary metering block which has removable jets. The
8007 also comes with a 6.5 power valve which you'll need to replace to match
your engine's vacuum characteristics. Check the vacuum at idle (warmed up
and in gear if the vehicle is equipped with an automatic transmission) and
at various *steady* cruise speeds. The power valve should be picked to open
at 1 1/2" to 2" Hg below the minimum steady vacuum reading. For instance,
if 11" Hg is the minimum observed, pick a #90 power valve (trips at 9.0"
Hg). Note that the power valve only determines when the additional fuel is
added. The amount of fuel added is determined by the diameter of the power
valve channel restrictors (PVCR's). To properly tune the power valve
circuit to provide best power and best fuel economy, the PVCR diameters will
probably need to be altered. Unfortunately, this means making permanent
modifications to the metering block, either drilling the passages larger or
epoxing them shut and re-drilling smaller. Ben Zwissler is running around
with a Holley 390 re-worked by Ted Schumacher's Holley guru. He may have
more info but I believe they found the PVCR's to be too small. Add the
power valve protection kit while the carb is apart.
You'll also probably need to change the vacuum diaphragm spring which
controls the opening rate of a secondaries. Holley makes a spring
assortment kit (P/N 20-13) for tuning purposes. The color-coded springs run
from light tension to heavy:
White - Weakest
Yellow (Short Spring)
Yellow
Purple
Plain (Steel grey)
Brown
Black - Stiffest
A lighter spring will allow the secondary throttle plates to open more
quickly. Likewise, a stiffer spring will delay the secondary opening. To
make spring changes easy, Holley makes an inexpensive quick change kit (P/N
20-59). It consists of a two-piece secondary diaphragm housing cover which
allows spring replacement without housing disassembly.
Unfortunately, the Holley is not a particularly good carb off-road. To make
a Holley perform satisfactorily off-road, a fuel bowl conversion (p/n 34-3)
may be required. This kit which fits 4150 and 4500 models only, and
includes a spring-loaded needle-and-seat assembly (available separately
under p/n 18BP-268AS) and a spring-loaded float. Also recommended are
baffles and vent tube extensions.
As an alternative to the Holley 390, you might want to consider a Carter or
Edelbrock AFB. With it's small primaries (see table below), the Carter 9400
or 9410 (400 CFM models) would be particularly well suited to your
application but they are no longer produced. However, D&D in the States
usually keeps rebuilt models in stock. Due to their fuel bowl and float
arrangement, Rochester and Carter carbs have the reputation of being better
off-road carbs than Holleys. The spread bore Thermo Quads and Quadrajets
have particularly good reputations but they would require an adapter plate
to mount to any of the commonly available Rover/Buick intakes. Check my
carb page for details.
I don't know how LPG would affect all this, since I never messed with the
stuff.
Dan Jones
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