QUESTION - I want to put
a 32/36 DGV two venturi Weber carb on my 2.25l engine. What's
involved?
ANSWER - Think twice, better
yet think thrice before plunking down your money for this conversion.
A progressive two barrel makes a lot of sense for
both fuel economy and flexible power. That's why Land Rover
used the Weber 32/34 DMTL carburettor on the 2.25L engines from
1983 on. However
the Weber 32/34 DMTL is out of
production and can be hard to find. The
currently available "universal fit" Weber 32/36 DGV
is not the same as the DTML that Land Rover used. It has different
flow characteristics and requires different jetting. For
instance the 32/36 DGV has two fixed 27mm main venturis. The
factory used 24 primary and 25 secondary venturis on the 32/34
DTML. The 32/36 DGV flows a lot more than any other carb anyone
sells for the 2.25L engine My
personal advice is to stay away from the dgv carb unless you are
experienced with setting up DGV style Webers, have a flowed
cylinder head, hot cam and free flow exhaust. VERY
few people have ever got the universal replacement DGV to work satisfactorily
on a 2.25L engine. Note: The DTML uses a plastic float that dissolves
in fuels with alcohol. You should seek out a brass Weber flat that
will fit.
NOTE: Paul Oxley suggest that a Weber 28/36 DCD7 is a good choice
for the Land Rover 4 cyl engine. Sorry, no idea on jet sizes.
If you want a progressive 2 barrel my advice would be to hunt
down the stock 32/34 DMTL carb and manifolds from a 1983
or newer engine . The
single venturi Zenith used on the 2.25 engine is a good carb that
will give you a minimum of problems if it is in good condition. I
recommend the smallest venturi Rochester B carb if you have a "performance" built
2.25 and are shopping for a bigger carb. Simple, easy to
use.
That said, if you really want to use a dgv two
venturi Weber carb on a 2.25l engine
there are a number of things you should consider.
- The DGV is designed to be a fixed venturi progressive 2 barrel
carb. Most
people can only get the universal replacement DGV Weber to work
on a 2.25 engine with both venturi slaved together to open at
the same time. This
of course losses the flexibility and fuel economy of a progressive
2 barrel. With
both barrels ganged together you will likely be over carbureted
and end up with a big flat spot on the acceleration curve. So
far I don't know anyone who has figured out the correct jetting
for the universal replacement DGV when used as a progressive
2 barrel. It
can be set up, it just will take someone good at DGV Webers,
a good air to fuel mixture meter and a lot of testing.
- The engine has to be healthy and should have at least the 8:1
compression head, preferably 9:1 compression.
- The 2.25L cam can not take full advantage of the added flow. I
suggest converting to the 2.5L land Rover cam. The 2.5l
cam was designed specifically to work well with a 2 venturi Weber
carb. It
is a very good cam and about as good as you will find for both
low
speed off road and highway travel.
- Replace the stock exhaust with new tubing that is one size
larger diameter than stock and a lower restriction muffler. The
stock system tends to have high back pressure, esp a 109.
- Consider adding a Pertronix ignition module to keep your timing
spot on. Currently available points are not as good as
they used to be and tend to slip easily.
- Use an intake manifold designed for the carb and not just a
carb adapter plate on top of the stock 1 barrel intake manifold. You
will likely need to fabricate an exhaust block off plate. The
threaded vacuum ports are likely to be metric. Best to
use a stock 2.5L intake and exhaust manifolds.
- By far and away, your best chance for success is to source
the stock 32/34 DMTL carb, intake and exhaust manifolds off a
1983 to 1990 Ninety or One Ten instead of going the aftermarket
route. Make
sure the carb is in very good condition. Actually
your best chance is to just source the complete 2.5L engine.
Weber carbs have their main jet at the bottom of the float chamber
so you want the fuel coming in to be very clean. Consider
2 filters in series like the diesels have. Also be advised
that Webers are sensitive to altitude changes so you may have to
carry leaner jets with you if you are making large altitude changes.
Pierce recommends the following jetting for the 32/36
DGV for near sea level driving:
Part |
Primary |
Secondary |
Main jet |
140 |
135 |
Emulsion tube |
F6 |
F6 |
Air correction jet |
150 |
150 |
Idle jet |
65 |
50 |
Pump jet |
50 |
- |
Aux, venturi |
3.5 |
4.5 |
Also recommended:
Sync-link (comes with pump jet)
9151L linkage
32/36 DGV rakes Weber rebuilding kit # 92.3238.05, gasket kit
# 92.0108.05
Land Rover factory jetting for the 32/34 DMTL
|
32/34 DMTL 1
1983 - 1986 90
2.25L engine
|
32/34 DMTL 1/01
1983 - 1986 110
2.25L engine
|
32/34 DMTL 6/101
1985 - 1990 90 & 110
2.5L engine
|
Part |
Primary |
Secondary |
Primary |
Secondary |
Primary |
Secondary |
Venturi |
24 |
25 |
24 |
25 |
24 |
25 |
Idle jet |
55 |
60 |
55 |
60 |
52 |
60 |
Main Jet |
110 |
115 |
110 |
115 |
112 |
112 |
Air correction jet |
160 |
160 |
160 |
160 |
160 |
190 |
Emulsion tube |
F30 |
F30 |
F30 |
F30 |
F30 |
F30 |
Accel. pump jet |
40 |
|
40 |
|
40 |
|
Float level (mm) |
7 |
|
7 |
|
7 |
|
Needle valve (mm) |
1.75 |
|
1.75 |
|
1.75 |
|
The 32/34 DMTL takes weber rebuilding kit # 92.3006.05
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