design - Land Rover section

 

Land Rover FAQs

 

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 carbrettor 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 instnce 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 disolves 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.

  1. 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. 
     
  2. The engine has to be healthy and should have at least the 8:1 compression head, preferably 9:1 compression.
     
  3. 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.
     
  4. 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.
     
  5. 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.
     
  6. Use an intake manifold designed for the carb and not just a carb adaptor 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.
     
  7. 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 rebuildning 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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