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Volvo Engines

I have collated some additional information on Volvo Engines, mainly for the 211A [Chevy V8], from various sources. I would like to remind you of the Disclaimer on this website before reading any further.

Fuel Consumption

Engine Type Max Fuel Consumption at Full Load Overall Cruising Consumption
Litres/Hr Imp Galls/Hr Litres/Hr Imp Galls/Hr
AQ125 32.95 7.25 18.95 4.17
AQ131 30.00 6.60 22.00 4.84
AQ145 39.95 8.79 21.95 4.83
AQ151 43.00 9.46 30.00 6.60
AQ171 48.20 10.60 22.60 4.97
AQ175 49.94 10.99 23.99 5.28
AQ200 57.81 12.72 31.81 7.00
AQ211 60.00 13.20 42.00 9.24
AQ225 65.00 14.30 45.00 9.90
AQ231 65.00 14.30 45.00 9.90
AQ260 79.85 17.57 45.99 10.12
AQ271 92.80 20.41 37.10 8.16
AQ290 92.80 20.41 37.10 8.16
AQAD30A 27.81 6.12 17.36 3.82
AQAD31A 29.40 6.46 18.90 4.15
AQD40 35.95 7.91 23.95 5.27
AQD41A 34.60 7.61 22.00 4.84
AQAD40B 43.76 9.63 28.40 6.25
AQAD41A 47.20 10.38 33.00 7.26


DP series drives - will give a 15% (approx) increase in distance covered for fuel used OR faster top speed, but not both at the same time! 

Cruising: My assumption is that 'Cruising' means 300-500rpm below rated maximum.

Rochester 2GE Carburettor Settings 

Idle Mixture Setting

Conventional Idle Mixture Screws that provide a leaner A/F when turned clockwise and richer A/F when turned counter clockwise. The idle speed is controlled by a conventional screw that opens the Primary Throttles. The following procedure should be used to set the idle mixture and speeds - if you prefer you can move each Mixture Screw by equal amounts but the following procedure does take into account slight differences between the two barrels. An initial setting of 1.5-2.0 turns out from light seating to start the engine.

RPM Method

 Fully warm engine, ensure choke is fully open and air cleaner is in place.  Set desired idle speed with the throttle screw. [Volvo Specs for 211A = 600-650rpm - I set this speed with drive in gear as I have had stalls when docking! In Neutral the idle speed is 750-800 rpm]

 Adjust the Idle Mixture Screws on ONE side to get the maximum possible RPM. Do not go rich beyond the maximum speed point. If this changed the idle speed more than 40 RPM, then readjust the speed. Adjust the side OPPOSITE of that in Step 4 to get maximum RPM and Reset the speed. Carefully trim each Idle Mixture Screws to again get the maximum idle RPM. Go leaner just enough to get a 20 RPM drop in speed. Reset the speed to the desired RPM.

This is a Lean-Best Idle Setting. Setting richer than this will not improve idle quality or performance, but could tend to foul plugs. The Chevy V8's are quite susceptible to fouling and there is a performance enhancement suggested by Mercruiser Master Mechanic Dennis Moore, with reference to all Chevy Marine V8 units, to change the standard spark plugs to projected nose plugs - Engine Tuning for Maximum Performance

Vacuum Method

There is a blanking plug on the inlet manifold which can be removed and a vacuum takeoff fitted. Vacuum should be 14-16 Hg at Idle.

The best way to set the idle mixture is to lean the carb out until the vacuum just starts to drop, then richen the mixture by about 1/4 turn. If you have a bit of a stumble in very light, low speed operation, sometimes it helps to richen it up by another 1/4 turn.

Idle Speed AdjustmentA common cause of non-responsive idle mixture screws is having too much (more than .040 inch) of the idle transfer circuit exposed.  The idle circuit allows a very small amount of finely metered fuel into the engine.  By exposing the transfer circuit too much, the gross feed of fuel coming out of the transfer circuit overpowers the fine amount coming out of the idle ports. If your engine is worn, or has a big vacuum leak, you should fix those problems before trying to fix your carb.  Sometimes, with worn engines or one with a vacuum leak, the carb must be opened quite a bit just to get the engine to run.

Excessive fuel pump pressure: Avoid extremes in fuel pressure. At IDLE, there should not be any more than 6.0 psi; if the vehicle has an adjustable fuel-pressure regulator, set it to 5.5 psi. With most fuel pumps the minimum fuel pressure is encountered at max rpm. Fuel pressure should not drop below 2.0 psi. If it does, a fuel pump with more capacity may be required.

Fuel is flowing out of places it should not: The symptoms are a periodically terrible idle that may have coincided with an instance of full throttle and may similarly go away after another instance of full throttle. The motor will sputter and die at idle and fuel will continue to flow from the discharge nozzles after the engine has died. Sometimes fuel will leak through the throttle plate hinge shaft bores to the outside of the carburettor and onto the manifold!

Needle and Seat: This can be contamination preventing the needle from seating properly and causing a flooding or overfilling of the float bowl. The cure for this is to rebuild the carb and replace or adjust the needle and seat. Remove any debris from the float bowl and check or replace the fuel filter. The float valves (inlet needle and seat assemblies) should be replaced every 5 years max. Float valves have viton rubber tips (most cases) and rubber o-rings that can go bad, especially when they sit around for long periods [Eg. a boat stored for the winter].

Excessive Fuel Level: This is most likely due to a bad float valve, bad float, or excessive fuel pressure.  The first step is to check the fuel pressure [see above].  If the fuel pressure is correct, either the float has sunk, or there is a problem with a float valve.  If you have black nitrophyl plastic floats on a carb over 5 years old, the float may be soaking up gas and sinking.

Rochester 2GE Rebuild Kits [Sierra?] are available from: [prices are excl Delivery & Tax]

Keypart [UK] - 67.56.  Float - 7.42

The Shad Connection [US] [Sierra#187086] $22.77.  Brass Float $8.76

Other Sources of Information:

Engine Tuning for Maximum Performance - Article by Dennis Moore about getting the most out of a Chevy V8 Marine engine. - Site provides some good tips for Volvo's and Mercruisers.

Revised: 26 Jun 2008 12:09