Thread: 110 V8 failing the emission test

What would happen if you shut off fuel to one carb for the MoT?

Would run very lean.

Lota-A-Landy, the engine will be running on 4 pistons in a shaky manner that will intrigue the MOT personnel.

Originally Posted by lebanon

Bee Utey, this is the most interesting and easy to fit option.

correct me if I am wrong but electric solenoid valves operates either on or off. For such an application I need to be able to stage regulate the quantity of air in the inlet manifold to reach an acceptable mixture that keeps the car idling with and give the low CO reading.

Yes a solenoid is either on or off but you can add a small needle valve inline as well for the fine adjustment, even a fish tank bubbles adjuster valve might do. Suitable vacuum solenoids are used on older emissions control systems so shouldn't be hard to salvage off something. Some early EFI RRCs used them to speed up the idle with the a/c clutch. Getting the air evenly to both carburettors may involve drilling a small fitting into each carby spacer and using a tee piece between them. If you got creative you could get a 40 - 50C thermostatic switch to operate the solenoid so that the vehicle was legal whenever it was warm.

Random pics of parts off google:

Originally Posted by lebanon

Lota-A-Landy, the engine will be running on 4 pistons in a shaky manner that will intrigue the MOT personnel.

Are you absolutely sure that the air chambers to each bank within the manifold are not connected?

a 100% sure, I learned it the hard way with a leaking chock system seal that fouled 2 spark plugs on each bank.

one carb feeds piston 1,4,6 and 7 and the second carb the remaining.

Originally Posted by Lotz-A-Landies

Are you absolutely sure that the air chambers to each bank within the manifold are not connected?

Water/metho injection will lower emissions if you can get it right

You could put lean needles in the SU's when going for the test or adjust the needles lower into the jets. Also retarding the ignition will help. The air pump system was a cheap Solution back in Leyland's day & pumped fresh air onto the back of the exhaust valve & burnt the unburnt fuel in the exhaust system. A lot of the Jap manufactures used this system. I remember on the Mini's people would take the belt off to discount it but the exhaust gases would get into the pump & seize it & when they wanted to sell the vehicle they would have to get a new air pump & other parts.