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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - Twin carb oil

Can someone let me know which oil is the best for Twin carbs on my midget mk3
raymond bossom

Some say 20/50 others say 3in1 and again some ATF fluid, take your pick.

I must say I use 20/50
K Harris

Haynes

Recommended lubricants and fluids

#8 Carburettor dashpots Multigrade engine oil, viscosity SAE 20W/50 Duckhams Hypergrade

Works for me every time

And in the back of the BL Leycare Sprite and Midget manual it states;

Recommended lubricants

Engine, synchromesh gearbox, carburetter, (their spelling!) distributor and oilcan and lists a variety of manufacturers' Multigrade 20W/50s, before going on to list SAE90 hypoid for the rear axle and steering gear.

So I rather think we'm OK to use 20W/50
Bill

Thanks Guys
raymond bossom

You know those dainty little liquid soap dispensers that "her indoors" leaves on the bathroom washbasin? They make an ideal container for some 20/50 oil, kept handy in the garage for the weekly topping up of SU dashpots.

Guy
Guy Weller

Where does that oil go?
Jeremy Cogman

I don't really know, but I always check them weekly and most times it needs an odd squirt! I always thought some oil got sucked through the carb venturi somewhere.
Guy Weller

The viscosity of this oil affects the rate at which the dashpots open. Many people put in very thin oil, like 3-in-1, Marvel, ATF, etc., in order for the dashpots to open quickly and get more air into the engine sooner when accelerating. Unfortunately, this also introduces a loverly lean mixture during acceleration as well. Delaying the rise of the dashpots makes for temporarily higher vacuum at the fuel jet, richening the mixture until the dashpot arrives at its new location. This is the reason that SU cabs do not have "accelerator pumps" to richen the mixture during acceleration like Holley carbs and Rochester QuadraJets, etc. To thick of oil can be a problem as well, I suppose, but simply putting the thinnest possible oil into stock carbs on a stock engine is not recommended. As the torque of the engine is enhanced by other mods, thinner oil can be beneficial in getting the dashpot open in sync with the faster acceleration.
David "5W30" Lieb
David Lieb

The damper oil also stops the air choke from "fluttering" during use.
Guy Weller

This thread was discussed on 11/07/2008

MG Midget and Sprite Technical index

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