Welcome to our resource for MG Car Information.



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 MGB GT V8 Factory Originals Technical - Carb Iceing

I am using an Edelbrock 500 carb with K&N 2"x14" filter with Xstream Top.
Last Friday I set out at 5.15am for North Weald to take part in the Activity day run by MG's on track.
The outside temp at a guess was about 0 to 1 degree C.
The journey was 85% on the motorway. After about 60 miles the car started to splutter and run rough. I kept going for another 40 or so miles when it got so bad that I had to pull over into the services. When I removed the air filter I saw that the carb had a considerable build up of Ice around the jets.
I left the car for 20mins or so and when I re started the engine ran better but not perfect. After another 10miles the engine suddenly ran fine and was fine for the rest of the day.
I have had this problem before and it always seems to happen when Ive had an early start and the otside temp is low.
Is there any easy fix without changing the filter setup as it works so well most of the time.


I used to have a car with the same problem. The only thing that worked for me was to run fuel line de-icer in the fuel tank whenever the weather went below freezing. Any service station in the US sells the stuff, usually under the brand name HEET.

Try it.

Scott Wooley


I find a 4.6 keeps carb a bit warmer. Try to either pick up some heat to filter, or block off part of rad to keep it more cosy.


Hi, Little off subject, in your note, you mentioned the xtreme lid. Has this made a difference to the performance to the car ?. I have got a couple of the lids and the car is in storage so haven't had chance to try.


Ian Sanders


I've not measured performance with or without xstream, but as on topic I'm sure my car has been more subject to carb icing with rather than without.


Thats a good idea Ill try and rig up some sort of rad blind.
On my car the Xstream does make quite a bit of difference towards the top end of the rev range.

Ive got another early start on the 23rd when I will be setting off for Brands Hatch, I must try and get it sorted by then.



Carb icing is a real problem with aircraft engines as they operate more frequently in the conditions you discribe (near freezing in high humidity conditions i.e., clouds). Aircraft engines incorporate an exhaust gas heated muff around the carb base to keep the temperature of the carb from falling below freezing. The ice forms at this particular point because of the effect of Bernulli's principle. As the air is drawn through the carb venturi, it accelerates and cools as it approaches the partial vacuum in the manifold. The moisture in the air is first condensed and then frozen to the cold metal parts in the carb venturi. If the air is warmer, the moisture stays suspended, and if the air is colder, it passes through without condensing. Carb icing can occur at temperatures well above freezing because of this temperature drop at the venturi. This condition is seldom a problem with stock induction systems, as manufacturers have worked out methods to warm the intake air. You might try shrouding the radiator partially to raise the temperature of the engine compartment on days when these conditions exist. good luck, hope you enjoy warm weather soon!
Chris Jones (TX)

Thanks Chris.
In the winter the engine runs a bit on the cool side.
The temp guage points to 7 oclock. As I have the ST spoiler with a shroud to direct air at the rad Im gonna try blocking off the main grille completely.
I can make something up that can be removed easily and quickly at the track.


I don't know what your engine bay looks like so I don't know if it would work for you, but what if you were to duct the air passing through the radiator into the intake for the engine? This might possibly help raise the intake air temperature up a bit when the engine coolant is at operating temperature. It might look ugly, but it only has to be for winter months. If you have a clear patch of core on the back side of the radiator, then all you'd have to do is butt a piece of flexy dryer ducting against this area of the core, and then connect the other end to the intake of the engine.

Like I said, I don't know if it will work in your car or not, but it's an idea.
Anthony Morgan

Cardboard is popular for that purpose.

Jim Blackwood

This thread was discussed between 06/02/2004 and 08/02/2004

MG MGB GT V8 Factory Originals Technical index

This thread is from the archive. The Live MG MGB GT V8 Factory Originals Technical BBS is active now.