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MG MGB Technical - How RED shoud the converter get

While hunting down food lockers of various critters that had moved into my B before I bought it recently, I discovered something I hadn't noticed before.

The catalytic converter on the 80B is right there conveniently located below the carb behind a rotting heat shield (soon to be replaced).

Now I know converters get rather hot, but should they actually glow?

I had this happen once to an old barrel stove(made from an old 55 gallon drum) in a log cabin. Woke up in the middle of the night and looked at the barrel stove to see it glowing orange to red; I'd swear I could almost see the logs burning inside. I didn't think this was a good thing, so I dampered the fire down to decrease the heat.

When working for the Federal government, we used to have these mini pickup Dodge trucks, with converters that would catch fire when parked over dry grass or crops. We got rid of those trucks.

Now I see my converter glows a nice orange to red on the front area. I typically don't get under other cars to see what color converters are glowing, so this is new to me.

Is this normal?
R.W Anderson

Might check your other thread
Dan Craig

Yup, I see someone did comment that they do glow and there is a recommendation to gut out the converter. I think I may simply replace the heat shield when I take carb off for anything.

Oh, and try never to drip anything down onto the converter.

It is a nice location though, tucked up where little air can get to it for cooling.
R.W Anderson

Actually, the glow is telling you that there is an issue. Over-rich mixture or air pump failure to divert are most common probs. Slip the air pump belt off and see if a difference is made. Choke remaining on or loose screws in the choke housing make for many over-rich conditions. Gutting the cat gives you some margin for error without having a wienie roast under the hood. Fix this issue first - for safetys sake. Dan
Dan Craig

Also, the honeycomb structure, that holds everything together inside the converter, can collapse over time and eventually block off your exhaust gasses completely. RAY
rjm RAY

Watch out for the choke! There is a brass fitting on the bottom of the choke housing. This part has been known to fall out dripping gas on to the catalytic converter. I used to see a lot of late model Bs with burnt paint mark in the middle of the hood. It was from this. The ones that burned totally were from this and the hood pull broke off letting the fire rage under the hood.

Good luck!
Steven Devine

After several looked over my 80B yesterday, the recommendation was to take several things off the car, starting with the fuel safety switch that is located on left fender near fire wall. Apparently they are prone to leaking and then it is just a matter of time before the gas the and the convertor meet up, and one has a nice fire.

Which explains the burnt paint on a fellow club member's car at that location.

It has been suggested I get a exhaust pipe for a 75B that doesn't have the convertor on it.

More later, of course.
R.W Anderson

This thread was discussed between 27/06/2013 and 07/07/2013

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