Extinguisher works - Weber warning

[Old Septimus]

Yesterday morning my 7 caught fire in a big way whilst I was doing a fair speed on a B road. After a strong chemical smell within a few seconds flames 2 feet long were coming out of the intake scoops and spreading over the bonnet. I pulled up and exited the cockpit like a cork from a bottle with a Firemaster 600g extingusher which I carried clipped to the bulkhead on the passenger side. I sprayed this through the scoops and the fire seemed to be out and so I got the bonnet off and there were still some small flames around the dynamo area which I got out with the last of the powder. The reason was that the brass pipe into the top of the float chamber on the Weber downdraught carb had pulled out of the casting and had pumped fuel all over the engine. This seemed pretty tight when I last fitted the flexible pipe to it earlier this year but is now a very slack fit. There doesn't appear to be much to keep this in place apart from the interference fit.

 

Damage seems to be limited to "soft" items like the clutch pipe, oil filler cap, battery caps, expansion bottle and advance pipe. The wing and nosecone are a bit bubbled. The flames obviously blew back and up within the bonnet and don't seem to have got to the wiring. Inside very messy with greasy black soot and powder. It's got to go to France next week and so work cut out. Suggest you check these pipes on oldish carbs and buy an extinguisher (and carry it). Otherwise my 7 would have been totally written off.

[allen]

I guess this is the single webber instalation with the bonnet bulge/scoop?

 

Not the twin 40's, which have a banjo fitting bolted onto the carb, i.e. not a push fit.

 

Yes?

[Peter T]

Sounds exactly like the problem i had a few yaers ago, on my 1600E cortina, the brass inlet pipe on my 28/36dcd Weber carb parted company at 40mph, by the time the float chamber had emptied itself of fuel, nearly 2ltrs of fuel had sprayed onto the hot exhaust! Voila one meaty under-bonnet fire. luck would have it, i was carraying a freinds fire extinguisher from a car he had just sold !

 

On The Starting Blocks!

[Old Septimus]

Yes, it's the twin choke single downdraught with the bonnet scoop on the top, not twin DCOEs. Because it's a Lotus and not a Caterham the bonnet has the side scoop on the N/S where the pre-crossflow Kent engines had their carbs. This was where I sprayed the extinguisher. Not sure what I would have done without this as no bonnet louvres to spray through.

[Peter T]

Yes as you say, it only applies to Weber downdraught carbs and not the Dcoe variants. The brass inlet union is only a press fit, and through time it becomes loose, after my fire i bonded the unoins in with arraldite!

 

On The Starting Blocks!

[stevefoster]

Not good to hear. Fire is aways a concern isn't it.

Hope you get it running in time for France...

 

 

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[Graham Sewell]

I had the same problem on an old Cortina, except that I noticed the smell very quickly and stopped the car before the fuel found a spark. Pushed the union back and drove home where I liberally applied a hitting stick to this joint.

 

Low tech luddite - xflow and proud!

[Westfield]

 

 

I have seen this many times in the past on cars with this type of carburettor. Reliant Scimitars were also particularly prone to it! The most effective modification I have used is where the brass push in pipe is removed and a brass washer/collar soldered on whereby it can later be safety wired in place. I always allow the solder to “tin” the pipe so that it is a tighter fit as its bushed back into the carburettor.

 

On the subject of fire extinguishers I never work on the car now following an incident in the garage a couple of years ago. I was doing some work on my Lancia Thema when I removed what I thought was a small water pipe. It turned out to be a fuel pipe under pressure. As I undid the clip and pulled on the pipe it came off and sprayed petrol under the bonnet and down the back of the engine. I had a small electric fire on the floor and as I turned around to switch this off, the petrol ignited.

 

The results were frightening to say the least as flames engulfed the engine and set fire to the under bonnet material. By sheer luck I had always kept a small fire extinguisher on the back of the bench that I had acquired some 15 or more years previously. I had actually found it in the boot of a car in a scrap yard! Thank god it worked! Although after all that time it had very little pressure in it, but enough to extinguish the flames. What amazed me was the smoke in the garage from such a small fire. I actually thought the lights had fused; it went so dark so quickly.

 

This was the first time in my life when I actually went into shock!

 

Needless to say this prompted me to buy a decent couple of fire extinguishers that are kept in the garage and the kitchen…

 

[Neil F]

Some advice in case you don't already know.

You should avoid touching anything with your bare hands that appears burn't especially if it is a rubber or plastic based component. The sort of thing I mean is rubber and plastic hoses and windscreen rubbers etc.

The reason is that they often leave behind a carcinogenic residue that can be absorbed into the skin.

I believe it is the result of a compound used that has something to do with the perish resistant properties of these types of rubber/plastics to combat their contact with oils and exposure to heat.

I'm not trying to scare, only help!

 

Neil.

 

(P.S. I think my Profile Signature has particular relevance here 😬 )

 

Better to burn away and fade out, than to burn out and fade away....