This Won’t Do.

The hottest day of the year so far was an excuse for The Ambassador’s Daughter and me to try out another beach cafe, this time at Winterton-on-Sea.

Winterton-on-sea

The sun shone, the roads were practically empty and the Hillman (with a new 40 zillion volt coil) ran like a dog for most of the 130 miles there and back. The snag was that after a longish run at a steady speed, the slowing down for a roundabout or somesuch, caused the engine to miss and cough and splutter on the exit and continue to misbehave for the next couple of miles until the (indicated) temperature came down a couple of degrees again. Even then there was no guarantee of consistent running until I strapped the bonnet open with the help of my trousers belt and a bungee cord that I found in the tool bag. This  helped to get some cooler air going past the carb and reduce the temperature under the bonnet. We just made it back to the farm where of course, the engine sat and ticked over as smooth as silk.

Bonnet open

So it could have been a bunch of things. Air in the fuel line (there were some bubbles in the gascolator but the carb’s float bowl should eliminate any problem there) or fuel evaporation as the carb heats up with the transfer of the heat from the block when slowing down, rubbish fuel (I always buy the expensive unleaded) or a combination of all those things. It’s definitely not electrical as the system is producing plenty of sparks and it runs really sweetly on tick over and low revs. When it gets hot, the problems start, though, having said that, at one point in my fury I dropped it into 3rd, pushed it up to and past (an indicated) 5000 rpm where the power band comes in and it just wanted to go, pulling like a train without a moment’s hesitation.

BSA C15 engine

It’s enough to drive a chap nuts. More interestingly, I spotted this little sprint job at the local bike meet and wondered why I hadn’t had the same idea with my first motorcycle (also a BSA C15). Krazy Horse always puts on a good show and it’s very well attended. The combination of art and engineering that goes into some of the bikes on show is really inspiring.

Coventry Climax A7

As is Leon’s Coventry Climax installation in his A7. It looks and sounds fabulous and it’s only taken him about 5 minutes to complete!

Coventry Climax A7

And this is what I like…

Work in progress

… the car as an aide-memoire. That’s art. I was telling Leon about my troubles with the Hillman and describing the symptoms when something he said reminded me that the air intake to the carb is not an open bell-mouth like on the Austin, but via an air cleaner which sits on the top of the engine in the hottest part of the bonnet. I wondered if I made a couple of air scoops to help pull in cool air directly into the air cleaner gauze, it might make a difference to the running?

Fair lead mould

Years ago I made up a beech tool to press out some aluminium fairings for the Jodel control cable exits.

That’ll do.

 

 

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2 comments on “This Won’t Do.

  1. Chris Harrington says:

    Hi

    I’ve been having a similar problem, poor running when hot, with my 1969 MG Midget. The internet seems to be saying it’s “vapour lock”; I’ve had the SU carbs rebuilt by the manufacturer and it does run better.

    Did you manage to cure the problem you had with your Hillman in the above post?

    Apologies if you cover this somewhere in your more recent posts but I missed it.

    Kind regards and thanks for an interesting read, Chris

    • Hello Chris,
      Yes, I did manage to cure the problem – by fitting, 1. a new and much more powerful coil (I can’t confirm whether or not this helped – I have electronic ignition and I bought a coil from the ignition manufacturers) and, 2. by fitting a much bigger and see-through fuel filter – the cheap plastic ones commonly found on diesel engines. I think this latter mod had more to do with the cure as the smaller metal filter that came with the fuel pump, I think lacked the ability to handle the demand. The engine was good as gold at idle but when hot and wanting to go, I think it was starved of fuel.
      The Great Collectors MG TD had all the symptoms of carburettor problems – rebuilding them improved things but, the fitting of a new condenser was the key!
      Thanks for your kind comments and good luck!

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