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MG MG Y Type - Vapour lock prevention 'project'

I've refurbished my carburettor, and "flowed" it as described in David Vizards' "Tuning the A-series engine".

At first I failed to get the car running properly and that was (eventually) traced to a wrongly supplied jet that was larger than the specified 0.09 (probably 0.10); very annoying because I missed the "2010 Y Sommertreff" because of that. But that's another story.

I've read reports that vapourlock is more common because modern fuels boil at 40 degr. Centigrade. Thus controlling underbonnet and fuel temperatures becomes more important.

I've made the following modifications, and I thought it would be nice to show them here:
- Reroute the fuellines, out of the way from the hot manifold. I've used a piece of the inletline from a scrapped Y to make a longer exitline that runs towards and along the radiatorstay, hopefully cooled by air flowing through the bonnetslats.

- Add a phenolic spacer. The one I had (from a Mini?) was too thick so I sawed that in half.

- Fit a (prototype?) heatshield.

- Add a phenolic spacer. The one I had (from a Mini?) was too thick so I sawed that in half.

Willem vd Veer

and another picture

Willem vd Veer

and another

Willem vd Veer

and the last one

Willem vd Veer

Hi Willem

Sorry to hear you missed the Sommertreff - hopefully Karl or Manfred will file a report to tell us all about it and whet the appetite for Sommertreff 2011.

The Heat shield and insulation block you describe above is actually very comprehensively covered in the MG Car Club Y Type Register Datasheet 1 which can be obtained from Mike Silk. Sadly the MGCC Y Register decided to remove their shop from the www.mgytypes.org site, but I believe Mike is still able to supply this and other items.

Great photos though and I like the rerouting of the fuel line!

Paul
Paul Barrow

A credit to you Willem. I moved my pump to the left hand side of the battery box [the cool side] many years ago after a vapour lock one hot day on a C de Brouis mountain pass near Sospel France. The quick fix was to spray cold water over the pump and prop the right hand bonnet side panel open, cool air then circulated around the pump so that the next pass down to Nice went without trouble. It is a bit non-original but so is modern fuels and traffic density. Bryan
B Mellem

Hello Willem. I had a vapor lock problem in my TD when I drove up to independence pass in Colorado (12100 ft). I made an adapter that screws onto the gas tank and the gas line screws onto the adapter (I don't like to cut things). See the attached image. It has outlet and inlet hose barbs so I can go out to an electronic pump that I mounted at the rear. I also did this to my Y. I haven't had a vapor lock problem since. I've driven the car across the desert in 115 F temps several times. (that wasn't a lot of fun)

Butch Taras
VMG

R Taras

Willem:
What you have done looks very good, and I hope it brings some relief from the vapour locking.

One thing I did during the rebuild of my car was to re-route the fuel pipe from the tank to run behind the battery box to the pump, which is still in its original place.

This avoids the pre-heating effect from running the pipe past the hot cylinder head.
I'll post a pic or two when I've taken them!

I find that the car will run fine in hot weather without a shield - provided you don't switch off! At that point heat soak from the manifold makes restarting quite difficult.

I've never driven at the altitudes Butch describes - though I've been up to about 1000m/3300ft with no apparent ill effects.
Tim Griggs

Willem

This looks very professional. Any chance of a drawing, or dimensioned sketch of the heat shield. I am suffering from the vapour lock problem and intend to fit a heat shield this winter.

Mike
M Long

Mike,

Thanks for the compliment. As a matter of fact I've only had vapourlock after a very steep run in the Swiss Alps in hot weather, but with the modern fuels chanching rapidly, I don't think it will do any harm.

I just took a littering sheet of aluminum and that dictated most of the shape (height) including the "strenghtening ridge".
I traced a gasket on it to position the holes and drilled/sawed them out. After that I modelled the left side roughly to follow the carburettor foot. So no drawings as it is so simple to do it freehand.

This shield is only a prototype and I think it should be bigger, shielding a bit more of the bottom of the floatbowl.

As Paul said:
The Heat shield and insulation block is actually very comprehensively covered in the MG Car Club Y Type Register Datasheet 1 which can be obtained from Mike Silk. Sadly the MGCC Y Register decided to remove their shop from the www.mgytypes.org site, but I believe Mike is still able to supply this and other items.
Willem vd Veer

I had repeated vapour lock problems (including once, on hot day, when the bride had to get out and help push the car off the road!). I overcame this by taping some split insulation foam tubing (used by plumbers for hot water pipes) to the flexible hose from the pump to the carb. Looks rather ugly but effective and still on there!
Barry Bahnisch

A small bottle of water, an empty liquid soap container will do, when sprayed over the pump fuel chamber and feed pipe will condense the vapour straight away. The bottle can be used also to spray the windscreen from the drivers seat if washers are not fitted. It will at least get you home.
B Mellem

This thread was discussed between 18/08/2010 and 27/08/2010

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