Re: vacume tank or vapor lock 1929 626

Posted by DavidM On 2012/9/2 7:01:00

29tons, in response to your question about the vent, the owner of the twin six had drilled a hole in the top plate of the carburettor float bowl, soldered a standpipe that was routed up a short distance, discharging below the engine. It was not very tidy but the car was a driver not a show car.
The twin sixes have the carburettor mounted in the "V" between the cylinders with the exhaust manifolds running closely along each side making a heat shield a virtual necessity for any significant driving and although our 1929 cars are not as bad I believe that the heat shield is the first line of defence. It can be done neatly but would not suit a show car.
Another method I have used when touring in hot weather is to make spacers that lift each side of the hood a few inches so that air is directed into the engine bay over the top of the radiator instead of being heated passing through the radiator.
This does not look good when driving but in hot weather some drastic measures are needed.
I have driven my 633 in 100 deg plus weather with lots of kerosene in the fuel, a heat shied, hoods raised and it still vapor locked when stopped at traffic lights.
I have now fitted an electric fuel pump that delivers fuel directly to the carburettor bypassing the vacuum tank. It is only for use when needed, I have not yet had the opportunity to test it when vapor locked.