Broken vacuum tube from distributor to carburator

[johnjmurray]

I noticed on my 1950 Pontiac that the copper tube that runs from my distributor to the carburator is broken and has been for a while, I think. From reading the manual this tubing applies pressure from the manifold to the distributor for "spark advance". My question is if the tube is broken how is this affecting the engine performance? How detrimental is this to the engine?

Granted, I plan to fix it soon, I am curious what if any longer term damage it may have caused.

Thanks,
John Murray

[Larry]

The vacuum tube being broken will not cause any damage. It is a small ID and I would suspect it isn't broken completely open in two, so probably more split or cracked. Regardless, it won't damage anything.

However, it will make the fuel leaner, a bit rough at idle, and perhaps the engine starve a bit. Plus, you won't get any vacuum advance during acceleration, so the performance will be less peppy.

You can fix it very simply with a short piece of rubber tubing spanning the broken area. You might want to be sure the broken ends are clean and not crimped closed at all. No need to replace the entire line. Don't forget a couple clamps too.

[johnjmurray]

Larry - this tube is definitely broke in half, I will replace the tubing and clamp it as you suggested. It appears that was a fix years ago but that rubber tubing decided it was too tired to hold on any longer.