Any problem with installing a dual action (vacuum) accessory fuel pump from a 42-51 engine on my 39 216? I'd like to have more reliable windshield wipers.

Thanks!

No problem.Its even shown as an accessory in the 1938 accessory book....the 1937-51 fuel pumps are all the same.....you will need to run an extra set of lines.If your using an old stock pump and the edges of the diaphragms that stick out past the castings feel like sticky friction tape they are N.G.

The 49/54 shop manual gives a good description of the operation of the pump as well as information on the proper plumbing.

Quick question - I see some fuel pumps with the vacuum acessory listed as single action and others listed as dual action. What's the difference. A single action should be good enough to make my wipers work better, right?

A single action pump is just a fuel pump-gas only-as what you presently have.The dual action is a fuel pump plus the vacuum pump for the wipers.

The reason I was asking is because I can get a NOS A/C #9803 (Chevy part # 5592626). The parts book lists this pump as a single action. That's what got me a bit confused.

http://chevy.tocmp.com/1929_54chevyparts/03/214.HTM

I see in the parts book what you are refering to.A change was made to the fuel/vacuum pump in mid 1952...to quote Chevrolet" A new combination fuel and vacuum pump was introduced in mid 1952 as a regular production option for all models.Although the fuel side is the same as formerly used.there are important improvements to the vacuum side.The fuel and vacuum pump has been redesigned during 1952 for improved wiper operation.An extra set of valves is incorperated to provide vacuum pumping from both sides of the diphragm.This double acting design supplies a more dependable wiper operation during adverse driving conditions"....Was used only in the pump for 1952 and up which had the inlet and out let fittings at an angle due to the new motor mount bracket.Could be used on prior years by bending the gas line.

The diphragm in a pump that old could be bad due to old age--if its sticky feeling as I mentioned it NG-if its a later unit t it will feel like good rubber.