Vaccuum thing on a B manifold??

Fresh air inlet for better hot starting?

My dad said some tractors could run various things like cow milking equipment by using the engine vacuum.

Dick L wrote: R W, Could you tell me how that works to open it to help start a tractor?

Edited by R.W - 07 Nov 2011 at 7:06pm

Dicks got it right. I milked many a cow one unit at a time off our WD and also off our 1960 GMC pickup that had a V6. But our petcocks had a longer nipple to hook the cacuum hose to. So maybe this one was cut off or indeed used for something else as suggested.

We had a C that had the petcock on its manifold.  I remember using it a couple of times for milking when the power was out.  You need to tie the hose to your main vacuum system in order to have a reservoir. This was eons ago when a larger farm back in Wisconsin consisted of 50 cows.

I HAD A 60 COMBINE WITH ONE OF THEM ON IT & IF YOU KILLED IT WHEN HOT, JUST OPEN THE PETCOCK & IT WOULD FIRE RIGHT UP. IF YOU DIDN'T OPEN IT YOU COULD CRANK & CRANK. IT WOULD FLOOD IF NOT OPEN.

I have one FS if anyone needs one.

We ran a WC for many years on a reuse pit well, and we had a valve similar to that one installed in the manifold, and use the manifold vaccumm to prime the suction line.  Start the tractor, open the valves, watch the sight glass, which had a float valve in it to block water from going to the engine, and (it's been a loong time, so it may have taken longer, or not as much) but in about 5 minutes your pump was primed, close the vaccumm, and engage the PTO.  The total length of suction line was around 20 feet, and the diameter was 6", so we aren't talking 500CFM flowing bypassing the carb, but maybe more like .785cfm if I did my math right.  That will not flow enough air to lean the mixture much at all.

I had a guy come once to pump our septic tank. He had a sealed tank on his truck and used the truck engine to supply vacuum to the tank.

TimNearFortWorth wrote: Yup, you can milk with it as we used to run a single Surge milking machine on one when the power would be lost in an ice storm. My dad has told of opening the barn doors for fresh air and running three WD-45's staggered down the barn floor for milking on their large dairy during upstate NY ice storms in the late 50's.

How do you hook it up? All the ones I have seen used for milking, had a hose barb sticking out. This one isn't cut off, it was made that way.

Let's clear up some confussion.  I think that the one in the picture, is designed for and made to clear a hot flooded engine, and what the rest of us are talking about is that with the right valve, i.e. something with a nipple or other fitting, you can use the manifold vaccumm for other things.  I don't think that any of us are stating that that specific valve is only used for vaccumm work.  I think some of those posting took the question very literal, as they should, i.e. that specific valve, some of us, myself included, thought the question was more a theory question.  My mistake.

Edited by Orange Blood - 08 Nov 2011 at 9:27am

I have WW2 vintage generator and it has such a petcock on the intake manifold. Its hand crank start with a 10 hp 4 cylinder Herculese engine on a 3 KW generator. There it was used to prime the engine when choking and hand cranking didn't work in cold weather.

Gerald J.

We had a hand-crank B that we used the petcock to get it started when hot.  Worked like a charm.  Kind of an anti-choke.

I've seen a hercules that had a bellows type throttle with a petcock to adjust RPM. It used that hole in the manifold for vaccuum and it also acted like a govenor and it recovered pretty good from a load. It was on a welder

Heres one on a tractor my grandpa used to have....