wmsue Posted March 3, 2018 Share Posted March 3, 2018 Congrats. Glad you got it working. Keep driving !! Bill 1 Link to comment Share on other sites More sharing options...
zeke01 Posted March 4, 2018 Share Posted March 4, 2018 My vacuum tank Epiphany: I was on a VMCCA Nickel tour driving my 1928 Chrysler. I happened to be the last tour car when I got stopped at a railroad crossing on some quiet back road. As I sat waiting for the train to pass, the vacuum tank refueled causing the engine to stumble a bit. Here I was alone with a 60 year old car that wasn't running the best and no one around to help if the old beast died. What was I to do? About that time the train passed the crossing and the vacuum tank refilled causing the engine to smooth out.The crossing guard and lifted I thought to myself "Well, we have gotten this far, let's see if we can make it to the end of the tour. We did. Afterwords I did investigate the vacuum tank to find out exactly how it works and how to fix it. If you are going to own one of these old beasts you had better know how it operates and how to fix it. The "technicians" at the dealership aren't going to be a lot of help. Zeke 1 Link to comment Share on other sites More sharing options...
hchris Posted March 4, 2018 Share Posted March 4, 2018 Well done, your perseverance paid off and you have given others a unique insight into the black art of vacuum tanks. Now go find a big hill and see if you can make it to the top without running out of gas, if you can achieve that go home sit down and have a beer or two. ?? 1 Link to comment Share on other sites More sharing options...
frank29u Posted March 4, 2018 Share Posted March 4, 2018 Good for you. Link to comment Share on other sites More sharing options...
wayne sheldon Posted March 4, 2018 Share Posted March 4, 2018 We now must dub thee apprentice wizard master of the vacuum tank! Soon to be Master Wizard Master of the Vacuum Tank. 1 Link to comment Share on other sites More sharing options...
hchris Posted March 7, 2018 Share Posted March 7, 2018 On 03/03/2018 at 10:09 AM, seando said: I wonder what yellow is? It is a straight pin hole to the vac line from manifold. I have it capped off. All quiet here so I assume everything is fine, still scratching my head re the unidentified "yellow" port in an earlier thread and then I came across these items, courtesy of the Dodge Brothers newsletter some years back (a gold mine of information for Dodge owners). So its purpose in life is to increase the vacuum force (booster). This enables a greater pulling power for fuel from the rear tank and is particularly helpful for high throttle openings when going uphill etc. which reduces the risk of running out of fuel in the reservoir under such conditions. 1 Link to comment Share on other sites More sharing options...
imnuts4fords@comcast.net Posted March 7, 2018 Share Posted March 7, 2018 Years ago a club member asked my dad to help him set the idle jet on his car. Dad set the idle nice and slow and then all of a sudden the engine really slowed down almost dying and dad quickly adjusted the idle a little higher. With that we sat back and was happy with the idle speed of the engine. All of a sudden the engine sped up to a faster idle, so dad again adjusted the idle jet to slow it down. He then looked on the firewall and noticed the vacuum tank and realized when the tank needed refilling, it took some vacuum and slowed the idle. Yes, your engine will slow down when the vacuum tank is being filled. Similar to driving up hill in the rain with the wipers on and you have vacuum wipers. At this situation you may not have sufficient vacuum to run the wipers. You may have to let up on the throttle (and slow down) to get the wipers to work (or downshift) and then give it the gas to get up the hill. Understanding what is going on under the hood really helps. Don A Link to comment Share on other sites More sharing options...
frank29u Posted March 7, 2018 Share Posted March 7, 2018 hchris, thanks for the valuable information on that fitting. I wonder why the Chrysler engineers took the vacuum from the manifold instead of of the oil pump like they did on the 28/29 Plymouth? May be different oiling system on the 6 cylinder vs 4. Never want for vacuum/gas going up steep hills with this Plymouth setup. The wiper, on the other hand, comes from the manifold and it can be sluggish, as we all know. Link to comment Share on other sites More sharing options...
hchris Posted March 7, 2018 Share Posted March 7, 2018 Well it seems the move to change vacuum source from manifold to oil pump came fairly late in the evolution of vac units, so I can only guess this was a means of overcoming loss of vacuum with large throttle opening. It wasn't much later that mechanical fuel pumps became the norm and the problem disappeared. Link to comment Share on other sites More sharing options...
frank29u Posted March 7, 2018 Share Posted March 7, 2018 For Plymouth, the Finer 30U was fitted with an AC Fuel Pump-Series B after car s/n 151757, according to United Motors Service parts book for Plymouth 1928-1934 models. Link to comment Share on other sites More sharing options...
hchris Posted March 8, 2018 Share Posted March 8, 2018 Yes the vacuum force is all about throttle position, the more you open the throttle the less vacuum you have, so there is a contradiction here in engine efficiency with these systems, the amount of fuel you have stored in the vac tank gets less and less the wider you open the throttle. Giving it more gas to get up the hill will only make matters worse. Link to comment Share on other sites More sharing options...
old car fan Posted March 8, 2018 Share Posted March 8, 2018 Did dodge and Desoto switch in 28 /29,my book somewhat shows it Link to comment Share on other sites More sharing options...
Spinneyhill Posted March 10, 2018 Share Posted March 10, 2018 (edited) On 9/03/2018 at 10:59 AM, old car fan said: Did dodge and Desoto switch in 28 /29,my book somewhat shows it If you mean when did they switch to mechanical pumps... Dodge 1930: DC, DD, DE, DF first with AC fuel pump. De Soto 1930: CF, CK. If you mean switching brands of vacuum tank, Dodge 130, 131, 140, 141. 2252, DB, Domestic DA and some export used Kingston tanks. Models before these used Stewart Warner and some export DA had SW tanks. Some 130, 131 and 2252 also used SW tanks for foreign orders. Edited March 10, 2018 by Spinneyhill (see edit history) Link to comment Share on other sites More sharing options...
seando Posted March 14, 2018 Author Share Posted March 14, 2018 Amazing info @Chris. Thanks. Have been out of town. Sounds like it was designed to run uncapped? I can't seem to imagine how that works. I guess something changes as your going up the hill. Link to comment Share on other sites More sharing options...
hchris Posted March 15, 2018 Share Posted March 15, 2018 3 hours ago, seando said: I can't seem to imagine how that works. I guess something changes as your going up the hill. The fitting has an inbuilt venturi fed by the hole which you have blanked off. The venturi is designed to create an even bigger (atmospheric) pressure drop for the vacuum source at the top of the inner tank, which in turn will lessen the effect of manifold vacuum drop as you open the throttle; particularly helpful if you have a long uphill drag. Of course this is really only beneficial when you have a inlet manifold source of vacuum, its therefore unnecessary with an oil pump vacuum source which increases vacuum with oil pump (engine) rpm. Link to comment Share on other sites More sharing options...
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