Clymeric Posted January 18, 2016 Report Share Posted January 18, 2016 Bought a 51 Plymouth Cambridge with a good running 218 flathead a few months ago... I'm not a master mechanic, am using this project to learn. Seems one of the best ways to get a mild hp boost is to up the exhaust, so I picked up headers from Tom Langdon and a couple of glasspacks mufflers. I will eventually swap the intake manifold & add a second carb, but don't have the cash yet. So my question... what is the device that sits above the central portion of the headers and is connected to the carb via linkage (see attached photo)? I'm guessing it's some kind of heat riser .... can it be removed during header swap without any mechanical repercussions? Many thanks for any help - I know I'm a novice, that's why I'm asking "stupid questions" here before I tinker with this beauty. Quote Link to comment Share on other sites More sharing options...
knuckleharley Posted January 18, 2016 Report Share Posted January 18, 2016 It's a choke pull-off device. Once the engine warms up it pulls the choke open. 1 Quote Link to comment Share on other sites More sharing options...
Andydodge Posted January 18, 2016 Report Share Posted January 18, 2016 Kunckles right, that's the auto choke, re your question tho, check the "cracked exhaust manifold" thread and my answer....I'd wait till you got the coin for the intake and extra carby......I was thinking that I may get away without the heat riser as where I live its not really cold however the use of some sort of intake manifold heat would more than likely be needed..........andyd 1 Quote Link to comment Share on other sites More sharing options...
desoto1939 Posted January 18, 2016 Report Share Posted January 18, 2016 You have what is called a sisson automatic choke. These are actuated via a wire that runs from the starter to the choke. This is a bimetal plate onthe base of the choke body that is near the top of the manifold. As the manifold gets warmer then the bimetal plate then warmer up and then the choke start to open and lets more of the choke release. This also is not a heat riser that is the box section that in under the upper and lower manifold pieces and has a big counter weight on the outside of the manifold. Contact me for more information. Rich HArtung Desoto1939@aol.com 1 Quote Link to comment Share on other sites More sharing options...
Clymeric Posted January 21, 2016 Author Report Share Posted January 21, 2016 Thanks for all of the input, guys! I'm thinking I can get by without a choke, you just have to warm it up properly in cold weather, right? I live in Charlotte, so that is only a problem for 2-3 months... and I'm itching to get those headers installed. Quote Link to comment Share on other sites More sharing options...
blucarsdn Posted January 21, 2016 Report Share Posted January 21, 2016 You are going to find out that the addition of headers to a stock engine does nothing but add noise which some people equate to added power,, wrong!! If you live in an area that has cold winter weather, ie: NC would qualify a heat riser is a must, the engine will run cold and thereby the fuel will not vaporize properly causing the engine to run rich. If you are dead set on putting the headers on, save your money until you can afford a dual carb/4 barrel intake with a heat riser built into it.. Clifford, 6=8, makes an excellent 4 barrel intake for inline engines.. The good aftermarket intakes have hot water heat risers built into their manifolds.. Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted January 21, 2016 Report Share Posted January 21, 2016 (edited) Can you post a link to the 4 bbl intake for our cars ? All I found were intakes for the slant 6. Edited January 21, 2016 by Reg Evans Quote Link to comment Share on other sites More sharing options...
Frank Elder Posted January 21, 2016 Report Share Posted January 21, 2016 Maybe a 390 cfm holley 4bbl.......I would try a 2bbl first, 4 seems like bog city to me. Quote Link to comment Share on other sites More sharing options...
55 Fargo Posted January 22, 2016 Report Share Posted January 22, 2016 With "Siamesed" intake ports, do not know of how a 4bbl carb could be of any benefit at all on these engines. Even if it were custom made by someone, with steel tube pipe, the 2 middle cyls would get blasted with fuel, and the outer cyls would run leaner. The / 6, and a Hudson flathead 6, have 6 intake ports, so 6 runners can be utilized to balance atomized fuel from a central mount. On our engines, this is simply not the case, and running 3 carbs would make much more sense than a 4 bbl or even 1 2bbl ever would. I have pondered a single 2bbl set-up, but again, this will not culminate with a balanced mixture of fuel, to all cylinders, again not being very efficient, and most likely would end up with less torque/hp gains and fuel efficiency and end economy too. There are those who will state a dual or tri-carb intake for our engines is just eye candy, or the Kool factor, do not see this as the case at all, but again I am no expert. Please can we have some experts chime in......LOL Quote Link to comment Share on other sites More sharing options...
55 Fargo Posted January 23, 2016 Report Share Posted January 23, 2016 Was pondering a custom made intake, with 3 runners from a central mount for a small 4 bbl carb with small primaries and larger secondary's ( Quadrajet) comes to mind. Now you Guys who want to run 1 larger carb over multi carbs, this might be an idea. I have my doubts about it, but if anyone has made or done just this, perhaps you can chime in to answer those who may be interested.... Quote Link to comment Share on other sites More sharing options...
Robert Horne Posted January 23, 2016 Report Share Posted January 23, 2016 Thanks for all of the input, guys! I'm thinking I can get by without a choke, you just have to warm it up properly in cold weather, right? I live in Charlotte, so that is only a problem for 2-3 months... and I'm itching to get those headers installed. I live not far from you, in Virginia. I have not used a choke on my Coupe for the past 29 years, with no problems. Before I installed an electric fuel pump years ago, I would spray a little gas is the carb to prime the engine, if the engine had not been started for some time. With the electric fuel pump, I turn the key on and wait a few seconds before starting the car. Quote Link to comment Share on other sites More sharing options...
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