Roger Barrett Posted December 18, 2014 Share Posted December 18, 2014 We are building a Marvel carb for a 35 series 50. Last of the marvel carbs, the acme of their development. Even has port for vacuum advance. That being said, it is the same technology Buick used for maybe 20 years prior. To set the float level, I need to know the fuel pressure the mechanical fuel pump supplies. On earlier carbs I use a gravity flow setup to supply the carb and tweak the float to put the fuel level just below the end of the high speed nozzle. On this one, I need to have the correct pressure supplied. I am guessing between 3-7 PSI. I have the shop manual and it shows every specification but that one. Any ideas?Regards, Erik and Roger, Rumble Seat Garage. Link to comment Share on other sites More sharing options...
Mark Shaw Posted December 18, 2014 Share Posted December 18, 2014 3-4 psi at the carb. is plenty. Link to comment Share on other sites More sharing options...
carbking Posted December 19, 2014 Share Posted December 19, 2014 3-4 psi at the carb. is plenty.X2. AC specified 3~4 psi for this pump.Jon. Link to comment Share on other sites More sharing options...
Roger Barrett Posted December 19, 2014 Author Share Posted December 19, 2014 Thanks, guys. I will set the float level at 4 psi. My research indicated the same. This carb has been a project. I had to spray weld a new ear on the air valve housing that was broken off and also replace the tubes in the heat riser housing. Thanks to Bob's Automobilia for making the kit available with tne Nitrophyl float. Erik and Roger Link to comment Share on other sites More sharing options...
Larry Schramm Posted December 20, 2014 Share Posted December 20, 2014 Roger,The fuel pressure is 3-4 PSI at the fuel line going to the carb. This is a function of the fuel pump. You can check the pressure at the carb by "Teeing" in a fuel pressure gauge to the line that feeds the carb. The float does not set fuel pressure. Link to comment Share on other sites More sharing options...
Marty Roth Posted December 20, 2014 Share Posted December 20, 2014 Roger,Mark and Larry are correct, specifying 3-4 pounds. I added an in-line 6-Volt electric pump, primarily to prime the system after long rest, and in case of vapor lock with corn gas. To be safe, I also added a fuel filter before the electric pump, and a fuel pressure regulator after the pump.As you probably know, the 1934 and 1935 Buicks are essentially identical. Link to comment Share on other sites More sharing options...
Roger Barrett Posted December 20, 2014 Author Share Posted December 20, 2014 Larry, understood that fuel pressure is not set by the float, but fuel level in the bowl is affected by fuel pressure. So I am using an electric pump with adjustable regulator and pressure gauge on my test bench to adjust the float. For many years I had a 17 D34. That car was real performer, would run away from the model T's and Dodges of the period. Marty, that's a fine looking machine. I don't know what model this carb is going on, but I think all the 34/35 Buicks are beautiful cars. Wise to have an electric pump for the reasons you stated. All of mine do.Regardss, Erik Link to comment Share on other sites More sharing options...
Marty Roth Posted December 21, 2014 Share Posted December 21, 2014 Marty, that's a fine looking machine. I don't know what model this carb is going on, but I think all the 34/35 Buicks are beautiful cars. Wise to have an electric pump for the reasons you stated. All of mine do.Regardss, ErikErik and Roger,Thank you for your kind comments per my 1934 50 Series Buick.Your first post in this thread stated: "We are building a Marvel carb for a 35 series 50. Last of the marvel carbs, the acme of their development. Even has port for vacuum advance."Your most recent post says: "I don't know what model this carb is going on,".Has something changed, or isn't this going back on the 50 Series 1935 Buick? I would certainly enjoy seeing the finished project. By the way, mine may become available, but only for a ridiculous price. Link to comment Share on other sites More sharing options...
Roger Barrett Posted December 21, 2014 Author Share Posted December 21, 2014 I have not seen the car, all I know is it is a 50 series machine. The job was referred to me by Bob's Automobilia. The car is in Vallejo, Ca. I will get more info and pics if I can.Regards, Erik Link to comment Share on other sites More sharing options...
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