Lou Earle Posted February 2, 2009 Report Share Posted February 2, 2009 Been looking over things about carbs lately and just curious- Has anyone ever fitted the 230 or 218 with a 4 barrel? I have a 4 brl manifold for a pinto 4 cyl for a 53 Ford v/8 but I have not heard or seen anything about a 4 brl for our cars- wonder why?? seems to be 4 barl would be good . Lou Quote Link to comment Share on other sites More sharing options...
Normspeed Posted February 2, 2009 Report Share Posted February 2, 2009 The progressive opening would be good for gas mileage. Guess you'd need a pretty small 4 barrel to work well with our small displacement motors. Quote Link to comment Share on other sites More sharing options...
greg g Posted February 2, 2009 Report Share Posted February 2, 2009 Some one suggested on here that the flow rate on these things might max out at around 375 to 400 cfm. Most 4bbls are rated for more than that. I looked around for quite a while before I found the 550 for use on my 259 Studebaker (some have said it might be to big) any way the only thing smaller that not so commonly available are Carter WCFB's that were used for early dual 4bbl set ups. I believe these are 400 0r 450's, but because they were used for early performance cars like Corvettes with the powerpack 283, they are even as cores very expensive and difficult to find. That said there are a few folks running 2 2bbls which probably have moe flow potential without any problems. Like to see some one with access to a flow bench test these combinations and post the results. Quote Link to comment Share on other sites More sharing options...
woodscavenger Posted February 2, 2009 Report Share Posted February 2, 2009 So who has info on 2bbl conversions ir the 4bbl is not applicable? Quote Link to comment Share on other sites More sharing options...
Bodacious Posted February 2, 2009 Report Share Posted February 2, 2009 Holley makes a 390 cfm four barrel, at least they used to so I would think they still do. It was a spec carb for some racing classes. Also it was frequently used in smaller displacement dual quad applications, particularly on the street. Quote Link to comment Share on other sites More sharing options...
Bodacious Posted February 2, 2009 Report Share Posted February 2, 2009 Yep, they still make it. http://www.holley.com/0-8007.asp http://www.jegs.com/i/Holley/510/0-8007/10002/-1 Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted February 2, 2009 Report Share Posted February 2, 2009 I have a set of sketches for a 390 Holley 4-BBL for my 251 flathead. I just have not had time to get my welder to build it. The BIG issue is the air-bleeds. They are WAY to large for these engines and you will never get the idle correct. Now there is a Holley housing that has ADJUSTABLE air bleeds. it is not the standard carb but is still available. If one is to build a 4-bbl set up, you will need this housing so that you can adjust the idle air bleed for the small engine. Also, if you calculate the CFM for one of these cars, the VE (volumetric Efficiency) is very low around 65%. Don't forget to take that into consideration and reduce the CFM by the VE amount. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted February 2, 2009 Report Share Posted February 2, 2009 This carb calculator has to high a VE for our engines and provides a result that is too high. Do it long hand: Carburetor CFM = Engine CID X Max RPM /3456 (***The above formula ONLY applies to a 4-bbl carb. The calculator on the link you provide probably only works for a 4-bbl as the formula is different for a 4-bbl, or a 2-bbl or a 1-bbl. due to the pressure differential issues.) Then reduce it by the VE. For our engines with a stock cam, no porting, stock exhaust use 65%. If a hot cam, ported, and good headers use 70%. I did the math for a 4-BBL and here it is: CID: 251 MAXrpm: 3500 VE in %: 0.7 Constant: 3456 EngineCFM required: 178 Best, James Quote Link to comment Share on other sites More sharing options...
greg g Posted February 2, 2009 Report Share Posted February 2, 2009 Well didn't someone post that the 1bbl B and B flows 250/270 which was pretty close to the carter webber 2bb? Finding a 180 cfm flow 4bbl might be a bit hard. Quote Link to comment Share on other sites More sharing options...
James_Douglas Posted February 3, 2009 Report Share Posted February 3, 2009 Greg, I am not saying one should go looking for a 178 CFM carburetor. I am saying that 178 CFM is in fact what a 251 Ci. In. flathead engine at 3500 RPM with a VE of about 70% requires. Anything more carburetor wise is a waste as the engine cannot use it. Also, if the venturi size gets too large (more CFM) then the pressure across the venturi will drop and it will not flow (pull out) a "proper" amount of gas especially at idle. Most cars have been way over carburated. That is why when guys put a fuel injection setup on an old car they tend to get better mileage all other things being equal. An interesting technical note is that the 1BBL Carter in my Desoto has a main metering jet that flows 314CC a minute. So the most gas it can use is about 5 gallons an hour. This is about right as at about 2300 RPM on the highway at 50 MPH I use about 3 gallons an hour. In the event that anyone want to know what a carter jet flows, I have a book with the part number to CC table. Best. James Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 3, 2009 Report Share Posted February 3, 2009 I have seen 4bbl setups on Hudson flatheads but I have never seen one on a Mopar flathead. Quote Link to comment Share on other sites More sharing options...
greg g Posted February 3, 2009 Report Share Posted February 3, 2009 Just remembered, that I had a Mazda rotary engineded car back in the 70's. These were equiped with a 375 to 400 cfm 4bbl, so if you have a yard around you might look for Mazda Rx3 Rx4, Cosmo, or Rx7's as donors for smaller carbs. Might even be possibl to machine a stock manifolt to accomodate it. I believe they were Keihnin or Mikuni. Racing beat is a company that deals in aftermarket stuff for Mazda and they sell a 475 CFM holley for performance aplications for those engines. One would probably want to look for a 13B series engine as they were more diaplacement than the smaller 12A. They would be found in the Rx4 and later Rx7. Also be onthe Rotary pickup if any are still around. I had an Rx4 and in the 6 years that I owned, I never touched the carb, so they were a reliable deal. Vacuum secondaries that opened at 4000. which on the rotary was about half way through the rev range. factory red line was 9K but they would easily rev to 10 plus. Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted February 3, 2009 Report Share Posted February 3, 2009 I have seen 4bbl setups on Hudson flatheads but I have never seen one on a Mopar flathead. Don, does that Hudson run on the "White Lightning" sittin' on the head? Quote Link to comment Share on other sites More sharing options...
Don Coatney Posted February 3, 2009 Report Share Posted February 3, 2009 The Hudson owner is my good friend Mark Hudson (AKA Hudsonator on a few other forums) who does live in a very remote area of the Tennessee hills. Quote Link to comment Share on other sites More sharing options...
woodscavenger Posted February 3, 2009 Report Share Posted February 3, 2009 In other words.....yes, it's white lightning. Why do you think they are building a hopped up flattie. They have to outrun the local constabulary! Quote Link to comment Share on other sites More sharing options...
Flatie46 Posted February 4, 2009 Report Share Posted February 4, 2009 I was thinkin the hudson flat 6 was 308 ci, so it could probably run a 4 barrel without losing intake velocity. Quote Link to comment Share on other sites More sharing options...
tinlizzy Posted February 4, 2009 Report Share Posted February 4, 2009 Hummm would a 308 Hudson flattie fit a 48 dodge pickup? Just wondering. That would sure be out of the ordinary. I have one of those jars too. Lee Quote Link to comment Share on other sites More sharing options...
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