I think that thing is going to look pretty good under the hood.



Yellow 292 with black accys and ceramic coated rams horns.

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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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This post was created using OpenSuSE Linux x64 and Firefox

I think that the 600 cfm 4 barrel set-up suggested by Pete is right on - mine had #58 primaries in it and I was working my way down (312 motor). When that front barrel is wide open (the mechanical primary) the fuel flow is the sum of the metering jets and the 6.5 power valve. Modifying the power valve flow orfice (in the metering block) is the arena of the real carb pros - leave it alone.

Pete didn't mention which of the vacuum secondary springs he's got in there but....get a stiff one - the 292 won't need the extra capacity at quite the same engine speed as your old 460. I usually just put the Holley heavy black spring in there and worry about opening the thing quicker somewhere off in the future.

The four barrel will look better on your toy anyway!.......

 
 Steve Metzger       Tucson, Arizona

I guess I have to agree with that. (now that I think about it, why would any engine run significantly richer or leaner than any other engine)



The carb wouldn't really "know" what's bolted up under it it only knows airflow thru it....



The primary venturi size appears about the same as the 2bbl Holley I have that came off the 239 I removed from the truck.



The other different thing about it is that it is a "marine" carb. I don't know why that would be a problem though...

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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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This post was created using OpenSuSE Linux x64 and Firefox

This discussion brings up an interesting point:



Before exhaust analyzers/floor dynos/drag strip timing were commonly available, people would choose jet sizes by reading the plugs. Yet, proper plug heat-range selection is likely dependent on a correctly jetted carb setup. It's the old "chicken or egg/catch 22" story.

6 VOLTS/POS. GRD. NW INDIANA

HT,

      NO!  The carb doesn't care what size the engine is. It only reads airflow. As Ted mentions there's a lot of factors that affect the mixture, but the jetting is based strictly on airflow through the venturii, period.

                                           Frank

Frank/Rebop

Bristol, In ( by Elkhart) 

Like Frank mentions, baseline jetting should be the stock jets for that particular carb.  Using the jet sizes for the stock 1957 List #1273 Holley carb as a baseline for anything other than this simply doesn’t work.  As an example, there are a multitude of different list number 600 cfm Holleys out there and most have different baseline jetting requirements.  The air bleed sizes dictate this to a large degree and because of this, baseline jetting for each will vary.

 

And as Gary brings up, a smaller sized carb will have a higher velocity which in turn promotes improved atomization of the fuel (smaller droplets) which in turn will burn more of the fuel.  A carburetor that’s larger will have a slower velocity which will have weaker signal in which to draw fuel through its circuitry and also atomize the fuel at the venturi.  As a rule of thumb, increased velocity equates to increased torque.

 

Jet sizing is more related to the venturi size and the associated air bleeds within the carburetor and not the size of the engine for which the carb is being installed on.  The vacuum signal as well as the exhaust flow of the engine on which the carb is being installed on my dictate a given amount of jet change from baseline but there is no rule of thumb saying bigger or smaller jets when switching the same carb on a different sized engine.  If a carb is specifically designed for a small cubic inch engine and is then re-installed on a much larger one, then the potential for it running rich at idle is high due to the fuel transition slot being more exposed.  The first thought is to put in smaller jets but this simply puts the engine in a lean condition at the higher rpms.  Likewise, taking a carb designed for a large cubic inche engine and reinstalling on a small one will have the transition slots not exposed enough and creates a situation where a dead spot off of idle exists.  In both of these cases, more most be done to the carbs than a simple jet change to address the different issues.

Lorena, Texas (South of Waco)

Frank,



I'm guessing that jets that size might be correct for a 460 but wouldn't they be rich for a much smaller displacement engine?



I suppose I could pick up a couple of smaller sets so I can try them. I may just give Holley a call and ask them if they have a suggested starting point. At this point I just want it to run good. It's definitely NOT going to be a hotrod!






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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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This post was created using OpenSuSE Linux x64 and Firefox

HT,

      Look at the FRONT of the carburettor. The choke tower is the area at the top that the choke plate is mounted in. The front of the tower is the higher side, on the diver's side front you should find numbers stamped, they may be a Ford number or a Holley number, but either way that's your list number.

      The 731's are close tolerance 73's and that does sound big. HOWEVER, the factory jetting is established on a flow bench and by testing, they know what they're doing. I would NOT deviate more than 3 or 4 sizes either way without wondering what else is wrong. As far as the secondary plate goes, they're easy to change, but don't mess with it until you see what you have ON THE ENGINE. Don't guess. 

Frank/Rebop

Bristol, In ( by Elkhart) 

Well,





Of course, I want to be happy too!



I do have a Holley 2bbl and a Ford 2 bbl carb. I'll look them over and see where I should go. My 2bbl manifold has a cracked bolt hole in the front. I may have to try to weld it I guess. Now is the time to try out some of that nickel TIG rod I've been wanting to try I guess...



I'm sure I can sell this carb. It's in pretty good shape. and it IS a marine carb. They're usually in demand.....(well maybe back when people could afford to operate boats....)



















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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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This post was created using OpenSuSE Linux x64 and Firefox

The reason for suggesting a smaller carb (400 cfm),  The cleaner the engine burns the fuel the better the gas mileage, the quicker the response thus more lowend POWER. I had a beautiful new 770 avenger holley to put on my t-bird ( 312 strocker ), it was too large so I sold it to my brother for his 428 cu in ford engine and now I have a 670 avenger on it and as it performs better than the 770, I am much happier.

-Gary Burnette-