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By napaunderground - Last Year
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Ok team... I have to select a 4bbl carb for my 292.
I have a number of vintage takeoff holley/motorcraft/autolite units that have been in storage for 30+ years to choose from. My initial plan is to rebuild one and keep as many vintage parts as possible on my build.
I think a 600cfm would be sufficient based on my limited knowledge in volumetric efficiency etc...
Any opinions as to jet size for the initial startup and break in? Or strong opinions of a better carb option?
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By miker - Last Year
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Just to get started, here the link to Ted’s dyno test on single 4 barrels. Great reading and it will give you a start to look at your existing inventory.
https://www.eatonbalancing.com/2012/09/25/four-barrel-carburetor-testing-on-the-y/
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By Deyomatic - Last Year
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That's a great link...and now I realize I made a bad choice!
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By Ted - Last Year
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My two cents worth.
Always start off with the original jetting when installing a carburetor. Once the engine is running and has some actual driving on it, then the jetting can be evaluated as to whether it needs to be made slightly leaner or richer to get the fuel mixture spot on. If making more than a six number change in jetting, look for something else other than the jetting being the problem.
There are instances where the air bleeds are changed rather than the jetting as you may only be working on one end of the rpm range and not all of it. Likewise, changing the rate at which the power valve opens is an option to changing the jetting. An incorrect ignition timing curve can make for instances where it would appear to be a fuel mixture issue so watch out for that.
As an additional foot note, if a carburetor is grossly undersized for an engine, you may find it being on the lean side in the higher rpm band. Likewise, if it’s too big, it may be on the rich side of where it needs to be. 750 cfm vacuum secondary carbs are a good fit for Ford Y’s that have had camshafts, larger valve heads, and/or head/intake manifold porting added. For daily drivers and with the normal upgrades in camshafts for an upgrade in power, then the 600-625 cfm range works for many applications.
Here are some links to previous threads giving more information on carb sizing.
http://forums.y-blocksforever.com/FindPost14659.aspx
http://forums.y-blocksforever.com/FindPost135357.aspx
http://forums.y-blocksforever.com/FindPost135561.aspx
http://forums.y-blocksforever.com/FindPost130447.aspx
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By napaunderground - Last Year
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My initial excitement at finding a stock 1273-1 (ECZ-AD) carb off a '57 T-bird has faded since reading the linked threads, and doing more of my own research.
Seems like the best bet would be a Summit 750 based on Ted's comments. I don't want to be undersized, and the comments suggest the OE carb probably is.
We have basically '57 T-bird parts cam, ECZ-B intake, with ported ECZ-C heads on this 292 with Mummert rams horn manifold.
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By slumlord444 - Last Year
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Not to disagree with Teds results but I’ve had good success with the T Bird carb on a stock 292. That’s not saying that a larger carb can’t produce more power.
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By 55blacktie - Last Year
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napaunderground, your engine, even with the mods, isn't going to make 300 hp. If you had ported G heads/Mummert aluminum heads, more compression, more cam, headers, and more displacement, the Summit 750 cfm carburetor would be a good idea. On your engine, I wouldn't consider anything bigger than 600 cfm. In fact, I think you would be happy with the Summit 500 cfm carburetor. A carburetor with smaller primaries will be more responsive off idle and at lower rpm and should return better mpg under normal driving conditions.
It would be helpful if you posted the specs for that "57 T-bird parts cam."
FYI: I bought Holley's 8007 390 cfm carburetor for my 55 Tbird to replace the original Holley 4000 "Teapot" carburetor because it wasn't compatible (as is) with the 57 distributor that had been installed before I inherited the car. However, I sold the unused carburetor and purchased a Holley Street Avenger 570 carburetor because Tim McMaster said that the 390 cfm carburetor would not be big enough. Keep in mind that street-ported "G" heads/w 1.94 & 1.54 valves will be going on my engine, block zero-decked and bored .050, heads milled .035, a Howard's cam/w 220 duration @ .050 and net lift of .485/w 1.6 rockers. , ported 57 intake manifold, and Sanderson headers. Ted guestimated that my engine will dyno at 270 hp. You can expect less with your combination.
FYI: the 465 cfm carburetor was among the best in Ted's carburetor comparison test.
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By DryLakesRacer - Last Year
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Napa….. buy or get a carb that will be compatible to your engine, to your driving style, and how you’re planning on using your car. There are great usable carbs from 400-650 cfm that are normally ignored because “bigger is always better”. A good running 300” engine will perform very satisfactory on a 500 cfm especially at the crack of the throttle. Small primary throttle bores along with smooth Venturi’s will give the needed air flow and annular discharge for fuel atomization is a big plus.
If you feel that 5500-6000 rpm will be needed and used every-time you drive your car a larger carb may be for you.
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By Tealy64 - Last Year
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What great timing for this post. We just managed to track down an ECZ-B intake and are now on the market for a carb to fit it. I like the idea of buying a new one from Summit (sounds like a 500cfm will be fine for us, as we've not done any major mods to the motor). Any particular setups that are preferred over others? We're still on stock distributor and manual choke for our 64 F100 with a 292.
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By DryLakesRacer - Last Year
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Tealy, Summit carbs have high rating with many Y block guys. Bolt on and run. Ted has shown the larger one makes a very good performer and very acceptable horsepower on modified engines. I personally like they have no lower base to body gasket to leak; an Edelbrock has this feature also. I also like they come with a fuel line. They also use Holley jets and other parts which are common.
Eventually I will put the the 500 cfm I bought along with the Blue Thunder intake on my stock 292 when I remove the dual quads I currently use.
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By FORD DEARBORN - Last Year
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Since napaunderground mentioned having a number of vintage Holleys and Motorcraft carburetors on hand, don't overlook them as a good candidate for this occasion. I recently purchased for someone else, a 600cfm Holley list 7154 from epay under $100. This particular Holley required the common 37-119 Holley kit. These 1970 vintage carbs are totally overlooked by the hot-rodders. This means a good core is likely to be found in unmolested condition. After just finishing the rebuild to it's stock, for now, specs, I bolted it on my mild 312 and it performed very well with excellent response driving around the immediate subdivision as there is too much salt on the main roads at this time of year. This is the 2nd such "emission" carb that produced very good results. The first one is what I've been running very successfully on my 312 for about 5 years now but that could be a subject for another thread. If you don't mind spending the time to resurrect one of these carbs from the dead, it can be very rewarding.
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By napaunderground - Last Year
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@55blacktie I agree that I'm not going to be making big power here. Just don't want to put on a restrictor by selecting too small, and don't want to get crazy with too much. Appreciate the thoughts and provided information. I will update with the cam specs when I can get back over to the shop.
A little typo in my comment should have started with "57 T-Bird spec cam, ..."
Seems like maybe the ECZ-AD carb will work. Going to continue researching. The box that contained this carb also has one off a Rambler that had a 327 in it. My uncle labeled them nicely.
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By 55blacktie - Last Year
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napa, I recommend arranging with Sal Scicala to rebuild the ECZ-AD carburetor and using it, unless you can obtain a proven bolt-on carburetor for less.
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By Tealy64 - Last Year
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Sounds like we have a winner. I just watched the Summit carb swap that the HotRodReverend did on his Tbird and it looks like a fairly simple operation. I'll have to wire up an electric choke, but I imagine there's enough help out there on the 'net to get me by. I checked out Summit and they've got those 500 cfm carbs on backorder until June. That'll give me plenty of time to get this girl back to together and running on stock equipment before we swap it over to the new intake and 4bbl.
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By napaunderground - Last Year
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For completeness, here is the cam card I got. Sadly, I was not as smart when I sent out the stock cam for regrind as I might be now. But it's fine... it'll be great for our application.
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By 55blacktie - Last Year
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If my memory serves me, that's about as close to the 57 312 factory cam as you can get, if not spot-on. The same cam was used in 57 C,D, and E-code engines, but I'm not sure about the F-Code. It will work well with your combination.
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By napaunderground - Last Year
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Cool. Thanks for all the input. I appreciate it, all the time I spent professionally working on modern vehicles didn't much increase my know how about this stuff. Plenty to learn!
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By napaunderground - Last Year
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So, I am going with the general recommendation to use the factory '57 T-Bird carb. Does anyone have ideas as to it's flow potential? It's a 4150, that's the best I can find. The internet hasn't provided an answer, I am just curious. ECZ-AD List 1273-1
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By 55blacktie - Last Year
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The 55-56 Holley 4000 "Teapot" flows 390 cfm. The 57 4150 (1st year for same) flows approximately 465 cfm. Although the 57 carburetor is a 4150, it more closely resembles the 4160 carburetors. The replacement Holleys that the Tbird suppliers sell is a 4160 that has the same cfm rating. The new 4150 carburetors are dual-feed/w fuel lines on the passenger side. The 4160, like the 57 carburetor, is a single-feed on the driver's side.
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By napaunderground - Last Year
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Awesome, thanks!! Again!
For only 45CFM difference in max flow from a new 500CFM carb, I definitely am more interested in using the vintage carb.
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By 55blacktie - Last Year
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Depending on the condition of your carburetor, it might/might not be rebuildable. Someone like Sal might be able to "tweak" it so that it will perform better than new, if it can be rebuilt.
CORRECTION! According to Ted, the 57 carburetor is 410 cfm, not 465. He would know better than I.
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By FORD DEARBORN - Last Year
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A regular on this forum with a 55 Bird and what I would consider a build that is a good level above stock running a 390cfm Holley has always had praise for that carb. I think it's FloridaPhil.
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By 55blacktie - Last Year
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Napa, I sent a PM. I hope it helps.
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By Ted - Last Year
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Always keep in mind that the cfm rating of a carburetor is not the only determination for selecting a carburetor. While the original 1957 Holley (List #1273) is rated at 410 cfm and the replacement Holley for the 1957 Thunderbirds (List #1848) is rated at 465 cfm, the replacement carburetor exhibits better low end torque and drivability aspects than the original due to improved metering aspects. While he peak horsepower is the same for each, the torque is much better with the replacement carburetor. Torque is what you feel when just driving the car around.
That’s a lead-in now for the larger carburetors and especially the Summit series or line of carburetors which is a modern revision of the older Ford ‘flat top’ carbs. Besides the internal circuitry having the advantage of sixty plus years of improvements, the fuel discharge nozzles have also seen a redesign and improvement. The Summit carbs have annular discharge nozzles for the fuel versus the ‘straight leg’ nozzles you find in the original and replacement Holley’s. The annular discharge nozzles do a much better job of atomizing the fuel droplets as they enter the venturis versus what is observed on the straight leg and drop leg nozzles. With that improved atomization you get an increase in fuel efficiency or fuel burn which translates into more power also. The torque numbers also go up accordingly.
Also keep in mind that a vacuum secondary carburetor is only running on the primary side in normal driving. With even a 750 cfm sized carburetor, it’s only utilizing half of that until the secondaries start to open. The secondary side opens only as demand in the primary side dictates that so if the engine does not need all the available cfm, the secondary side only opens the amount required. While a double pumper carb is very rarely sized exactly for an engines’ demands due to rpm and/or varying climate conditions, an oversized vacuum secondary carburetor will always be spot on in regard to what the engine wants regardless of the rpm and/or varying climate conditions.
Just some early morning ramblings so don’t let this be the end all for this discussion.
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By DryLakesRacer - Last Year
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When I decided to use 2 of the Holley 2 barrel carbs I’d raced that never had been on a street engine and add one with choke housings I found we could never get the engine to a repeat idle. With starter fluid and a WD40 plastic tube I found all 3 shafts leaked excessively on both sides. With a bushing kit and inner nylon wraps I was able to seal them.
I write this because older used carbs base plates if aluminum do wear and it’s hard to get some correct. I’m sure the rear barrels of vacuum secondary card will probably be good but it’s something to check when using older ones.
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By napaunderground - Last Year
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Going to do some further inspection on the carb next week. On the outside, it looks pretty low miles... but I haven't dug in deep yet.
For now I likely will use it, then do something else later if it seems prudent.
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