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By Florida_Phil - 5 Years Ago
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My 292 TBird has the usual upgrades, "G" heads, Isky cam, 57 distributor, "D" code 4V Iron Intake, Holley 0-1848 465 cfm vacumn secondary 4 barrel, 4.11 gears and O/D. I'm thinking about trying a 600 CFM Holley double pumper for better street performance. Is this a better option or am I going backwards?
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By Cliff - 5 Years Ago
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I would think a 3310 Holley
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By DryLakesRacer - 5 Years Ago
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The Holley 465 is a great carb for street performance especially off idle. What transmission and rear gears do you have? Fun street performance is usually in your gearing and if you have the stock Ford-o-matic a trans starting in first gear will make a ton of difference. It did for me.
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By BamaBob - 5 Years Ago
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What transmission did you use?
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By miker - 5 Years Ago
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Here’s a link to Ted’s carb testing on one of his motors. You’ll have to draw your own conclusions as to how your engine compares. The 465, 600, and 750 are included among others (16 total).
http://www.eatonbalancing.com/2012/09/25/four-barrel-carburetor-testing-on-the-y/
I’ve never been a big fan of double pumpers on street cars, it takes a lot of fuel to cover the flat spot at low rpm’s. Race cars, different story. But opinions vary on carbs, just like cams and mufflers (and everything else).
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By Florida_Phil - 5 Years Ago
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My car is a three speed manual O/D with a 4.11 gear. The 465 is a great street carb. I'm looking for a little more excitement when I hit step on the gas. It seems I'm never satisfied. :>
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By DryLakesRacer - 5 Years Ago
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Bama. I had a 1962 T-bird medium case cruise-o-matic Because of the speedo gear location I had to install the Ford-o rear housing which was machined and rebushed for the larger yoke.
If doing it again I would adapt a C4; direct adapter bellhousings are available
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By ianmatt - 5 Years Ago
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I have a 59 292 bored 30 over and mummert intake. headers pertronix and i believe the rear is 3.25 . origial 4-speed with granny gear. I have had several different carbs on my motor and by far the best overall carb is the 500cfm edelbrock AVS2. idle is incredible, no flat spot, starts like fuel injection. I have been extremely happy with it.
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By Ted - 5 Years Ago
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miker (10/14/2019)
Here’s a link to Ted’s carb testing on one of his motors. You’ll have to draw your own conclusions as to how your engine compares. The 465, 600, and 750 are included among others (16 total). http://www.eatonbalancing.com/2012/09/25/four-barrel-carburetor-testing-on-the-y/I’ve never been a big fan of double pumpers on street cars, it takes a lot of fuel to cover the flat spot at low rpm’s. Race cars, different story. But opinions vary on carbs, just like cams and mufflers (and everything else).
That data in the link posted above is over ten years old and is outdated. Since then, there have been some new players involved when it comes to carburetion for the Ford Y family of engines. If the engine is a stocker, then a small sized carburetor is fine. If never going over 5000 rpms, then a small carburetor is also fine. ‘Small’ being 400-500 cfm in size. If the camshaft, cylinder heads, and/or exhaust systems have been upgraded, then the engines will simply prefer a larger carburetor to capitalize on the new found range of rpms that will be available.
As a general rule for vacuum secondary carburetor selection, always select a carburetor that will be at minimum, oversized for the application. This has to do with the vacuum secondary side of the carb being opened based on engine demand. That means the secondaries will only open as much as required and although the carburetor may be as much as 750 cfm or more when fully opened, it’s simply going to be less cfm if the secondaries are not fully opened based on not being needed or in demand. It's the best of all worlds in this scenario as the larger sized vacuum secondary carburetor will always be the right size regardless of conditions.
That brings us to the double pumper carbs that so many people have a love affair with. By design, they are on the ‘rich’ side out of the box and that’s because they were designed for a racing or high performance application where all the aforementioned performance mods have been made to the engine. It’s a rare day when a double pumper or mechanical secondary carburetor is the ideal size for a street application as they are typically either too big or too small. On that rare day when it’s just right, that can change with the weather the very next day.
I have installed a multitude of vacuum secondary 750 cfm sized carbs on the Y engines and they drive great while providing sufficient air flow for engines running well in excess of 5000 rpms. My overall choice for a 750 carb would be the Summit carb which is a remake of the older Holley 4010 series and that was a remake of the older flattop Autolite/Ford carbs used in the late Fifties and Sixties. These carbs are a modular design not requiring the every three year rebuild a typical Holley carb seems to require.
This years Engine Masters Challenge entry was 303 inch Y with iron heads that used a 930 cfm double pumper (mechanical secodaries) and was making 430HP on the JE Pistons dyno. And that engine combination still managed to surprise everyone by idling at a nice 550 rpms. This engine was taken to 7200 rpm for each of the twelve pulls it made at the competition. That kind of performance was only available by using a carburetor sized appropriately for the increased air flow of the engine.
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By Florida_Phil - 5 Years Ago
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Great info. My Holley 465 performs well, has great throttle response with no dead spots. It doesn't look all that cool. I'll keep my hood closed. 
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By pegleg - 5 Years Ago
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You might try a 600 Vacuum secondary, but you DON'T want a double pumper for street use. Read Ted's answer and the realize Detroit hardly ever used a mechanical secondary carburetor on anything including the Big blocks.
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By Florida_Phil - 5 Years Ago
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I have never owned a double pumper carb in my life. Even my race cars had vacuum secondaries. Seems like a good idea? I'll file that in the "bad ideas" file. Thanks,
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By ianmatt - 5 Years Ago
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Funny cause i was torn between a 650 AVS2 or the 500. I went 500 but from ing this thread I am now thinking I should have gone 650 with my engine.
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By Florida_Phil - 5 Years Ago
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With carbs, it's easy to think bigger is better. If you look at Ted's testing you will see the difference in HP is minimal. My Holley 465 runs great on the stock 57 iron manifold. It never stumbles or has dead spots. My only complaint is it's not a very impressive carb to look at. For looks, it's hard to beat a multi carb setup. I have not had the best luck with these. Over the years, I've spent countless hours tuning Y Block tri powers and playing with old carbs. They look good. In reality they don't work that well. I always end up selling them and running a single Holley. What I should do is hollow out an old blower and run my Holley inside of it. 
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By KULTULZ - 5 Years Ago
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Have it refinished?
Give up on the idea of two fours?
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By Florida_Phil - 5 Years Ago
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If I could find an Edelbrock FM 255 intake at a decent price, I would buy another Holley 465 and give it a try. I'm done with tri power.
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By DryLakesRacer - 5 Years Ago
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I'm confused Phil on your statement "it doesn't look good" . To me it looks identical to any single feed Holley. I'm guessing you want the dual feed look. On my GMC 6 racing engine I use a 650 cfm vacuum secondary that has been converted to dual feed but keeps the vacuum secondaries..A really good carb shop could easily convert your to dual feed and remove the jet plate.
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By charliemccraney - 5 Years Ago
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A 570 Street Avenger will get you a more performance look. Holley sell refurbished carbs on eBay so you can get a like new carb for a better price, direct from Holley.
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By Florida_Phil - 5 Years Ago
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I attend a lot of car shows. Most of these are about eye ball. I didn't buy my TBird to carry golf clubs. I bought it to hot rod. I get a lot of comments on my dog dish hub caps without the fender skirts and most people have never seen an early TBird with overdrive. The cam in my car has a noticeable idle. What I would like is a race engine "look" with reliability and drive ability. I had an Edelbrock FM257, but I couldn't mount Holleys straight and I didn't want to mess with old carbs. Edelbrock carbs don't have the look I want.
An FM 255 sounds perfect if I could find one in decent shape. I would run two Holley 465s in line like a 427 425. I doubt the secondaries would ever open. The manifold would clear my TBird hood and have provisions for a PVC. I believe driving around on the primaries would be spirited. What would be really nice is if someone would make a new FM 255. Dual quad Blue Thunder or Mummert? Nice dream.
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By Ted - 5 Years Ago
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There’s a mold for this one sitting out there somewhere.
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By Florida_Phil - 5 Years Ago
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I would buy one.
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