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Carb recommendation for a 460 Ford.......
I need a good recommendation far a carb on a Ford 460 engine. The engine is out of a 77 Lincoln Mark V and is going into a 78 F250 with a 4 speed trans. The motor is all stock with 8:0-8:5 compression, except for the double roller timing chain I put in at zero degrees up. The 460 has to only turn a alternator and a power steering pump, this is two less accessories to turn when it was in the Lincoln. I live at a elevation of 5500 feet and don't need as much cfm as per say sea level. The truck is going to be pulling a twin axle 18" flatbed trailer everyday around town(work truck). I would like to get the best milage possible but on the other hand I will need the power at times. The stock carb was a 600 cfm Ford Motorcraft 4350 four barrel spread bore carb(junk). I have a adapter plate to fits a standard four barrel Holley or Edelbrock carb on the stock spread bore intake. I was thinking maybe a 650 vac sec Holley with a electric choke or would a 750 Holley or Edelbrock be better or too much? Any suggestions would be appreciated.
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For the intended use the 650cfm will be fine..have run that combo on a 460 and it worked well..
Sam
__________________
I have tried most all of it and now do what is known to work.. |
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If you're after economy, torque and power to suit a spreadbore manifold why not a q-jet? Should you get one off a late 70s c20 454 I reckon the jetting and needles would be nigh on perfect ( 455 BOP would work also).
Sometimes people fit a small carb to a large engine to get torque and economy which does work, but you must check the application the carb was designed for - a 302 uses smaller idle passages and acc circuit than a 460 so it's hard to make the same carb work down low on both when they may work fine at 1/2 or wot. Same goes for different compression ratios or rod to stroke ratios. A low comp engine has less air speed and therefore poor carb 'signal' same for a long rod engine so they needa greater restriction (small carb) too work. My first choice would be a q-jet on a spreadbore then a 750 (3310) vac holley on a small runner dual plane. |
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... To fit a QUADRA-JUNK onto the stock manifold would be most difficult (sets atop an EGR plate). Of all the carb options out there, a Q-JET would be my last choice. Leave that stuff for the BOWTIE BOYS...
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What carb?
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I really don't want to try to adapt a Quadrajet to my 460, it would be too much work and time adapting it to my 460. I even had one about 6 months ago, it came off my dads 400 sb Chevy, sold it on Ebay, didn't need it. There is no way I am going to put that Motorcrap 4350 back on the motor, the only thing it would do is idle. I didn't think a 750cfm carb would be all that great on my 460, I will most likely get a 650cfm Holley for it. I also like the idea about installing a 5 speed in my truck, that would help quite a bit on the fuel mileage.
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The problem with putting a small Holley carb on a big engine is air flow requirements at idle. If the front throttle blades are opened too far to allow enough air in at idle, it will put the carb into the main circuit. This will make it run very rich at idle and the air/fuel mixture screws will not do anything. However, this problem can be solved by opening the rear secondary throttle plates a little bit with the secondary plate stop adjustment screw that is under the carb. Open the rear plates slightly until there is no vacuum on the ported vacuum source. Of course, since the secondary plate adjustment screw is under the carb, you will need a few carb removal and re-install jobs to get it adjusted right.
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600 - 650CFM is plenty big
I had a '79 F350/460 and thought I was doing myself a power favor when I took the original Holley of the truck and put an early 3310, 780CFM Holley on it before a cross country trip hauling an 8000 pound 5th wheel camper. It did kinda OK except for much worse gas mileage until I got to the Colorado mountains where it went from kinda OK performance and worse gas mileage to horrendous in both cases. Too much venturi with not enough atmospheric pressure which equals no atomization and raw gas and a diesel looking exhaust. I fiddled with float settings, squirters, jets, springs, accelerator pump settings and it still ran crappy. When I got home, back went the original carb - which is about a 575CFM unit. Eventually I installed an extra Edelbrock 600 CFM that i had - and it was the magic bullet once I got the settings correct - pulled the camper well, and got acceptable gas mileage in all cases.
This is the original which I still have (it's for sale-cheap) Dave |
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Your engine is stock.
Hopefully your timing chain upgrade eliminates the factory 8* retard. That helps a lot. I bought a new 460 back then and put in a 71 timing gear. Felt like 20 more across the board. Using all the formulas for carbs, a 600 is plenty. You will rarely ever exceed 4500 rpm. The valve springs are probably done at 4500 anyway. I recommend a vacuum or air valve secondary. I prefer an Edelbrock/Carter for ease of tuning and lack of body leaks. The AVS is easily adjustable. I think that they still market a spreadbore, but not sure. Don't open the secondary too easily and too soon. Ditch the EGR stuff and use good headers. Improperly tuned, any carb will be disappointing. If you don't have someone who can tune and adjust whatever you choose, you are just going to join the club of "that carb is crap, so I bought a xxx". Been there, done that. |
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What he said!!
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Sam
__________________
I have tried most all of it and now do what is known to work.. |
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I agree, leave the Quadra "Junks" to the Bowtie Boys, we don't like to share the good stuff. Seriously my kid has a '78 F150 4 X 4 with a 460 out of who knows what with a C-6. It's a cobbled together abortion I not so affectionately call the "Exxon Valdez" due to the rather large oil slick in my driveway........ It has headers, who only knows what for gears and 35" mud tires but the old slug actually runs pretty good and pulled a car trailer pretty well, it has an Edelbrock 625 on it now in place of the well violated 600 Holley it had on it when he bought the thing and it seems to like it. |
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xntrik, I bought a Ford Motorsport double roller chain for this 460, it has 2, 4, 6, 8 degrees in retard and 0, 2,4,6,8 degrees for advance. To advance the stock cam 8 degrees, do I set it at 0 or do I set it at 8 degrees advance?
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BUUUUT in truth there was minimal power difference from the 73 400 in the identical vehicle, and the 460 got 2 mpg less. Degreeing would be the best. In lieu I think zero is probably correct. I would go to 2* advance to allow for some wear and stretch. I have done 460s since, but nothing with a stock cam. If you really want to pep it up, CompCams has a really good 4x4 grind that really helps across the board. |
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