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Old 09/16/12, 12:35 AM   #1
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Whats the best carb/CFM for a 351w?

I'm having some issues w/ my carb...Holly 4b (650cfm) and I'm thinking I might want to replace it. Already been rebuilt once.
Hoping there is something that will give me better mpg around town (it's my DD). Is there a lower cfm I can get away with that would make a big difference? Not too worried about power's just for in town mainly.
Carter? Eddlebrock?
Any suggestions?
And...anyone have one for sale?

'73 Bronco Ranger, Built 351W, C4, Dana 44, 9" rear, 411's, 35's, Flowmasters and a train horn (beloved by the neighborhood).
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Old 09/16/12, 02:47 AM   #2
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You may want to Clic it over to Fuel injection..if you are going for mileage. The Holley 450 jetted correctly would be my guess..but may not be cheap to find......
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Old 09/16/12, 06:15 AM   #3
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Thumbs up

With the 351W I have had the best luck with a 625 carter. Bill
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Old 09/16/12, 06:57 AM   #4
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run an autolite 4100....very happy with it

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Old 09/16/12, 07:46 AM   #5
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Holley 670 TA is what I am using. I have to agree with our bronco brother above, fuel injection is king for mileage especially if you want to install it and forget it. A carb can be tuned to get nearly as good of mpg as fuel injection but would require more maintenance to maintain that good mpg. Greater mpg with a carb usually means a little less power but this is usually not the case with fuel injection, infact it can mean more power as you increase efficiency with better/performance parts.
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Old 09/16/12, 07:48 AM   #6
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autolite 4100 one with part # C6AF-L would be perfect.
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Old 09/16/12, 08:28 AM   #7
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I have a 1406 Edelbrock with diff jets, springs and meetering rods.

72 74 79 93 so far
2008 sorta just a week early
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Old 09/16/12, 09:04 AM   #8
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650 Holley, is that a double pumper?
Most out of the box carbs are set up to run a little rich, safer for the engine. So anything new will require tuning to get it dialed in. Even used carbs will need tuning to match your engine.

A good MAF EFI will be a choice that shouldn't need tuning. Trick is to keep all the stuff matched; MAF, ECM, injectors. The MAF has a specific voltage out for a specific airflow through it. Alter that relationship (change housing size, different sensor then the computer is programmed for, etc.) and you just lost your tune. For a stock 351 you can use a truck lower, BC adaptor for a 5.0 upper, stock mustang 19Lb injectors and have a nice clean efficient running engine.

"She's built like a steakhouse but she handles like a bistro"-Zapp Brannigan
“How hard can it be?”-Clarksonius 4th century BC.
Full throttle, it either solves the problem or ends the suspense.
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Old 09/16/12, 07:16 PM   #9
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Great... I'll check these out, thanks guys! By the way, how hard/expensive is it to switch over to you inject shin?

'73 Bronco Ranger, Built 351W, C4, Dana 44, 9" rear, 411's, 35's, Flowmasters and a train horn (beloved by the neighborhood).
VOTE for as the top 4x4 site!: CLICK HERE
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Old 09/16/12, 11:53 PM   #10
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With a properly tuned carb you are not likely to see much if any increase in mileage by swapping to EFI.
A smaller carb will increase lowend throttle response but wont always be more effiecent. I would suggest going with a 600 cfm carb and tuning it then going from there.

EFI swap prices are all over the board they can be done for next to nothing if you can score the parts or it can run into the thousands if you went all new. but IMO a basic stock for setup will probably cost you around $500 unless you go with a new wiring harness which will raise the price up about another $500

73 Ranger 2 1/2 lift 302 TFS heads NP435,PS,PDB, tierod over, 33x10.50x15 BFG M/T
71 Sport 63,000 miles all orginal except for cut fenders 302 3sp 4.11's D44/BBTrac lok rear
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Old 09/17/12, 07:05 AM   #11
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That carb may have been rebuilt, but never really tuned right. I love my Holleys. Ive had people jump in and go for a ride in my 74, and then ask if its fuel injected!
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