best carb for 283. 500 or 600 cfm

my 68 biscayne 283 3speed manual has an old carter. Runs good but maybe a tad rich. I thought of buying a 500 cfm edelbrock for a little better mpg, car is a cruiser, hwy gears 65mph 2500rpm.. Just rethinking size if I get a new carb. The formula I get shows 450 cfm.
mods to motor are dual exhaust, 266 crane cam, performer rpm intake, 305 heads, HEI, Anyone ran a 500 cfm on their 283?

 

I am running a 500 CFM Edelbrock on my 355 SBC in a '48 Buick Roadmaster...it runs great and gets over 20 MPG! I have rejetted the carb two steps lean.

 

If your just cruising a stock 283, a 500 cfm should be just fine.

 

I have a 500 on my 305. Perfect. 28 mpg.

As you will find frequently mentioned, with ANY Edelbrock carburetor, when you get it, pull the top off and clean out any crud, from use, or manufacturing. Then set the float levels. No exception to both of these, even if it is used.

Also, run a pressure regulator. These carbs are sensitive to over-pressure. 4.5psi is good.

Then, and only then, can you start in on tuning with confidence.

 

going for more efficiency, tuning your existing carb will do the trick.

500 or 600 is not a big factor there. Overcarbed by a little is no big deal.

Even with a new carb, you will still need to rejet for lean to maximize the carb.

 

i have a 500 CFM Edelbrock 1404 on the 283 in my `36 and it runs great , plus i get good fuel mileage

 

Definitely a 500cfm

Frank

 

Remember, the cfm rating is the maximum ammount of AIR that can flow through the carb. If you don't have your foot on the floor at wide open throttle, there will be no real diffrence.

Keep your 600 and invest 40 bucks in a metering rod/jet kit from Edelbrock (which works with your Carter AFB series.) Follow the instructions and not only will you learn some cool stuff about carbs, but you will also maximize your mileage. Even more importiant than that, you will learn how to make MORE POWER.

Plus, you save the cost of a new carb..

Good luck, -Abone.

 

Carter recommended and sold a 400 CFM (part number 9400s, superceded by 9410s) for use on the 283.

Jon.

 

Chevy also offered the 283 with two four barrel carbs,a mild cam engine 245 hp and the hotter 270 hp .That's about 750 cfm for those two WCFB's I believe.The 283 this poster has is probably a bit hotter than the 245 hp two quad engine.
A smaller carb will likely work better on a heavy car that won't have the snot wound out of the engine all the time

 

This is good advice. I don't think it matters much between 500 & 600 as long as it's tuned right. I'm running a Carter 600 on a 283 with no issues.

 

id like to bring this one back to the top.

My 600 cfm edelbrock works great down here in the Sacramento area but this past week i went up to reno for hot august nights and i leaned it out but it still idled choppy the entire trip no matter how dialed i got it. the second i came back down to the Sac area, it idled better than ever.

should i down size to a 500 or just get the kit like fordor ron mentioned?

 

Hey!! I run a holley 390 CFM on my 305-350 trans in a 1937 chevy truck. stock discharge nozzle is 25,went to a 28. stock jets are 51,went to 55. runs great,never checked mileage. Pete

 

I too vote for a small (450-500 cfm) Holley.... Ford, GM and Chrysler used those on production cars...

 

What's the elevation difference between Sacramento and Reno ?

Have you ever seen "two lane black top" ? " I gotta change the jets" happens a few times in that movie as their elevation changed. Air is thinner =less fuel or smaller jets.

 

1951 ford with 305 with 327-300hp cam, turbo 350 transmission and 2.79 rear gear ....I got 24.6 mpg with this NON-overdrive car running 70-75 mph on the interstate.

I ran a quadrajet with my own custom rods and jets....it was a 7043202 with 42 rods and 71 jets.

My 49 Fleetline will have a 283 currently being machined and I have already built a quadrajet for it...I think the same carb number with 41 rods and 70 jets( one lower than the 305). It will have 700R and 3.42 gears, 601 z28 heads, and 327-300hp cam...looking for 30mpg.

Here is the 51 ford video....it ran really nice....sorry, the car was sold and is close to Greensboro, NC now.

http://www.youtube.com/watch?v=ZQZbHtfiivI<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>

 

Your didn't state which, so your old Carter may be a WCFB is the predecessor of the Carter AFB, which is the predecessor of the Edelbrock.

Bottom line, there's no magic in a later Edelbrock which can't be duplicated by a freshened WCFB or AFB. Any of the three would have to be tuned for best MPG.

Second point - on the street, through the mufflers, smaller CFM is better. The WCFB is around 400-450 CFM.

jack vines

 

This is good advice, unless your old carb is wore slap out there is not real reason to buy a new carb when the old one can be repaired @ 1/3 of the cost (or less).

If the old beasty is running a little fat it may just need a new needle and seat and or a float adjustment.

We just cleaned up a 15 dollar swap meet carb for the cost of a kit ( about 40 bucks) and it works like a champ. Of course we could have dropped about 400.00 for a new replacement for the old carb.

 

Many people are a bit hesitant to rebuild their old carb... me, I send out my Q-Jets since I'm more miss than hit with them. Everything else I'll tackle especially when back in the day I had more time than $$.

Bob

 

Running an Edelbrock 1405/Performer intake on a .040 over 283 with original heads (1.72/1.50) Comp Cams 268H, Mallory distributor (w/ Crane Xr700 electronics) in front of a T-5. Had to jet it down several steps and it is still a little rich but gets 21 mpg average at 70-75 running a/c in our '58 Apache with 3.73 gears and 275-60-15 tires

I wish I had the 1404 but am not willing to buy a new carb.

 

Sacramento is like 25 ft and Reno is 4400 ft.

And no i have not seen that movie but i believe it. I do think i need smaller jets for when i move up there.

 

I believe a 450 Edelbrock is still available and would be perfect

 

One of the really nice aspects of running Carters.

You don't need to change the jets, you change the metering rods (step-up rods in an AFB) instead.

Carter's original calibrations:

Standard - sea level to 4000 feet
One size lean - 4001 to 6000 feet
Two sizes lean - 6001 to 7000 feet

How difficult is changing metering rods? While not recommended, to prove a point, I have changed them with the engine running.

Jon.

 

My 500 works great on my stock 283.

 

I love Carters but run a Holley with the fresh 283 I dropped into my 47 Chevy. Specs are +.040", mild hyd stick, cleaned up 305HO heads and 9:1 CR with an Eddy Performer Intake and I added the Holley 465.

Mounted it on a 4 hole phenolic spacer to keep her kool and add tad more throttle response and dialled her in with a vac gauge, run std jetting and runs like a champ with clean plugs. Have'nt done a mileage run yet but I expect good things.

I reckon the 465 vac sec with its venturi /throttle bore size is the right carb on a mild street 283 with rams horns/full exhaust. Esp on an engine that ain't gonna be turned hard.

Rat

 

Well, I typed every thing out only to lose it when I hit post. Whats with that? I will try again
<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <wunctuationKerning/> <w:ValidateAgainstSchemas/> <w:SaveIfXMLInvalid>false</w:SaveIfXMLInvalid> <w:IgnoreMixedContent>false</w:IgnoreMixedContent> <w:AlwaysShowPlaceholderText>false</w:AlwaysShowPlaceholderText> <w:Compatibility> <w:BreakWrappedTables/> <w:SnapToGridInCell/> <w:WrapTextWithPunct/> <w:UseAsianBreakRules/> <wontGrowAutofit/> </w:Compatibility> <w:BrowserLevel>MicrosoftInternetExplorer4</w:BrowserLevel> </w:WordDocument> </xml><![endif]--><!--[if gte mso 9]><xml> <w:LatentStyles DefLockedState="false" LatentStyleCount="156"> </w:LatentStyles> </xml><![endif]--><!--[if gte mso 10]> <style> /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} </style> <![endif]--> To start, I have a 65 ranchero with a 86 5.0 and aod trans in it. It is stock other than a air gap intake and a edelbrock 4706 &#8220;600 cfm&#8221; carb on it. The air gap may change the results a little since edelbrock does not recommend this carb on a air gap intake. My truck runs great with the 600 on it and averages between 25 and 30 mpg on the freeway. I have been hearing about how much better a 500 carb is over the 600 for small blocks. So I figured I would see for my self. I am pretty good with the edelbrock carbs. I have a pair sitting on my 440 as well. First thing was to get a 500 carb to use for parts. I found a good carter 500 to use. I have .095 main jets in mine but it is jetted very close to a factory 600. I only had to add a set of 73/52 metering rods to get to the 500 specs. First drive was disappointing. It felt like it was starving for fuel. Kind of like when I leaned my 600 out while doing it. I pulled the metering rods and put a set og 73/47 rods in. A big difference in a good way. I could feel at about 2k and up now. It was just a little crisper than the 600 was. I then changed to 68/42 rods. I didn&#8217;t have any 73/42 rods in my kit to keep the idle circuit leaner. What I found is if you kept jetting up. The lower was stronger than the 600 was stock. I never tried jetting my 600 for power, but feel if I jetted it up. I could easily match the 500.
If I wanted max power, I personally would go with the 500 since it pulled harder than the 600 when you had your foot in it. In the end. I was jetted up more than with the 600 and lost a little in fuel mileage. My ranchero is just a cool daily driver for me. I have my fury if I want to go out and fry tires and haul beans around town. I have changed back to the 600 since it worked perfect for me. No sense in ruining a good 500 carb. I figure some one else down the road may want a good deal on a 500.

 

Did you remember to check the box "Remember Me" when you logged in?

 

probably not. I have never had to on any sites if you didn't leave them. I will make sure I do next time. Thanks

 

Im running a 1405 600 CFM on my 283 bored .040 over, headers and performer intake, Jacobs Pro Street Ignition, 274 Energizer Crane Cam, 3.73 gears and a TH350 trans which Im about to switch to a 700R4 for gas milage. Anyway I have been working on leaning out my carb over the past week. I actually installed an oxy sensor in one collector and K&N air/fuel mix gauge which I totally recommend. I think I have the perfect combo for now.. This is what I have. .098 mains, .073x.052 Rods, .095 Secondaries, and Orange 5hg. step down springs. Hope this helps.