about time for a new carburetor

jlangholzj · Sep 26, 2010

so, I finally winterized the old girl yesterday. And it had me pissed off. Its been really contankerous this summer and just a general pain. Doesn't like to idle very well, chokes and sputters, I figure it just time to get a new carb instead of trying to rebuild and nurse along the old abused one i have.

So here's what I got:

3.00 rear gears (3.73 in near future)
AOD

mostly everything in the engine is stock
no head work
mild RV cam
performer intake

I'm looking at one of these:

Holley 0-81570 - Holley Street Avenger Carburetors - Overview - SummitRacing.com

Holley 0-1848-1 - Holley Model 4160 Adjustable Float Carburetors - Overview - SummitRacing.com

I had a 600 on there...and no question that it was some overkill. I want my low end back some. So my question is should i be looking at the 570 or the 465 ? All of my driving is street with no real "track time" just spirited driving so no need to worry about choking it out in the top end.

ideas?

rbohm · Sep 26, 2010

stick with a 600 cfm carb, but i suggest the 1406 edelbrock carb. those things are super reliable and easy to tune.

2+2GT · Sep 26, 2010

I agree. What carb do you have now? Might have a bearing on advice.

htwheelz67 · Sep 26, 2010

600 is not overkill at all but out of all the carbs I have tried even custom built ones the demons have the most performance and features for the money, a road demon 525 with annular boosters will give you efi like throttle response and will still flow about 600 cfm.

Road Demon

I have bought all of mine on ebay (remans) for a great price and they ran perfect right out of the box

have you tried advancing your timing a bit?

http://www.carcraft.com/techarticles/116_0508_carburetor_showdown/index1.html

D.Hearne · Sep 26, 2010

The 570 is perfect for what you're doing. I have one on a roller 5.0 in my 89 Ranger (ported E7 heads, stock F4TE cam, Shelby tri-Y headers, sitting on a Ford A321 intake) Mixture is as perfect as you can get as is, straight out of the box. The only thing I did was install a lighter sec spring.

Realmongo · Sep 26, 2010

To give you a benchmark, Ford put 1.08" Autolite 480 CFM carbs on the A code 289 engines and 1.12" Autolite 600 CFM carbs on the K codes which gave them the ability to pull to 7000 RPM.

htwheelz67 · Sep 26, 2010

Realmongo said:
To give you a benchmark, Ford put 1.08" Autolite 480 CFM carbs on the A code 289 engines and 1.12" Autolite 600 CFM carbs on the K codes which gave them the ability to pull to 7000 RPM.

And Carrol Shelby used a 715cfm holley........

Realmongo · Sep 26, 2010

htwheelz67 said:
And Carrol Shelby used a 715cfm holley........

Holley rated the 3259 at 725 CFM that was put on the early manual transmission cars, while other sources state the 715 CFM value you quoted. The Shelby cars with the autos stuck with the 600 CFM Autolite carbs including the Hertz versions. When Mustang monthly set out to test them on a stock 1966 GT 350, the 3259 Holley ran 15.95 at 88.67 MPH, while the 600 CFM Autolite ran a 15.794 at 90.504.

65FBE2 · Sep 26, 2010

I just Dynoed a 347 with alum heads and large solid cam .560/255@.05 that made north of 450hp. We tried 3 carbs and measured air flow through each. The 650 Demo out performed all others. The other carb was a 750 holley with a Proform main body,metering plates and base plate but only by about 3 hp. The third carb was a 950 Holley which the dyno guy said is really a 825 cfm. I,m not sure what the dyno guy was looking at but he said the even with the 650 the engine was not carb limited. Unless you have a solid cam and plan to twist it to 7000 rpm. I am now convinced that the 480 Autolite is perfect. I bought one from Pony carbs for my 65 convert that is basicly stock(over $500). A cheaper alternative would be the demon 525

65FBE2 · Sep 26, 2010

By the way, not just any old Autolite 1.08 will work properly on a 289. I had one that was for a 352 and it was a real dog. I found out that the secondaries open very late if at all when these carbs are used on a289. If you want one, just make sure it was factory installed on a 289 and not a big block or it will have to be recalibrated and then you are paying the big bucks for someone who knows what their doing.

jlangholzj · Oct 1, 2010

sounds like 570-600 is the way to go I was just worried that 600 was a bit overkill for my motor. Right now it runs so much like **** that its hard to tell anyway. When i was running decent i noticed it lacked initial response. Then again it was a used carb and an old one at that. I tried rebuilding it and even with a stone filter problems keep arising. We just put a 670 avenger on the camaro and it seems to really like that. like...REALLY like it lol. anyway, definately going to order one up this spring.

robbz28 · Oct 1, 2010

Yup, 600 4bbl is great, because the factory 2bbl was around 280 cfm, with the 4bbl you get 300 cfm to cruise around on, and an additional 300 on tap if the vaccum demands it...

68RCodeConv · Oct 8, 2010

If you don't want to fiddle with it get an Edelbrock. If you don't plan to rev it above 5000 then I would get a 500 cfm. Otherwise get the 600 cfm.

Watch ebay and you can get a barely used on in the box for about $175.

about time for a new carburetor

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