I was going over the Specs on the Edelbrock AFB's and noticed that, other than jet/metering rod sizes, the 1403/1404 500CFM carbs are identical to the 1405 600CFM cabs. Both have the same primary/secondary venturi diameters, identical primary/secondary throttle bores, identical pump nozzle diameters, needle/seat, and step-up springs. Any thoughts on how, except for jets/metering rods, one could flow 100CFM more than the other?...
....more of that 'fuzzy math' our friends like to use... If the venturi and throttle bores are the same then Giovanni Battista Venturi, (1746–1822), would probably argue that they flow the same. .
Probably a different booster venturi. Provides a stronger signal to the metering well, but more restrictive to airflow.
i guess we are going to disagree on that...where are you coming up with the bore sizes? i don't see that info on edelbrock's website. i'm going by the 1404 and 1405 i have right here
"100".Haha. What he said! Yes,the boosters are different sizes. Doesn't take much in the venturi to make 100 CFM more or less.
All I can say is I think the primaries on the 500 are smaller. I swapped my 600 for a 500 and the primaries looked smaller to me, I did not measure though. I will say this, I am running a wicked cam with about 10hg/in vacuum at idle and the 500 idles and responds better even though I gave up some top end Mark
Which is exactly what you'd expect from a smaller CFM carb. Way more streetable with a big cam but the top end will suffer. Now you get to decide where you want your performance, in the mid range or WOT. How much time do you spend at WOT vs cruising at part throttle? Frank
36-3WINDOW - I got my info from the Edelbrock Carb Owners manual on page #9...unless I'm missing something... http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf
I'm going to put these 500's on a 6-71 on a 291 Hemi. I'm HOPING they'll be fine. I went with the smallest AFB style carbs I could find, since the engine cubes are small. Just wondering on the 500/600 though...
I have several 500 and 600 afb's and the difference in them is the primary boosters. The boosters on the 500 are smaller id and larger od therefore restricting the amount of airflow through the same size venturi. You can swap the boosters from a 500 into a 600 and..... you guessed it...your 600 is now a 500 and vice versa.
Yes, its a trade off, but the car is much more fun and easier drive with the 500, so thats what I have kept on it. Whats the point of screamig at 7000RPM if the car bucks and shdders getting there? I should have just run a closer to stock cam. Mark
Found this LINK -mhttps://www.ebay.com/itm/CARTER-EDELBROCK-AFB-CARBURETOR-600-to-500-CFM-CARB-RESTRICTORS-PRIMARY-SIDE-/274478419807?hash=item3fe8304f5f%3Ag%3AK%7E8AAMXQJRhRZk%7EF&nma=true&si=4HczDouz6Kk9lHrhI4q5%252FAQOPTg%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557 AUCTION IS FOR 2 PRIMARY RESTRICTORS WILL TAKE 100 CFM OUT OF THE PRIMARY SIDE FOR WEBER MADE AFB CARBS (CARTER/EDELBROCK) WILL CONVERT EDELBROCK/CARTER AFB 625/600 CFM TO 500 CFM SOME CARBS MAY NEED THE CASTING FLANGE FILED OFF OF THE BOOSTERS TO FIT. THESE SLIDE RIGHT OVER MOST WEBER MADE AFB CARBS THE 1405/9605 CARBS WORK WELL WITH .086" JETS (70-47 RODS ARE STOCK) 1406 WILL NEED .089" JETS (75-47 RODS ARE STOCK) YOU WILL NEED TO TUNE YOUR CARB SO IT RUNS FOR YOUR APPLICATION USE JB WELD TO INSTALL
409’s had 2 400’s as I remember and seemed to work just fine. Getting tough to find now and bigger buck$.
Hey I don't think the age matters, I used to tell my service manager all the time when the vehicle manufacturer used to come out with "new" tests "Ohm's law didn't change, why we need a new test on it" Should be same for CFM's haha
The Jalopy Journal
