I have been having a lot of trouble with my trusty old Edelbrock 750 cfm AFB carb here at high altitude in ABQ. I tried every jet/rod combo on the planet, and it was still too rich.
I gave up and bought a new Edelbrock 650 CFM AVS and mounted it to my Mopar M1 dual plane intake. I was able to get this carb adjusted pretty well right out of the box, it just needs larger accelerator pump nozzles to cure a slight off idle stumble (I'm going to install the .035" set in lieu of the stock .028").
Feels much more "torquey" now...can't wait for the weather to warm up some more so we can enjoy some top down cruising.
I'm betting your fuel mileage will pick up with this carb also. This is one of the best designs ever for a carb. Great to see Edelbrock building this. It would be nice if they brought back "strip kits" like we had from Carter years ago. Some of those kits are $100-$150 now. I used to scour the wrecking yards years ago for AFB,AVS's and T-Quads. I would drill out a variety of nozzles,jets,file rods,etc. and it was fun.....can't see myself doing all that now......
yeah, I have the kit for the 750 AFB and the jets are all huge compared to the ones in the kit for an AVS. (standard primary jet in the 750 was a .107, in the AVS it's a .092)
I changed the oil yesterday, 8 qts of Quaker State Defy 10W-30. Now she is billowing white smoke (almost like the carb is too rich) and stinking up the entire neighborhood. I know the old all original short block is a bit tired and has some blow by, and the heads are new which will often show how worn the rings are, but this is ridiculous !! Must be something in that "Defy" oil that is prone to burning (much more than the diesel oil I have been using: Valvoline Premium Blue 15W-40).
On a side note, I forgot to mention when I first installed the new carb it immediately flooded. The floats were way off: they are supposed to be set at 7/16" with a 1" drop, but one side was at 3/16" and 1.5", the other 1/4" and 1". One of the primary air horns wasn't tightened either...so whoever rebuilt this "Factory Reconditioned Carb" needs as a$$ whooping! (I bought it through Summit Racing for $50 cheaper than a new one).
Moral of the story: take them apart and check everything before you bolt it on.
Turns out it was the carb after all--needle/seat were stuck wide open, letting fuel dribbling out of the primary venturis at idle. The needle valves were getting stuck in their housings, because whoever installed them (with gorilla strength) mangled up the opening just enough to cause the needle valves to stick. I had to run a 1/4" drill down the throat of the housing to smooth them out so the needle valves could open/close smoothly.
Also one of the plugs in the front (just above the mixture screw) was pulling air into the primary circuit. 1/4" punch and my trusty BFH tightened it up nicely. Billowing white smoke is gone.......
