Got a used Edelbrock 1405 carb for a song, rebuilt it (and got the tuning kit) and would like to use it on my '63 Fairlane. Got a Jeg's house brand dual plane aluminum intake but everything else on the freshly rebuilt 260 is stock.
Can I tune down this 600 cfm carb to run on my 260 or is it simply too much carb?
Thanks
Not too much, but you might have trouble tuning it for WOT. The smaller cubes means the air might not have enough velocity for accurate vacuum across the venturi. You can always rig up a stop to prevent it from the secondaries to go the whole way open, or just adjust the throttle cable.
Pay extra attention to your idle. Make sure you have enough/proper ignition lead so that the primaries are as far closed as possible at idle. With smaller CIDs the transition from idle to off-idle will be key to preventing a bog.
Take a tuning hammer to it and buy a Holly . OK..I have to admit I had one and it was OK, till the screw came out that holds the metering rod .
Thanks!
My understanding is the weighted air valves on the secondaries maintains proper velocity on an as needed basis.
Agree about ignition and primary butterfly position. Edelbrock's have two ways to adjust idle (linkage and needle screw) so hopefully that will help.
My concern is if I need to go down on the primary main jets and metering rods.
Dang, Scott! My metering rod plate screws were on there pretty good.
Generally no. Many say bigger motor needs bigger jets, but a bigger motor sucks harder (thus draws more fuel). For a small motor big carb deal the jets may actually need to be bigger because it does not suck as hard.
Leave it alone get the idle set and timing good then take to dyno for final tune. Or you can tune it by the seat of your pants, but you have to make only one change at a time and drive it for a bit (a few days to evaluate) Then try another change, work with the rods only if you can. Or find a matrix that shows you what the different combos do. Lots of time and trial and error til you get it right.
You should be able to get it to work on the 260. Might not be ideal, but it will work. Or toss a bigger cam in there to take advantage of the carb. 
If you don't have a copy of the Ed carb manual, here it is. 1405 charts are on page 11. Study up on the idle circuit before messing with the chart.
Confirm the rods, springs, and jets are all stock pieces in your 1405. They probably are, but since it's used who knows what was done to it earlier. Stock is a good baseline.
Get the idle set. The idle circuits come into play more often than you would think.
Disconnect the linkage to the secondaries. It's on the passenger side of the carb. Concentrate on the primaries first. This way it's just a big 2 bbl to start messing with.
With the primaries sorted out reconnect the secondaries and see if it's running fat or lean. The weighted air door will help with avoiding bog. Take a look at the weights on the air door. Make sure they haven't been cut up to lighten them.
We have a 1406 on a 267, and a Holley 650 HP on a 260. Yes you can tune it to work.
You will likely end up with the blue springs, biggest jets and smallest rods. Small engines have weak signals. Especially if you buy todays pump gas that require extra fuel to compensate for the corn pee. On the 267, we dropped 3.5 seconds off the 0-60 time with some work and a bit of tuning. :)
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