rebuild Autolite carb or replace with a Holley ??

[ofairlane]

Guys and gals, I have a 65 with the 390 and 4bbl carb Autolite. The cars doesn't run bad but I am thinking about replacing the carb and possibly the intake with a Holly setup, possibly with an Edlebrock carb, somewhere around 600-650 cfm.
Questions, is there some mod's I have to do with the cooling system ? I see that cooling hose that goes through that spacer on the intake and wonder about that. Also, is this a upgrade in horsepower ? I assume that my Autolite carb has a much smaller amount of cfm's so I am thinking more air means more fuel which equals more horsepower.
I can also just rebuild my Autolite and I know the car will run better but I am thinking the swap would be a good upgrade.
I am a better than average shade tree mechanic so throw your thoughts and experiences my way, no job is to difficult in my garage.
DanO

[Tbird100636]

The 1965 T-Bird 390 had a 600 cfm Autolite 4100 carburetor to begin with. It should have 1.12 stamped on the LF side of the body. Just rebuild the Autolite 4100. You won't have to modify the throttle rod, wire the choke, just drop it on, adjust it and you'll have a reliable performer.

[RedBird64]

Unless your going for a lot of other upgrades, I would stick with the Autolite.

Scott

[scumdog]

Well its 2 to 1 in favor of the Autolite.........................I personally would us one as an ash tray! The Holley even in a base model is a better carb then the Autolite.

Depends.

If you just want stock performance cruise-ability the Autolite is pretty good imho.

If you want to be able to adjust for perfomance....Holley

[ofairlane]

I am thinking about just rebuilding and if I am not happy I will drop in a Holley, I have the winter to rebuild and we'll see in the spring how it works, unless I get itchy fingers and a warm spell.

[ofairlane]

Long time between updates, I haven't played with the car much, anyway, bought and Edlebrock carb, swapped it and it runs soooooo gooooood now, the right move. Sorry guys

[redbow]

Yea!!! I keep telling people if they want a "Go Fast Carb" then use a Holley. The 4100 is one of the best ever carbs up to a point. But the Edlebrock is even better for just true pleasure of driving. It's sooooo programable and they don't leak all over your manifold.

[Krubba]

ofairlane, any chance you could share which edelbrock you went with? Any other engine modifications to get it running so good? Mines got a motorcraft 4300 on it, which isn't orig and I have no particular affinity for, but don't even know where to start if I were to start looking to replace...

[redbow]

I went with the Edelbrock 1406. That's a square bore 600 cfm with an electric choke. And it runs super "out of the box" with no performance mods. If I were you I'd go to Edelbrock.com and research it out. The 4300 is a Quadrajet look alike and I think is a spread bore. There were no other mods to my engine as far as I know. Except for what I did at that time, carb, plug wires points, cap, etc. Since then I've added the Pertronics, 100 amp alternator, Casco high flow water pump, wide opening thermostat and an aluminum radiator. My car has A/C and was running warmer than I liked in the Texas heat. The carb was purchased from O'Rieley's Auto Supply for about $275.00. Hope that helps.

Burke

[sseebart]

I run a 1406 as well, and it performs just fine. Cold starts are quick and warm starts are like most other carbureted cars--quick if the car has been off for only a few minute, takes a couple of turns when the engine has been allowed to sit a while.

Mine also ran great "out of the box." I adjusted the floats, but didn't need to change out jets or anything to get good performance on an otherwise stock engine.

My car is a daily driver, and I've had the carb on there for 2-3 years. Recently, it's developed an intermittent starting issue--very hard to start when warm on rare occasions. I suspect, though, that only a tune-up (or maybe a rebuild) is required.

~Steve

[JETBRD66]

Did you mod the air cleaner for the 1406 to fit ? or go with another kind of air cleaner

[redbow]

There were two tabs on the bottom of the original unit that were 1/2" long and 1/4" deep. Ground them flat and the unit fits as new.

Burke

[JETBRD66]

Thanks for the info.

[ofairlane]

Yes, mine is a 1406 with electric choke, the only modification I remember was the bolt for the air cleaner was not long enough, I had to find a longer bolt and cut the head off or something like that, no biggie. It ran smoothly right out of the box, I haven't played with anything at all on it, but it has been under snow for what seems like 6 months now !!!!!
I will follow this post up when I get it out and about in the springtime

[WerbyFord]

Ofair,
Good choice on the 1406 carb.
I tested 3 "Carterbrock" carbs, all the 600-625cfm model (Edel rates em at 600cfm, Carter at 625cfm) on the clock on a fairly stock FE.
The quickest of the 3, jetted box stock, was the 1406 carb. They are jetted lean for open headers and a cam, some folks complain about that, but for a stock 390 they are just about perfect as is.

Only thing is, in hot weather, they boil the gas out quicker as the body is aluminum. So in a few days of summer you come out and the carb is dry, all the gas boiled/evaporated. Kind of like a Holley except they pee it out all over the intake.

The fix for the Holley is, put it on for a weekend of racing, then take it off again, drain & box it. I do lots of carb shootouts, it is always one of my Holleys that wins by 1 or 2 carlengths (if that matters to you which it may not!!) But they leak a lot.

The fix for the Carterbrock is run a plastic/phenolic spacer. Unless you're in a REALLY cold climate you don't need that hot water spacer, we ditch those every time. That and a 180 thermostat will keep the carb cooler.

The 4100 Autolite is plenty of AIR, even though it has been measured at more like 500 cfm wet flow. Nobody knows where that 600 came from.
But that is about perfect for a 390. My rule for CFM is, "double your horsepower, then subtract 10%". So take the 390/300 at about 285 real gross HP, 285x2=570 - 10% = 513cfm so the 4100 is about perfect. They are still usually about a carlength slower than a good Holley but much less trouble. I've clocked bigger carbs on a stock 390, extra air doesn't do them any good.

I would keep your original carb (and always good to have a spare for testing!) but the 1406 is a good choice. They do like a fresh accelerator plunger so if it ever hesitates that may be the culprit.