[frbird400]

Anyone running these carbs experience a vacuum leak at this hole? (see attached image) I understand the electric choke housing receives manifold vacuum to operate the pull-off. Is this a controlled leak during warm-up or have I lost a seal somewhere?

[PITTSBURGH 64]

I'd just remove the choke all together and block that port....... It's not needed, especially in Nevada...................

[frbird400]

Believe it or not, it does get down into the sixties here, damn near freezing!

Actually, its already in the triple digits. I think we skipped spring this year and went right to summer.

I'm actually removing the choke now. It's the 1406 model that came w/ the elec choke so I'm just trying to figure out what needs to be removed/retained.

[Cliff R]

Here, if one of them finds it's way into our shop, we remove the electric choke, and throw the carburetor away!

Seriously, any manifold vacuum leak pulls unfiltered air into the engine. This is never a good thing, especially in dusty/dirty conditions......Cliff

[Schurkey]

First Guess: That hole is the result of needing to drill a passage through the casting that intersected with another drilled passage. The open hole should have been sealed with a lead ball or somesuch when the drilling operation was done.

Second Guess: You don't have proper vacuum to the pulloff piston because of the vacuum leak.

Third Guess: the choke doesn't work properly because the pulloff piston doesn't receive enough vacuum.

[61-63]

I don't know about the Edelbrock but on the original AFB the carburetor body has a very small vacuum port at that location which was used to pull heated air from the intake manifold
or exhaust manifold up the through the thermostatic choke and into the carburetor, which insured that the heat actuated spring in the choke got heat and hence the choke opened up as the engine warmed up. On an electric choke carburetor that port is not needed. Take the choke body off the carb and look at the carb body in that area, and if there is a small hole put a dab of JB Weld in it. Then put the choke back on and go.

People are always lambasting Edelbrock carbs on this site and they are good carbs I don't care what anyone says. Someone needs to go down through the pits at Norwalk and tell all of the people running awsome times with their Edelbrocks that they really aren't running those times.

[rcread]

I replaced my E carb with a Q-Jet built by Cliff, but when I had the Edelbrock, my electric choke was pulling vacuum through that same hole. I plugged it to no ill effect.

I don't know if my Edelbrock carb was typical, but its problem wasn't full throttle. It was part throttle transitions on the street, which would result in the car jerking back and forth. Not really what I want in a mostly street car. The Quadrajet is worlds better.

[Cliff R]

"People are always lambasting Edelbrock carbs on this site and they are good carbs I don't care what anyone says. Someone needs to go down through the pits at Norwalk and tell all of the people running awsome times with their Edelbrocks that they really aren't running those times."


I've spent a lot of time in the pits at Norwalk, and scores of other tracks, big events, etc, and it's rare, and I mean extremely rare to see a street car running anywhere near where we are with an Edelbrock AFB clone. Butloads of 14 second and slower cars using them, at nearly every track we run at.

When I have some guy fly by me like I'm sitting still using one, I may take notice!

Anyhow, they are to date the WORST carbs I ever tested. Didn't say that they weren't any good. They have several design flaws built into them, and the BIG showstopper is the lack of any adjustment for the opening rate of the secondary airflap.

High HP to weight ratio cars, like my own, are unable to use one in any configuration, as any quick full throttle movement and the engine "pukes" all over itself.

The slower the vehicle speed and engine rpm, the worse the stumble.

Once past the HUGE stumble, they pull as hard as anything else out there right to the shift point.

Relatively easy to tune, and they work 100 times better once you put a good accellerator pump in them and the correct springs. In stock form, as mentioned above, the worst carbs we ever carried to the dyno/dragstrip.

We have also tested the AVS version, which is LIGHT YEARS better than the AFB clones, but they are still big, wide, ugly and often difficult to use with stock Ram Air and Shaker assemblies. Since they offer no advantage anywhere over a correctly tuned q-jet, we don't use or recomend them.....Cliff

[frbird400]

Thanks for the info. I just removed the choke and plugged it. I've always used holley carbs in the past, this car just came w/ the edelbrock when I bought it so I figured I'd do what I can w/ it.

[blown 68]

i am running two carter 625's, one choked, i have the same 'vacuum leak' you describe, and when i plugged it, i did have adverse affects. it would surge during warmup, (blown motor, i like the choke, i don't like holding the peddle down to warm up, why waste time.....), and once i unplugged it, it ran fine. i looked in there, the best i can guess, is it's blow by, or 'suck by' on the little piston in there. without allowing 'unequalization' of vacuum between the backside of piston and atmosphere, it had problems......

for now, i run it unplugged. i may just put a barb in there, and run it into the aircleaner base.......

i did see an old afb choke, and it had a fitting in there running to something i presume........

i agree with both sides of the arguement. i would not run one in a single carb application, i would go quadrajet. but, running duals, i love them. i have an a/f meter, and i dialed mine in perfect. my mid 240's intake, high 250's exhaust duration roller cam, with a 114 lobe sep, idles at 650 rpm's all day. crisp throttle, no bog, perfect. but, i get cliff's side perfectly on a single carb setup, they are not 'tuneable' enough to run them well...........


davey

[Bob Arthur]

Cliff,
I am running a 1406 on a basically stock 66 Goat and I am quite happy with it. I only cruise so I don't need scads of power but a little extra won't hurt. I richened it up with smaller diameter rods and stock jets. You mention accelerator pump and springs. Could you elaborate?

[Evil Stu]

Bob,

I have a 400/THM400 in a 70 GTO. I just replaced my E 1406 with a QJet. I went through the carb myself using a kit from Cliff and his book. The 1406 never gave me a real problem, always ran OK (street car, no strip) With the QJet everything is better, noticeably better power, idles nicely, pulling away from a stop much nicer and smoother; the car is just better.

Stu

[Cliff R]

You mention accelerator pump and springs. Could you elaborate?

I try to stay away from the E-clones, but have been forced to work on a few of them. We noticed that they use the same spring under the accellerator pump as is found on the pump. It's kind of difficult to get the pump to work correctly if both springs are the same. This means that initial pump shot will be poor, if not non-existant all together. Then as the pump spring compresses, it will eventually overcome the spring under it, and deliver fuel to the engine.

We ran into this problem recently with a Marine AFB clone. Completely rebuilt it with a complete kit, and it stumbled and hesitated pretty badly. I had it apart a couple of times, and the pump was not damaged in any way, it just didn't work well. I bought a complete pump assembly with upgraded springs, and it completely corrected the issues with the carburetor......Cliff