Hello to all!

Im new hear to this site and I have a few questions. I recently bought a 79 F-250 Supercab 4x4. It has a stock 429 in it with a 1406 Edelbrock and Im having a hard time getting it to run good. It fires right up even when its cold. The problem is when I go to drive it there is a hesitation when you first step on the pedal. You have to feather it to keep it running. The next problem is when I try and set the idle mixture screws, I can turn the screw on the drivers side all the way in and it does not effect the engine at all. I heard it could be a vacuum leak so I sprayed carb cleaner around the base of the carb and found nothing. I then sprayed a little into the primarys of the carb and there was still no change. Im not sure if its running to lean or to rich. When I ask someone what they think everyone says it probably running to lean. But from the smell of it running I would say its running rich. Also the carb has been rebuilt recently and everything was set back to the stock settings. I live in Colorado where the air is a little thinner. Let me know if anyone has any ideas where i can start.

 

I run the same carb on my 390. I also live in CO. I had to swap jets but considering your extra displacement my set up wouldn't apply to you. If you are squirting carb cleaner directly into the bores and not getting a change in engine sound you definitely have a vacuum leak somewhere. Be sure to check the seal between the intake/head and the vacuum tree. Also make sure you have your dist advance to the timed vacuum and not the constant vacuum port on the carb.

 

Sometimes it's hard for the "spray test" to find anything unless you lean the engine out so far that it barely runs. Other places to check for a vacuum leak include dry-rotted vacuum hoses and the power brake bookster (if equipped).

 

Its sounds like your running lean, and you need to adjust your metering rods.

You may also need a smaller set of metering rods, and an instruction manual.

 

I think I would disagree with the lean condition, sounds to me like it might be rich. Problem is if he has a vacuum leak its all germain because you can't tune or diagnose carb set up with a vacuum leak

 

Lean carbs will give hesitation.

Rich carbs will tend to bog.

He could have a faulty enrichment circuit. I forget hot Edelbrock does it.

 

Again though, if he can adjust the mixture screws and gets no change on engine performance its impossible to tell. The hesitation is not from the carb set up, and therefore cannot be used to diagnose rich vs. lean condition. The carb is 600 cfm for an Edelbrock 1406 model. I would suggest to the owner, when you fix the vacuum leak put clean plugs in and run it for a bit. That will confirm your carb settings.

 

He may only be adjusting the idle screws.

He needs to get an Edelbrock book, and do some studying.

He said he tested for vacume leaks already.

 

The edlebrock has two mixture screws on the front of the carb. The only other adjustment is the idle set screw on the throttle linkage, and the high idle set screw on the choke linkage. Edelbrocks are insanely simple, two screws in front, cw lean ccw rich.

kdawg, have you hooked a vacuum gauge up to actually check for a leak or have you just been doing the spray test? Next step is def a gauge.

 

Well it was definetly running lean. It didnt take long to realize it once I took it on the interstate. I rejetted it and now it does not hesitate on exceleration. The drivers side air mixture screw was plugged. I also did a vacuum check with a gauge and everything checked out ok. The only problem that I am having now is that when its ideling it still smells like its running rich.

 

Had that same problem for years! Would get it perfect only to go to pot asap. The carb is just junk. The best advice is to go with a Holley. That is what I was told and many yeary later; to many waisted days mind you I got one. Steet advenger. Best swap to day and I have done a lot of swaping on the gal. Just my two cents worth.

 

Edelbrock's manual for the 1406 is available online.

 

Check all vacuum lines big or small for hardening, cracking etc. they are made of rubber therefore should be rubbery. Replace as needed and check the canister as well for punctures etc. GET A GAUGE! It makes life much easier.

 

I disagree and many more will as well.

The Performer (or Carter AFB) is a perfect example of a "set it and forget it" carburetor. Once it is adjusted and tuned it will remain faithfull for a long time.

The Holley style carb constantly needs attention. And whoever thought having the fuel bowls with a vertical gasket seam was a good idea is a complete moron. Don't have fuel leakage problems with an AFB.

I will without a doubt recommend a Holley for a performance- minded racer, it can't be beat HP to HP. But the AFB gets the job done without all the fuss.

Josh

 

BS, most are junk. Like I said if you get a good one yes or you run a 650. The 750's are junk. Owned one for years listening to that crap. Switched and have yet to have the headache you say I will. If I do it is already less than the Edelbrock. That all I will say as you will never never change my mind on this one.