Edelbrock Carb Guys??

[Gidge768]

Hello CB,

I just rebuilt my Edelbrock #1405 and switched the manual choke out for an electric. Bronco starts right up and idles great. Once you pump the gas peddle it like it wants to choke itself out. Sometimes it will even backfire through the Carb. When I put it all back together I added a fuel filter, pressure gauge and Pressure regulator. The gauge shows around 4 psi right now. I believe the back fire is to much fuel cause if you have the air filter off you get a nice Fireball....lol

The Bronco has always had a little something wrong with the way it runs so Im trying to get straitened out. Also, Does anyone know where to start with the Timing?

I believe the motor has a mild cam, edelbrock intake and carb. It also had a headers and full exhaust if that matters.

Thanks for all the help,
Sean

 

[tatersalad]

assuming the engine is a 302 or 351 set the initial timing to 10 degrees. To set the carb attach a vacuum gauge to a full vacuum port on the carb, turn in the idle/air screws on the front of the carb until all the way in or it starts to stumble then slowly bring them back out (one at a time) watch the vacuum gauge until you get the most vacuum,repeat on the other idle/air screw and then adjust slightly to see if you can get anymore vacuum out of it. If the vacuum gauge is jumping all over the place you have a vacuum leak somewhere most likely.

 

[Gidge768]

Its a 302, sorry. When you say bring the air fuel screws in all the way that would be turning them to the right to tighten correct? For a full vacuum port I think the only one not being used is in the front. a small one on the drivers side. Does that make sense? I think the small one on the passenger side is being used for my vacuum timing advance and the big one in the rear goes to my brake booster.

 

[Terkish]

I always have issue when tuning my carb. Read through this. It helps me out a lot with edelbrock tuning. Page 11 is the idle tune section.

http://www.edelbrock.com/automotive_new/misc/tech_center/install/1000/1406_manual.pdf

 

[dave67fd]

Listen to tatersalad. One of the best and easiest ways to get the carb set. You may have to up the idle screw on the linkage to keep it running. Once the procedure has been done readjust idle screw for the proper idle.

 

[BoltBuster]

.........watch the vacuum gauge until you get the most vacuum,repeat on the other idle/air screw and then adjust slightly to see if you can get anymore vacuum out of it. If the vacuum gauge is jumping all over the place you have a vacuum leak somewhere most likely

tater, are you placing the vacuum gauge on the vac tree or on the carb plate vac tube?

 

[broncnaz]

Doesnt matter where you hook the vacuum gauge up as long as it has full vacuum at idle.
While it is good to get the idle adjuted correctly I dont think the idle circuit has anything to do with your backfiring. Still your looking for the highest steady vacuum. you may need to readjust both timing and the carb several times to attain the best idle.
Timing is different for every engine but 8-12 is a good area to start. You just have to find out what works best for your engine.
For most carb adjustments you need to make sure the engine is fully warmed up. Id also make sure your whole ignition system is in good shape. Maybe do a complete tune up.

Backfires thru the carb are usually caused by being being to lean or having to much timing advance. The lean condition could be from a vacuum leak or that the carb is jetted to lean or the accelerator pump circuit is either not working or not pushing enough fuel to cover the lean condition when the throttle blades are opened.
There are other issues that can cause it but I wont go into that now you need to see if the adjustments help at all.

 

[El Kabong]

Also double check your firing order against the spark plug wires, especially if you have had them off recently. Crossed wires will cause backfiring too.

 

[tatersalad]

If I remember right, the 1405 has two vacuum ports on the front of the carb. one is metered and the other is full vacuum. I believe the drivers side was the full vacuum side. if your gauge is all over the place then you probably have a vacuum leak. If you haven't already done so I would recommend installing there off road kit, it is two spring loaded fuel bowl (jets?) and instructions to reset the float lower.

 

[PaveBronco]

There should also be a manifold vacuum port on the back side of the intake. Your accelerator pump linkage might need to be moved up a hole to reduce the stroke; I think the initial is the middle? I just re-read the post, you just rebuilt it, did it do the same before you worked on it….not saying….just asking…. I also would look at timing, firing order..Dizzy position, may be a tooth off..
I ran an Edelbrock for years and just couldn’t get it to work well off road even with the off road kit and an adjustable pressure regulator. I did like the adjustability with is great for changes in altitude in the mountains. I sh!t canned it for a Holly which works great with off road needle and seats and extended fuel vents.

 

[tatersalad]

I ran one for years also with the off road kit. the kit helped a lot but it still wanted to load up in the hills. bosch platinum four plugs helped out with loading up too.

 

[Gidge768]

Did some vacuum tuning today. I have the motor idling at just over 15 psi at vacuum and around 4 psi at the fuel regulator. After calling Edelbrock the tech told me to look at the primarys and give it gas. There was no fuel being dumped at that time. Took the top of the carb off and noticed I must have put the blue gasket in the wrong spot on the accelerator pump so it wasent holding pressure and squirting fuel. Once placed in the wright spot and I put the carb back together. Now she seems to be running smooth and mint. Hopefully if the rain stops tomorrow I can take her out and she how she feels.
Thanks again for all the help everyone.