I have a 72 F250 with a 390 motor edelbrock intake and 4 barrel carb I recently picked it up I had to use for the last week to commute in and I have some backfiring cliombing hills and when I want to hammer down the pedal It boggs horribly feels as if too much fuel or fuel starve can't tell I am trying to decide the method of attack I want to begin with new lines and maybe an electric pump.. Where is the best spot to mount and do I eliminate the canister style mechanical pump altogeather? I also need some info on a fuel pressure regulator is 1-4 psi enough??? Am I on the right track? I also have been reading on site about the accelerator pump Is this part internal in the carb can it be changed out? THANKS

 

I would first check the timing. Yes, if you remove the top, you can change the pump assembly.

 

I have an old timing light however I have never used one . Is ther a post explaining the proper use? THANKS

 

Typically backfiring or low power pulling hills is a fuel starvation problem. Could be as simple as a plugged fuel filter or collapsing fuel hose, defective fuel pump. The electric pump should go as close to the tank as possible to stop vapor lock. PSI should be about 3 to 5 pounds - this will effect the fuel level in the carb. More PSI=higher fuel level. Do not pump through the old mechanical pump - if the diaphragm leaks you could fill the crankcase with fuel or spray fuel out the breather hole. Accelerator pump should squirt two jets of fuel at the slightest movement of the throttle. Bad plug wires can also cause your problem They should have about 10,000 ohms per foot of length. At night you should see no spark jumping from the wires (in the dark or low light). Glazed plugs can also cause your symptoms. It is tough to t-shoot by mail.

Timing light - Pull the vacuum advance hose off and plug it. Hook up the trigger lead of the timing light to plug # 1 (passenger side closest to the radiator). Hook up power leads to the battery. Find the timing marks on the damper and timing cover and clean them off. Use paint, white out or chalk to make the marks visible. Start the engine and idle no higher than 600 - 650 rpm. Check timing at idle should be 4-10 btdc( better check the manual I am too old to remember this). Slowly rev the engine to 2500 rpm and watch the timing marks. It should steadily advance indicating the mechanical advance weights and plate are working.

Hope this helps ya,

Scucci

 

Since it has been a long time since I worked on carbs I hope you don't mind if I ask.

Is timing the best way to go. I am having the same trouble with my 74 360. I have a edelbrock 4bbl carb and when I hit the gas and let off the engine stops running. I thought it was the timing but have not gotten that far. I did notice that there is a strong gas smell when the engine shuts off.

Any suggestions or is it still the right track to check timing first?
(Sorry if its confusing)

 

Timing is an easy check and will help eliminate one piece of the puzzle. Normally plugs, wires and timing are part of a tune up. There is also the possibility of a vacuum leak on both vehicles. Edelbrock carbs are built on the old Carter AFB series. A simple carb to work on. The metering pistons/pins may also be sticking causing the stall ( sticking in the up position) or bog (sticking in the down position). It might be good to check the timing, the fuel pressure, manifiold vacuum, plug wire resistance (10,000 ohm per foot maximum) and vacuum advance units on these vehicles to get an idea of overall engine condition. If the carbs have been sitting for a while it might be prudent to put a kit in them.
Hope this helps
Scucci

 

I fixed my problem mostly by switching to an electric pump and then I timed it runs alot better It's good to rule out fuel issues by putting in an electric you know you got fuel now. The next step is to change out the wires and plugs.

 

Sounds like either your idle speed is too low or perhaps your float levels are a bit too high.