Part throttle bog

[69SKCharger]

Just rebuilt the carb on my Charger (383), and also changed the intake manifold gasket to block the exhaust cross-over, hoping to eliminate my vapor lock issues. For the carb, it's an Edelbrock 650 AVS and I used the Edelbrock kit, following the instructions word by word. Getting the car back on the road this spring, timing set, idle air mixture screws set, everything seems great at idle, but getting into the first ~10% of the throttle, it bogs badly - no power. I changed the step up springs in the cab to the pink ones and moved to the closest hole on the accelerator pump, and that seemed to help a little, but the problem still exists. However, here's the strange part - after driving for a good amount of time, well past when the engine has reached operating temp, it starts running normally - no more bog. It does this consistently. The only thing I can think of is that my coil is going bad, does that make sense? Other suggestions?

 

[AR67GTX]

Try setting the accelerator pump a little higher by bending the rod. I had a problem with an Edelbrock once where the “v” in the accelerator pump well seemed to be too high and at stock pump height it was not uncovering the “v” to let the well to fill - resulting in a bad bog off idle for anything but the slowest throttle opening. Some forms of Carters don’t use the “v” fill method however.

EDIT: not awake yet. Set the pump height “higher”, not lower. Jezzz, where’s the coffee?

 

[wagonman]

Well you blocked the intake cross over and that is used for cold driveability. I see you are up north what are your temps now? Running a choke?

 

[Rusty knuckles]

I think you need to change your metering rods to richen it up more. Possibly jets too. There are cheap kits available.

I say this because you're compensating the lean issue by going to bigger step up spring to get into the secondary circuit of the rods. You will probably need to put the metering spring back to what it was when you make the change.

My basically stock 383 with a 750 edelbrock needed fatter than out of the box tuning to work too.

 

[69SKCharger]

Well you blocked the intake cross over and that is used for cold driveability. I see you are up north what are your temps now? Running a choke?

I only drive it when the weather is nice ~20 degrees C or more. I have a manual choke and keep it on for the first several minutes of driving.

 

[69SKCharger]

Try setting the accelerator pump a little higher by bending the rod. I had a problem with an Edelbrock once where the “v” in the accelerator pump well seemed to be too high and at stock pump height it was not uncovering the “v” to let the well to fill - resulting in a bad bog off idle for anything but the slowest throttle opening. Some forms of Carters don’t use the “v” fill method however.

EDIT: not awake yet. Set the pump height “higher”, not lower. Jezzz, where’s the coffee?

That's a good suggestion. When I rebuilt the carb, based on the instructions, I did lower the height of accelerator pump and thought it was strange that it was set so high from the factory (it's not a very old carb). I'll try straightening that rod out a bit to be more like what it was.

 

[Geoff 2]

It sounds like leanness. Totally blocking off the xover was probably not a good idea, because some heat is needed to vapourise the fuel. Factory iron intake would be worse than alum. Whatever you used to block off the xovers, I would drill a 5/8" hole in each so that you get some heat.

 

[69SKCharger]

I tried raising the accelerator pump, relooked at timing and pulled the idle Air screws out a bit. Still no difference. Maybe blocking the exhaust cross over was a bad idea?

 

[1967coronet]

Once the engine is up to temp the cross over is a non issue.
You mentioned the spring swap.
Did you take a vacuum reading at operating temp ?
Set your carb air with the vacuum gauge and select your springs.
Read your plugs for jet and rod swaps.
Many times a lean engine smells gassy and exhibits the bad performance of rich condition.
Prob covered ... above but ck. Your fuel pressure and stay at 6 or a bit under.
Bad coil most times shows up when hot.

 

[69SKCharger]

Once the engine is up to temp the cross over is a non issue.
You mentioned the spring swap.
Did you take a vacuum reading at operating temp ?
Set your carb air with the vacuum gauge and select your springs.
Read your plugs for jet and rod swaps.
Many times a lean engine smells gassy and exhibits the bad performance of rich condition.
Prob covered ... above but ck. Your fuel pressure and stay at 6 or a bit under.
Bad coil most times shows up when hot.

I did, vacuum at temp is about 17 and I have pink springs in it which are rated for 7, so probably could go up one more to the natural spring at 8. Also used the vacuum gauge to set the idle mixture. Considering that it does eventually start running good, I think this might all be a product of blocking the crossover. It's taking a very long time for the intake to warm up and during that time, I've got a lean condition. I wonder if I can drill a hole in the gasket to just restrict the flow of exhaust gases, or if that will lead to it burning away.

 

[1967coronet]

If this bog is just a cool / cold engine temp give it a little more choke.
At normal temp that avs sounds like it is adjusted ok ( door spring ect ).
Like already mentioned mabey a bit more pump shot.
Oh, one more thought , your rebuild kit..... blue plunger cup ?? If it is swap it for the red one. Lots of guys have trouble with the blue cups.

 

[69SKCharger]

If this bog is just a cool / cold engine temp give it a little more choke.
At normal temp that avs sounds like it is adjusted ok ( door spring ect ).
Like already mentioned mabey a bit more pump shot.
Oh, one more thought , your rebuild kit..... blue plunger cup ?? If it is swap it for the red one. Lots of guys have trouble with the blue cups.

I believe it was a blue cup. The car had a red one in it.

 

[joe smith]

Take it back apart and double check your float height..... Not sure why gremlins change this after you install it...... SUPER critical and often a " hurried " part of a rebuild

 

[69SKCharger]

Take it back apart and double check your float height..... Not sure why gremlins change this after you install it...... SUPER critical and often a " hurried " part a of a rebuild

Sounds good. I'll do that when i switch back to the red cup for the pump.

 

[dvw]

On my racecar I always ran the float level higher than recomended. As i remember 7/16" is the stock setting. I ran them at 9/32". It starts the main circuit earlier.
Doug

 

[BSB67]

It is too lean until you have full heat soak. Simply try opening the idle mixture screws.