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What causes bog?
https://www.slantsix.org/forum/viewtopic.php?t=13015		 Page 1 of 1
Author:  lineberg50 [ Mon May 16, 2005 7:15 pm ]
Post subject:  What causes bog?
I was running my super six conversion tonight. This is a four speed overdrive trans D150. In 3rd at about 40 mph if I floor it, I get a bad stumble, flat spot, bog what ever it is called.

What can cause this.I haven't up graded my exhaust pipe off the manifold to 2 1/4" yet. Can that part of the reason. If I go easy on the throttle, she won't bog

Also, just for general info. I kept the original throttle cable from the one barrel. I looped it down oiled and greased it but had a binding problem (stuck open)at first. Tonight I fabricated a bracket and attached the throttle return springs from the one barrel to this and the new carb to assist closing the throttle. Its working so far
Author:  SlantSixDan [ Mon May 16, 2005 8:12 pm ]
Post subject:  Re: What causes bog?
Quote:
I was running my super six conversion tonight. This is a four speed overdrive trans D150. In 3rd at about 40 mph if I floor it, I get a bad stumble, flat spot, bog what ever it is called.
If you had a flat spot every time you floored the gas (from any speed, or starting off from a standing stop, etc.) I'd think your accelerator pump needed attention. It still might. With the engine off, remove the air cleaner lid and operate the throttle lever while looking down into the carb. You should see two good, strong shots of fuel ("Ssst!") squirt out of the inner sidewall of the carb throat. If they're piddly and weak, your accelerator pump needs attention.

But, since you don't mention any but a 40mph-and-step-on-it flat spot, it sounds more like your step-up rods maybe aren't stepping up quickly (or aren't stepping-up adequately, or they may be gunked up).

Tell us about this carburetor. What's it from, what've you done to it, etc.

Flat spots like this can also be caused by improper vacuum advance. What kind of ignition system are you running? With/without vacuum advance?
Quote:
I haven't up graded my exhaust pipe off the manifold to 2 1/4" yet. Can that part of the reason.
Naw.
Author:  lineberg50 [ Tue May 17, 2005 5:03 am ]
Post subject: 
I just put on a rebuilt Carter bbd that I bought from Advance auto.

The ignition is stock

Do you think the carb needs further adjustment?
Author:  lineberg50 [ Tue May 17, 2005 5:06 am ]
Post subject: 
I forgot to add the ignition has the Spark control computor so there is no vacuum advace pod on the distributor. That is my next plan of attack, an MSD 6 or Blaster and a dist with a vacuum advance.
Author:  Slant6Ram [ Tue May 17, 2005 6:51 am ]
Post subject:  Spark control computer?
Verify proper accelerator pump action before trying my tip

Here is what I found worked to end the bog with my car.

First, run the engine until it is warmed up and choke opens fully.

I you didn't have the spark control computer, I'd say to advance the timing and recurve the distributror. I don't suggest changing timing settings now will just hurt performance by throwing the computer out of time. If you have a timing light, I suggest you take a look at what happens (as far as timing advance) when you push the gas. Did you properly connect the timing advance port of the carb to the spark control computer?

This may work as a temporary measure while you prepare to correct your computer headache:

I needed to open the idle mixture screws about a turn and a half, and then reduce the idle speed screw back down to a normal idle. This gives the motor a richer idle, but bog is diminished greatly. Seems like this adjustment is directly proportional to gas mileage, so don't say I didn't warn you. Gas mileage sucks, but pulls like a scalded dog. I was able to close the idle mixture screws about 3/4 turn a few weeks later. I think I might have got a tank of particularly bad gas.

This is a bandaid, not a true repair.

My car has badly worn rings (I'm building a replacement) and poor compression. You could also be looking for vacuum leaks, and working out your computer ignition 'problem'.
Author:  lineberg50 [ Tue May 17, 2005 7:16 am ]
Post subject: 
Thanks, I'll check the vacuum lines to make sure and the carb accl pump and the timing.

Do you think I'll have less headaches if I pull the computor and go with an MSD ingnition and a standard vacuum advance distributor?
Author:  440_Magnum [ Tue May 17, 2005 8:05 am ]
Post subject: 
Quote:
Thanks, I'll check the vacuum lines to make sure and the carb accl pump and the timing.

Do you think I'll have less headaches if I pull the computor and go with an MSD ingnition and a standard vacuum advance distributor?
I think this is far more likely a fuel problem (lean spot) than an ignition problem, so start there.

Computer? What computer?? What year truck is this? Is this a lean-burn setup with a feedback-controlled carb? By the fact that you're putting on a super-six setup, I'd assumed that it wasn't. If it is a computer-controlled lean-burn, that changes things a lot.
Author:  SlantSixDan [ Tue May 17, 2005 8:30 am ]
Post subject: 
Quote:
Do you think I'll have less headaches if I pull the computor and go with an MSD ingnition and a standard vacuum advance distributor?
My preference is to get rid of the ESA computer and go to the standard vacuum advance distributor, yes. They are much more versatile and tunable than the ESA setup, which has ONE spark advance curve, and if you don't like it, tough.

MSDs are good ignitions, to be sure, but they're spendy and they're not the only good ignitions. the HEI conversion is easy, better than using the Mopar module, reliable, allows bigger spark plug gaps, and eliminates the ballast resistor. Or (shameless self-promotion mode ON) since you hafta buy a distributor anyhow, you could always buy my brand new Mallory UniLite! :-D
Author:  lineberg50 [ Tue May 17, 2005 10:06 am ]
Post subject: 
Tell me more about this malloy unilite. All I have to do is set it in and hook to the coil and resistor no other control box is needed?
Author:  Rust collector [ Tue May 17, 2005 10:11 am ]
Post subject: 
Yup! 8)
Author:  lineberg50 [ Tue May 17, 2005 10:28 am ]
Post subject: 
So I can yank the esa and get rid of all the little hard plastic vacuum lines?

Any problems found with this type of dist set up?
Author:  Rust collector [ Tue May 17, 2005 10:35 am ]
Post subject: 
Quote:
So I can yank the esa and get rid of all the little hard plastic vacuum lines?
Yup!
Quote:
Any problems found with this type of dist set up?
I have not heard anything special about problems with them...
I guess it is almost like the gm. HEI system.
All the stuff inside the distributor.
Author:  lineberg50 [ Tue May 17, 2005 11:02 am ]
Post subject: 
OK Slantsixdan, Watch the news. You may see an article titled "Man beaten senseless by wife with Mallory Unilite dist" because I just bought yours. Thanks...Jim
Author:  SlantSixDan [ Tue May 17, 2005 11:22 am ]
Post subject: 
Looks like it! Don't think I've ever had a listing end quite that quickly after it was posted. I've left you positive feedback and your distributor will go out today or tomorrow.

If I had the setup/instruction sheets, I'd include them, but I don't. I am certain Mallory can still provide the info, though.
Author:  lineberg50 [ Tue May 17, 2005 11:55 am ]
Post subject: 
No problem, I just downloaded the installation instructions from their website.
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