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super six engine bog
https://slantsix.org/forum/viewtopic.php?t=11400		 Page 1 of 1
Author:  terryx [ Sun Jan 09, 2005 11:45 pm ]
Post subject:  super six engine bog
Ok so I have done the mighty super six conversion and dialed it in and set the timing, the valve lash, done the tune up, checked for vacuum leaks and it does work pretty well. More power and all that.

But the darn thing still has that anoying bog. enough to stall the engine if I floor it while going about 15- 20 mph.

So can anyone recommend what to do about this. I have tried enriching the carb until I'm blowing black smoke out of the tail pipe and that does not get rid of the bog.

I have heard that I can try different needles till it works? Which is one idea.

The other is to up the engine vacuum by re-building the head. my engine has always had a low vacuum. And in fact before the super six carb I had a bog on the one barrel holey. I cured this by upping the jetting to around a 60 size, but I think it was also a little too rich.

So I have been thinking of pulling the head, shaving 60 thou off it and re-grinding the valves to get the engine vacuum up.

Is this the right track ???

Any info appreciated :roll:
Author:  argentina-slantsixer [ Mon Jan 10, 2005 8:20 am ]
Post subject: 
dunno how shot is your head, but Ive had this bog in the past and it's always been related to either bad acceleration pump in te carb or retarded timing. also if your vacuum is consistently low, you may wanna look at valvle lashes, wich you already did. do you have a custom cam?

my 2 cents goes for the accel pump since you already checked evrything out.
Author:  terryx [ Mon Jan 10, 2005 9:43 am ]
Post subject:  super six engine bog
Just to add a little more info. My car is stock with only 50K original miles on the engine. The head is fine, the valves are all adjusted to 10 and 20 thou. Timing is around 8 advanced, any more and I get pinging going up hills. Point gop, plug gap all done and standard settings.

I don't think the head is bad, but the engine has always been on the low vacuum side around 15 at idle. It get good compression though 140-150

The accelerator pump is working on the carb, when I look down the bowl and pull the cable I see two jets of gas get squirted out.

But I still have that old bog . . . . .. :?:
Author:  textoad [ Mon Jan 10, 2005 11:23 am ]
Post subject: 
I just put a Holley 5200 on my car and it had a bad bog . I discovered the idle jet was a 100 (not sure what the actual hole diameter is) so I changed it to a 50 recommended by others who have used the Holley/Weber 32/36 and it cured the bog. My guess is the jetting may not be right. Are you using the Carter BBD? I have no idea how that carb works. Kust my 2 cents.

My car still doesn't have real god power though. I'm still dialing it in.
Author:  argentina-slantsixer [ Mon Jan 10, 2005 11:31 am ]
Post subject: 
what kinda ignition are U using?

if electronic, check reluctor gap with a bronze gage (0.08)

spark plugs gaps? maybe too open or close?

also I'd check the magnetic pickup resistence (may be shot?) or pints if you're using points distributer.

is te vacuum can correctly plugged to a ported vac port? is adjusted fine? is working? you may wanna lower the tension on the vc pod spring (3/32 allen wrench, clockwise softens, ccw hardens)
Author:  SlantSixDan [ Mon Jan 10, 2005 1:18 pm ]
Post subject: 
"Bog if accelerator pressed, stall or near-stall if accelerator stomped" is most frequently related to the carb's accelerator pump. If the engine runs well at cruise (i.e., after it bogs, it picks back up and runs strongly), then it is almost certainly related to the accelerator pump, especially if the bog occurs immediately as you press the pedal.

If the bog occurs a second or so after you press the accelerator, then the step-up system is suspect. What exactly did you use for a carburetor? Did you rebuild it, buy a remanufactured unit, just use it as-was...?

The Carter BBDs have a few service tricks that are sometimes necessary when rebuilding to make the accelerator pump work correctly. Tell us what you're starting with for a carb.

Just richening the carb with the idle needle(s) is not going to fix the problem and will cause the car to run poorly, guzzle gasoline, foul spark plugs and be a gross polluter. Same goes for rejetting: You almost certainly don't need to do it.
Author:  70valiant [ Mon Jan 10, 2005 3:22 pm ]
Post subject: 
1st check for vacuum leaks, then reduce your pump shot a little if no leaks found. Right now mine bogs because I detuned it a bit for winter driving. I backed off my timing, richened the mixture(for cold weather starting) and reduced my pump shot. the back end still gets a little squirrely at times but it is safer when ice could be hiding anywhere.
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