bog

Alan Roehrich · 05-22-2010, 11:42 AM

Bill, has it always done this, or is this a new problem?

You might try changing your two step RPM up or down in 200 RPM increments.

The problem you describe doesn't really sound like a loose stator shaft.

It sounds like the converter MAY be about 200 RPM or so too tight.

You might also try tightening the secondary air door an 1/8 turn.

There is a small baffle that attaches to the top of a QJet, on the two screws behind the choke horn. If you do not have one, you might want to get one and try it.

You might try a little more timing on the starting line.

Ultimate Converter Concepts · 05-22-2010, 11:51 AM

Quote:

Originally Posted by alan roehrich

bill, has it always done this, or is this a new problem?

You might try changing your two step rpm up or down in 200 rpm increments.

The problem you describe doesn't really sound like a loose stator shaft.

It sounds like the converter may be about 200 rpm or so too tight.

You might also try tightening the secondary air door an 1/8 turn.

There is a small baffle that attaches to the top of a qjet, on the two screws behind the choke horn. If you do not have one, you might want to get one and try it.

You might try a little more timing on the starting line.

x2

Rich Biebel · 05-22-2010, 08:38 PM

A Q-jet problem....I'd bet on it.....

I sorted thru 3 carbs and had one that worked perfect......The other two gave me problems off the line no matter what I tried.....and I tried a lot of adjustments....

A Hedworth carb did not work for me unless the engine was cold.... once it was warm it did exactly as you described.....I bought one and hoped it would cure my issues and it did not......Driving the car off the footbrake was very difficult with the way the secondaries tipped in....

I got one from another racer that worked very well and was easy to stage and race with.......

Woodro Josey · 05-24-2010, 10:29 AM

Bill, i would bet it is a Quadrajet problem. Getting them to work perfect with a 2 step can be a pain in the but sometimes.

Chad Mahlosky · 05-24-2010, 08:29 PM

Ironically, I run the same combination, in a GSA Nova. I bought a new fuel pump, and relocated it. I also went with new fuel cell, upgraded from hard 3/8 aluminum line to 1/2 in braided, changed fuel pressures, carbs, all the same stuff you mention. My car did it off of footbrake, and worse when I two-stepped the car. Still to this day, the car doesn't always act right, especially in good, cool air. No matter the combination that I try, my car will only run if its really, really lean. I mean like shouldn't even run its so lean. But, if you fatten up the carb at all, it absolutely falls on its face. I eventually got the problem somewhat cured, by putting the rods back into the front of the carb. This definitely got my car to leave on the two step. But please, someone tell me what to do, or why my car can not be fattened up and run?

Tony Curcio · 05-25-2010, 08:36 PM

I had similar issues when I first put a good engine in our H/SA Camaro. It had been fine with our home-built 11.80 engine, but would practically shut off when the front wheels got airborne with the new power. We tried two professionally prepared carbs, borrowed a known working carb, three fuel pumps, two regulators, pressure up, pressure down, float level up and down, and on and on. We could make it consistent with extreme jetting, but it wasn't nearly as fast as it should have been.

One day I unbolted the fuel pump while the fuel lines were still on. As it dropped downward, I heard fluid moving when gravity took over. It was like in the cartoons, when a lightbulb appears over the character's head.

I re-mounted the pump a lot lower. The pump inlet is now three inches below the the fuel cell outlet, and the pump body is visible under the rear valance. The inlet had previously been about an inch below the cell. Picked up 3+ tenths the next weekend.
Don't know if the same thing will work for Bill or Chad, but it costs nothing to try.

brett3533 · 05-26-2010, 03:59 PM

q/jet carbs are very finicky its important to have enough fuel pressure to the regulator to keep the fuel going forward on launch and not to much that your regulator can`t control the pressure from the pump. if it can`t the regulator may bounce or pulse allowing fuel to slowly blow by the needle and seat causing richness for launch making you lean down. I am having similar symptons also w/different combo. hope this helps. magnafuel is the best regulator on market for high pressure pumps. wade owens got my attention from his previous post about moving down his fuel pressure.

Robert Simpson · 05-27-2010, 06:02 AM

Tony you have a PM.

Quote:

Originally Posted by Tony Curcio

I had similar issues when I first put a good engine in our H/SA Camaro. It had been fine with our home-built 11.80 engine, but would practically shut off when the front wheels got airborne with the new power. We tried two professionally prepared carbs, borrowed a known working carb, three fuel pumps, two regulators, pressure up, pressure down, float level up and down, and on and on. We could make it consistent with extreme jetting, but it wasn't nearly as fast as it should have been.

One day I unbolted the fuel pump while the fuel lines were still on. As it dropped downward, I heard fluid moving when gravity took over. It was like in the cartoons, when a lightbulb appears over the character's head.

I re-mounted the pump a lot lower. The pump inlet is now three inches below the the fuel cell outlet, and the pump body is visible under the rear valance. The inlet had previously been about an inch below the cell. Picked up 3+ tenths the next weekend.
Don't know if the same thing will work for Bill or Chad, but it costs nothing to try.

SS 230 · 07-31-2010, 06:51 PM

bill, did you fix your problem,if so what was it?

Dean Oliver · 05-26-2010, 08:20 PM

Assuming the tune up is at least close (and I can't emphasize that point enough), the main causes of a Q-jet bog typically are related to:
- Too much fuel pressure. Do not depend on one of the little small online gauges for this. Double check your gauge with a second gauge.
- Air valve tension too loose. Keep in mind that adjustments should be made in small increments, like 1/8 turn at a time.
- Weak fuel system. Simple test. See how long it takes your fuel system to fill a one gallon container. Most SBC stockers with a Q-jet should flow a gallon in no more than 30 seconds through the entire fuel system, regulator and all.
- Improperly sized needle/seat (too big or too small) and/or improper float adjustment.

This is not an all inclusive list, but it is some of the more common things. A problem that I see too often is that a racer will just assume these things are good rather than take the time to actually check. Hope this helps. Give me a call if you want to talk more about it Bill.

Dean

05-22-2010, 11:42 AM	#1
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,066 Likes: 1,487 Liked 1,630 Times in 378 Posts	Re: bog Bill, has it always done this, or is this a new problem? You might try changing your two step RPM up or down in 200 RPM increments. The problem you describe doesn't really sound like a loose stator shaft. It sounds like the converter MAY be about 200 RPM or so too tight. You might also try tightening the secondary air door an 1/8 turn. There is a small baffle that attaches to the top of a QJet, on the two screws behind the choke horn. If you do not have one, you might want to get one and try it. You might try a little more timing on the starting line. __________________ Alan Roehrich 212A G/S

05-22-2010, 08:38 PM	#3
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,312 Likes: 25 Liked 543 Times in 212 Posts	Re: bog A Q-jet problem....I'd bet on it..... I sorted thru 3 carbs and had one that worked perfect......The other two gave me problems off the line no matter what I tried.....and I tried a lot of adjustments.... A Hedworth carb did not work for me unless the engine was cold.... once it was warm it did exactly as you described.....I bought one and hoped it would cure my issues and it did not......Driving the car off the footbrake was very difficult with the way the secondaries tipped in.... I got one from another racer that worked very well and was easy to stage and race with....... __________________ Rich Biebel S/C 1479 Stock 147R

05-24-2010, 10:29 AM	#4
Woodro Josey Senior Member Join Date: Jul 2007 Posts: 805 Likes: 0 Liked 3 Times in 1 Post	Re: bog Bill, i would bet it is a Quadrajet problem. Getting them to work perfect with a 2 step can be a pain in the but sometimes. __________________ Woodro Josey 2002 STK

05-24-2010, 08:29 PM	#5
Chad Mahlosky Junior Member Join Date: Jun 2006 Posts: 83 Likes: 0 Liked 7 Times in 2 Posts	Re: bog Ironically, I run the same combination, in a GSA Nova. I bought a new fuel pump, and relocated it. I also went with new fuel cell, upgraded from hard 3/8 aluminum line to 1/2 in braided, changed fuel pressures, carbs, all the same stuff you mention. My car did it off of footbrake, and worse when I two-stepped the car. Still to this day, the car doesn't always act right, especially in good, cool air. No matter the combination that I try, my car will only run if its really, really lean. I mean like shouldn't even run its so lean. But, if you fatten up the carb at all, it absolutely falls on its face. I eventually got the problem somewhat cured, by putting the rods back into the front of the carb. This definitely got my car to leave on the two step. But please, someone tell me what to do, or why my car can not be fattened up and run? __________________ Chad Mahlosky 3225 STK

05-25-2010, 08:36 PM	#6
Tony Curcio Member Join Date: Mar 2002 Location: West Chester, PA Posts: 271 Likes: 1 Liked 4 Times in 1 Post	Re: bog I had similar issues when I first put a good engine in our H/SA Camaro. It had been fine with our home-built 11.80 engine, but would practically shut off when the front wheels got airborne with the new power. We tried two professionally prepared carbs, borrowed a known working carb, three fuel pumps, two regulators, pressure up, pressure down, float level up and down, and on and on. We could make it consistent with extreme jetting, but it wasn't nearly as fast as it should have been. One day I unbolted the fuel pump while the fuel lines were still on. As it dropped downward, I heard fluid moving when gravity took over. It was like in the cartoons, when a lightbulb appears over the character's head. I re-mounted the pump a lot lower. The pump inlet is now three inches below the the fuel cell outlet, and the pump body is visible under the rear valance. The inlet had previously been about an inch below the cell. Picked up 3+ tenths the next weekend. Don't know if the same thing will work for Bill or Chad, but it costs nothing to try. __________________ Tony Curcio 1860 STK

05-26-2010, 03:59 PM	#7
brett3533 Member Join Date: Jan 2007 Location: maysville Posts: 116 Likes: 15 Liked 41 Times in 13 Posts	Re: bog q/jet carbs are very finicky its important to have enough fuel pressure to the regulator to keep the fuel going forward on launch and not to much that your regulator can`t control the pressure from the pump. if it can`t the regulator may bounce or pulse allowing fuel to slowly blow by the needle and seat causing richness for launch making you lean down. I am having similar symptons also w/different combo. hope this helps. magnafuel is the best regulator on market for high pressure pumps. wade owens got my attention from his previous post about moving down his fuel pressure. __________________ Brett McFarland A/S

07-31-2010, 06:51 PM	#9
SS 230 Junior Member Join Date: Dec 2008 Posts: 29 Likes: 0 Liked 1 Time in 1 Post	Re: bog bill, did you fix your problem,if so what was it?

05-26-2010, 08:20 PM	#10
Dean Oliver Junior Member Join Date: May 2002 Location: Stuttgart, AR Posts: 53 Likes: 1 Liked 0 Times in 0 Posts	Re: bog Assuming the tune up is at least close (and I can't emphasize that point enough), the main causes of a Q-jet bog typically are related to: - Too much fuel pressure. Do not depend on one of the little small online gauges for this. Double check your gauge with a second gauge. - Air valve tension too loose. Keep in mind that adjustments should be made in small increments, like 1/8 turn at a time. - Weak fuel system. Simple test. See how long it takes your fuel system to fill a one gallon container. Most SBC stockers with a Q-jet should flow a gallon in no more than 30 seconds through the entire fuel system, regulator and all. - Improperly sized needle/seat (too big or too small) and/or improper float adjustment. This is not an all inclusive list, but it is some of the more common things. A problem that I see too often is that a racer will just assume these things are good rather than take the time to actually check. Hope this helps. Give me a call if you want to talk more about it Bill. Dean