Help any input will be welcome

R. Thorne · 02-28-2013, 09:48 PM

4gc carb? Check for leaking brass floats and float setting. Ron.

james schaechter · 02-28-2013, 11:07 PM

Some ignitions like a msd digital programmable have provisions to adjust timing on the launch. Just taking a swing, but if for some reason your timing was retarding a ton on the launch, maybe that would be an issue. It would not show up anywhere else.

Ed, are you running the 283 now? 4 jets have big float bowls. I would be shocked if you ran low on fuel, but what if they were set too high and dumping fuel down the intake when you launched?

gmonde · 02-28-2013, 11:53 PM

do you have a o2 reading ????,, whats the first gear ratio?? gmonde

Mike Taylor 3601 · 03-01-2013, 09:38 AM

It would help to open secondarys on the line 8600 is just where it starts to sound good,LOL
I think you have some good ideals posted, I know it's a 4GC but I have had similiar quadrajet problem,needle and seat will slightly leak won't run over just idles about 100-200 rpm slower and bogs on launch,took me a little bit to find the first time,on Q-jet I have to take off top of carb and hold float pivot pin down and turn on fuel pump it will take 1-2 minutes for fuel to creep up it leaks so slightly,maybe able to try on 4GC. new needle and seat seals,but now I check them before putting top on.
Mike Taylor 3601

njk53 · 03-01-2013, 09:54 AM

What is the fuel pressure doing when this happens?

Jeff Lee · 03-02-2013, 07:17 PM

I think anytime we have to run a carb such as a 4GC and Autolites, and whatever else, when having problems like this it's probably going to save a few grey hairs to bolt a tried & true Holley double pumper of the same CFM rating on it just to see what happens. If it picks up considerably, then you know where to look. If not, then you know your required carb is good and you ned to look somewhere else.

Maverick · 03-02-2013, 08:08 PM

One item that I have done to get the low end torque up when you let out the clutch. I don't run a spacer under the carb any more. Worked on a issue of pulling the motor down after the clutch release, and at the time, I had a one inch spacer, put a two inch spacer on it, and it was worse. Tried a half inch spacer and it got better, then finally ran no spacer. I changed the jetting a little when the spacer changes took place. One thing I noticed was, I had to jet it down when I had no spacer. Racers wll testify, that it will make more power with the spacer, but it is a drive ability issue. A friend of mine that racers super stock with a clutch was having a problem with bogging when leaving the line. Had a two inch spacer. I told him what I did. He didn't believe me. But he tried it. And now he doesn't run a spacer. If you had a convertor it would be a different issue.

02-28-2013, 09:48 PM	#1
R. Thorne Member Join Date: May 2009 Posts: 182 Likes: 62 Liked 100 Times in 33 Posts	Re: Help any input will be welcome 4gc carb? Check for leaking brass floats and float setting. Ron.

02-28-2013, 11:07 PM	#2
james schaechter VIP Member Join Date: Dec 2004 Location: Cumming GA Posts: 1,988 Likes: 1,289 Liked 1,428 Times in 296 Posts	Re: Help any input will be welcome Some ignitions like a msd digital programmable have provisions to adjust timing on the launch. Just taking a swing, but if for some reason your timing was retarding a ton on the launch, maybe that would be an issue. It would not show up anywhere else. Ed, are you running the 283 now? 4 jets have big float bowls. I would be shocked if you ran low on fuel, but what if they were set too high and dumping fuel down the intake when you launched? __________________ James Schaechter 3163 STK

02-28-2013, 11:53 PM	#3
gmonde Senior Member Join Date: Nov 2007 Posts: 615 Likes: 56 Liked 165 Times in 59 Posts	Re: Help any input will be welcome do you have a o2 reading ????,, whats the first gear ratio?? gmonde

03-01-2013, 09:38 AM	#4
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,371 Likes: 352 Liked 306 Times in 103 Posts	Re: Help any input will be welcome It would help to open secondarys on the line 8600 is just where it starts to sound good,LOL I think you have some good ideals posted, I know it's a 4GC but I have had similiar quadrajet problem,needle and seat will slightly leak won't run over just idles about 100-200 rpm slower and bogs on launch,took me a little bit to find the first time,on Q-jet I have to take off top of carb and hold float pivot pin down and turn on fuel pump it will take 1-2 minutes for fuel to creep up it leaks so slightly,maybe able to try on 4GC. new needle and seat seals,but now I check them before putting top on. Mike Taylor 3601

03-01-2013, 09:54 AM	#5
njk53 Senior Member Join Date: Jul 2007 Location: East China, MI Posts: 504 Likes: 0 Liked 0 Times in 0 Posts	Re: Help any input will be welcome What is the fuel pressure doing when this happens? __________________ Nelson Kowal Stock 345

03-02-2013, 07:17 PM	#6
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Help any input will be welcome I think anytime we have to run a carb such as a 4GC and Autolites, and whatever else, when having problems like this it's probably going to save a few grey hairs to bolt a tried & true Holley double pumper of the same CFM rating on it just to see what happens. If it picks up considerably, then you know where to look. If not, then you know your required carb is good and you ned to look somewhere else. __________________ Jeff Lee 7494 D/S '70 AMX

03-02-2013, 08:08 PM	#7
Maverick Member Join Date: Dec 2010 Posts: 299 Likes: 3 Liked 36 Times in 26 Posts	Re: Help any input will be welcome One item that I have done to get the low end torque up when you let out the clutch. I don't run a spacer under the carb any more. Worked on a issue of pulling the motor down after the clutch release, and at the time, I had a one inch spacer, put a two inch spacer on it, and it was worse. Tried a half inch spacer and it got better, then finally ran no spacer. I changed the jetting a little when the spacer changes took place. One thing I noticed was, I had to jet it down when I had no spacer. Racers wll testify, that it will make more power with the spacer, but it is a drive ability issue. A friend of mine that racers super stock with a clutch was having a problem with bogging when leaving the line. Had a two inch spacer. I told him what I did. He didn't believe me. But he tried it. And now he doesn't run a spacer. If you had a convertor it would be a different issue.