Quadrajet problems - Page 3

Terry Cain · 09-29-2017, 09:17 AM

Tighten air flap spring just a hair and see if that helps.

Jim Kaekel · 09-29-2017, 09:36 AM

Quote:

Originally Posted by mike pearson

danny did some beautiful work on q jets.

x2!

ChevelleStocker · 10-04-2017, 03:06 PM

How much fuel pressure do you guys suggest for a Quadrajet?
I spent a few race weekends this year struggling with the hesitation issue and couldn't find out what was the problem. So now I'm wondering if too high fuel pressure could cause this issue as we raised it a little during last summer.

Hacksaw · 10-04-2017, 03:51 PM

Iv'e had more than one "carb guy" tell me that 5.5 lbs of fuel pressure is max.

Mike Pearson · 10-04-2017, 04:36 PM

Quote:

Originally Posted by Hacksaw

Iv'e had more than one "carb guy" tell me that 5.5 lbs of fuel pressure is max.

I run mine a 6 lbs. low pressure and plenty of volume is what is needed on a Q Jet. one gallon in 30 seconds is about the minimum you can get away with.

ChevelleStocker · 10-05-2017, 01:02 AM

Thanks guys, so it looks like I'll have to lower the fuel pressure when we can get to the track the next time. Now I was running with 7 lbs pressure, so it's interesting to see if that could fix the bog when launching.

Future Super Stocker · 10-11-2017, 10:56 AM

I build quite a few Q-jets. . For the small block I recommend .135 needle and seat. Use a Y-block off the regulator to the carb for a supply of fuel volume and use 5.5 - 7 fuel pressure. 6.5 is more than enough for the Q-jet. Rear flaps may need adjusting, but really done at the track.They should open at 1.350 for most and tension is adjusted 1/8" of a turn tighter or looser. Your Accl. pump shot can also be modified as well. There is mods that can be done to the carb for better performance. WD-40 and Marvels Mystery oil is your best friend. Keep all shafts and linkage lubricated. Hope this helps.

Future Super Stocker · 10-11-2017, 11:52 AM

Danny Ashley I believe started the slide plate for the secondary rods. But note that the air horn needs to be milled in the area that the slide plate goes
.

09-29-2017, 09:17 AM	#21
Terry Cain Senior Member Join Date: Feb 2008 Location: Georgetown, Indiana (close to Louisville, KY) Posts: 775 Likes: 530 Liked 230 Times in 106 Posts	Re: Quadrajet problems Tighten air flap spring just a hair and see if that helps. __________________ Terry Cain ???? STK tcain19689585@gmail.com

10-04-2017, 03:06 PM	#23
ChevelleStocker Junior Member Join Date: Jul 2013 Location: Vantaa, Finland. Posts: 23 Likes: 0 Liked 35 Times in 3 Posts	Re: Quadrajet problems How much fuel pressure do you guys suggest for a Quadrajet? I spent a few race weekends this year struggling with the hesitation issue and couldn't find out what was the problem. So now I'm wondering if too high fuel pressure could cause this issue as we raised it a little during last summer. __________________ K/S #570 '74 Chevrolet Malibu Classic

10-04-2017, 03:51 PM	#24
Hacksaw Senior Member Join Date: Sep 2016 Posts: 880 Likes: 202 Liked 306 Times in 172 Posts	Re: Quadrajet problems Iv'e had more than one "carb guy" tell me that 5.5 lbs of fuel pressure is max.

10-05-2017, 01:02 AM	#26
ChevelleStocker Junior Member Join Date: Jul 2013 Location: Vantaa, Finland. Posts: 23 Likes: 0 Liked 35 Times in 3 Posts	Re: Quadrajet problems Thanks guys, so it looks like I'll have to lower the fuel pressure when we can get to the track the next time. Now I was running with 7 lbs pressure, so it's interesting to see if that could fix the bog when launching. __________________ K/S #570 '74 Chevrolet Malibu Classic

10-11-2017, 10:56 AM	#27
Future Super Stocker Junior Member Join Date: Aug 2013 Posts: 53 Likes: 1 Liked 3 Times in 3 Posts	Re: Quadrajet problems I build quite a few Q-jets. . For the small block I recommend .135 needle and seat. Use a Y-block off the regulator to the carb for a supply of fuel volume and use 5.5 - 7 fuel pressure. 6.5 is more than enough for the Q-jet. Rear flaps may need adjusting, but really done at the track.They should open at 1.350 for most and tension is adjusted 1/8" of a turn tighter or looser. Your Accl. pump shot can also be modified as well. There is mods that can be done to the carb for better performance. WD-40 and Marvels Mystery oil is your best friend. Keep all shafts and linkage lubricated. Hope this helps. Last edited by Future Super Stocker; 10-11-2017 at 11:13 AM.

10-11-2017, 11:52 AM	#28
Future Super Stocker Junior Member Join Date: Aug 2013 Posts: 53 Likes: 1 Liked 3 Times in 3 Posts	Re: Quadrajet problems Danny Ashley I believe started the slide plate for the secondary rods. But note that the air horn needs to be milled in the area that the slide plate goes .