'77 quadrajet or rebuild the old one??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

68gmsee · 09-04-2007, 11:59 AM

Need to get some opinions...

I've got an older qjet carb (mechanical choke) on my 69 with 350 and it's needing some work. I have another nice one that came off a 1977 350 that's in good condition and has electric choke.

My question is if I use the 77 will there be any problems capping off the lines I don't need? And which one goes to the distributor?

pic of the 77 qjet...

ChevLoRay · 09-04-2007, 12:09 PM

If you know it's good and worth putting a kit in, go for it. I don't happen to like any of the early emissions carbs. So, I bought a new Q-Jet from Edelbrock. Never happier with a Q-Jet, than I am with this one.

68gmsee · 09-04-2007, 02:22 PM

Chevloray, the 1977 qjet seems to be in real good shape and probably doesn't need any work done to it for now. At least, I hope...

I intend to eventually go back to the original configuration, but for now I just needed to know if there would be any problems with blocking off all of those extra openings for the emissions crap on the 77's.

neonlarry · 09-04-2007, 03:42 PM

Blocking off unused ports will not affect the performance of the carb. As to which port to use for vacuum advance it depends on if you want to use ported or nonported vacuum.

68gmsee · 09-04-2007, 05:56 PM

Quote:

Originally Posted by neonlarry

Blocking off unused ports will not affect the performance of the carb. As to which port to use for vacuum advance it depends on if you want to use ported or nonported vacuum.

Thanks for the info, larry, but when it comes to the later quadrajets I'm a total moron. Not sure what you mean by "ported or non ported vacuum" and how will it affect the performance. This is basically a work truck used for hauling and pulling.

68gmsee · 09-04-2007, 06:46 PM

Okay, I did a search on ported vs non ported and found out what I was needing.

The port above the butterfly is the ported vacuum and the ones at the base are the manifold vacuum. I will check them with my vacuum guage. From what I read it doesn't matter which one I use. I just have to determine which one my engine likes better.

I need 2 ports for my 350. The pcv one in front and another for the vacuum advance. I'll cap off the rest off...

ChevLoRay · 09-04-2007, 07:55 PM

How long has this '77 carb been sitting around? Was is rebuilt and then set up, or pulled from a running vehicle and stored? I would replace the accelerator pump (dried out) and pull the throttle plate from the carb and be sure the plugs in the base of the bowls are not leaking. This is the source of most of the ills that Q-Jet's are notorious for having. You can buy the plugs from NAPA and the foam pieces that fit into the base plate to help hold the plugs in tightly.

68gmsee · 09-04-2007, 08:12 PM

ChevLoRay, not sure on how long it's been sitting. I am sending the older one out to have it cleaned and redone so I'm just going to install the 1977 one to see if it works until I get the other one back.

If it doesn't work good, then I'll just park the truck until I get my other one back.

Thanks for the help..

neonlarry · 09-04-2007, 08:31 PM

The later Qjets usually don't have a problem with leaky well plugs, they changed the plugs to solid ones instead of stamped ones.

DieselEater · 09-04-2007, 08:46 PM

Buy Cliff Ruggles book on Q-Jets!!!!!!!!

09-04-2007, 11:59 AM	#1
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	'77 quadrajet or rebuild the old one??? Need to get some opinions... I've got an older qjet carb (mechanical choke) on my 69 with 350 and it's needing some work. I have another nice one that came off a 1977 350 that's in good condition and has electric choke. My question is if I use the 77 will there be any problems capping off the lines I don't need? And which one goes to the distributor? pic of the 77 qjet...

09-04-2007, 12:09 PM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: '77 quadrajet or rebuild the old one??? If you know it's good and worth putting a kit in, go for it. I don't happen to like any of the early emissions carbs. So, I bought a new Q-Jet from Edelbrock. Never happier with a Q-Jet, than I am with this one. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

09-04-2007, 02:22 PM	#3
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: '77 quadrajet or rebuild the old one??? Chevloray, the 1977 qjet seems to be in real good shape and probably doesn't need any work done to it for now. At least, I hope... I intend to eventually go back to the original configuration, but for now I just needed to know if there would be any problems with blocking off all of those extra openings for the emissions crap on the 77's.

09-04-2007, 03:42 PM	#4
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Re: '77 quadrajet or rebuild the old one??? Blocking off unused ports will not affect the performance of the carb. As to which port to use for vacuum advance it depends on if you want to use ported or nonported vacuum. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

09-04-2007, 06:46 PM	#6
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: '77 quadrajet or rebuild the old one??? Okay, I did a search on ported vs non ported and found out what I was needing. The port above the butterfly is the ported vacuum and the ones at the base are the manifold vacuum. I will check them with my vacuum guage. From what I read it doesn't matter which one I use. I just have to determine which one my engine likes better. I need 2 ports for my 350. The pcv one in front and another for the vacuum advance. I'll cap off the rest off...

09-04-2007, 07:55 PM	#7
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	Re: '77 quadrajet or rebuild the old one??? How long has this '77 carb been sitting around? Was is rebuilt and then set up, or pulled from a running vehicle and stored? I would replace the accelerator pump (dried out) and pull the throttle plate from the carb and be sure the plugs in the base of the bowls are not leaking. This is the source of most of the ills that Q-Jet's are notorious for having. You can buy the plugs from NAPA and the foam pieces that fit into the base plate to help hold the plugs in tightly. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

09-04-2007, 08:12 PM	#8
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: '77 quadrajet or rebuild the old one??? ChevLoRay, not sure on how long it's been sitting. I am sending the older one out to have it cleaned and redone so I'm just going to install the 1977 one to see if it works until I get the other one back. If it doesn't work good, then I'll just park the truck until I get my other one back. Thanks for the help..

09-04-2007, 08:31 PM	#9
neonlarry Registered User Join Date: Feb 2002 Location: Vacaville, CA Posts: 2,746	Re: '77 quadrajet or rebuild the old one??? The later Qjets usually don't have a problem with leaky well plugs, they changed the plugs to solid ones instead of stamped ones. __________________ 70 C/10 Light Red 350/TH350, HEI, Duals w/40 series Flows, 91 seat, LED taillights 99 Pontiac S/C GTP, SLP Ram Air hood, GMPP Konis & springs 95 Neon ACR, MP PCM, AFX UDP, 3.0 CAI

09-04-2007, 08:46 PM	#10
DieselEater Registered User Join Date: Dec 2006 Location: Trinidad, Colorado Posts: 642	Re: '77 quadrajet or rebuild the old one??? Buy Cliff Ruggles book on Q-Jets!!!!!!!! __________________ 69' 3/4 4X4 470ci BBC 700 HP.... D60/14bolt 205/465 http://profile.myspace.com/index.cfm...ndid=127691959



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