Topic: Quadrajet replacement options?
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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Lifetime MemberC3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18378
Vette(s): Used to own a 1979 Corvette now owned by JB79
Right off the bat, I have an issue. There is a paper that came with the carb that says: "Before removing your old carb, determine if the vacuum port is timed (no vacuum at idole) or full (vacuum present at idle)."
Also in this picture, there is a metal line going from the back of the carb to the intake. The 1406 does not have a spot for this line to connect. Will I no longer need it?
In this picture, there is a rubber line with a little black/yellow plastic piece on it...it connects to the front of the q-jet and to the thermostat housing. Will I no longer need this with the 1406? What will I do with the open port on the valve it connects to on the thermostat housing?
Lastly, there is a metal line that goes from the rich/lean dial to the same place on the intake as the other metal line mentioned above. Again, no place for the for the 1406. Is that because the 1406 has an electric choke? What will I be doing with the port on the intake if neither of those metal lines will be going there anymore?
Thanks!
Adam Wartell 2010-03-20 08:39:01
Do any of you have an answer for that, or do I actually have to get it running and warmed up to pull the line off to check it? Is it the line in the front of the q-jet that is all the way to the drivers side?
Also in this picture, there is a metal line going from the back of the carb to the intake. The 1406 does not have a spot for this line to connect. Will I no longer need it?
In this picture, there is a rubber line with a little black/yellow plastic piece on it...it connects to the front of the q-jet and to the thermostat housing. Will I no longer need this with the 1406? What will I do with the open port on the valve it connects to on the thermostat housing?
Lastly, there is a metal line that goes from the rich/lean dial to the same place on the intake as the other metal line mentioned above. Again, no place for the for the 1406. Is that because the 1406 has an electric choke? What will I be doing with the port on the intake if neither of those metal lines will be going there anymore?
Thanks!
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
C4 Vette Registry, C6 Vette Registry
My first Vette, now owned by JB79:
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
You're gonna want to use the timed port.
To try and answer some of your questions I'll use my experience with the '78 L82 I had. With a 2101 intake you won't be reusing the EGR, so that and the other smog equipment attached to it can be dispensed with. Get a standard type small block thermostat housing and do away with the original and its vacuum switch and connections. My car ran much better and somewhat cooler as well. A cleaned up appearing engine bay is a bonus.
Lifetime MemberC3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18378
Vette(s): Used to own a 1979 Corvette now owned by JB79
[QUOTE=Gunslinger]You're gonna want to use the timed port.
[/QUOTE]
To try and answer some of your questions I'll use my experience with the '78 L82 I had. With a 2101 intake you won't be reusing the EGR, so that and the other smog equipment attached to it can be dispensed with. Get a standard type small block thermostat housing and do away with the original and its vacuum switch and connections. My car ran much better and somewhat cooler as well. A cleaned up appearing engine bay is a bonus.
Ok. Cool. So I traced the line coming out of the front driver's side of the q-jet (center of picture below) and it runs to a bunch of emission control stuff. If that is all coming out, how do I know which is the vaccum line needed to plug into the new carb?
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
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My first Vette, now owned by JB79:
Former Member
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Frederick, MD - USA
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Vette(s): 1969 convertible L71 427/435 4-speed black interior
I'm not sure, but I think you'll want to connect your distributor advance vacuum line to the timed port. The other port can be capped off. Other vacuum lines can be connected to the manifold connections for them.
Lifetime MemberC3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18378
Vette(s): Used to own a 1979 Corvette now owned by JB79
The thick hose in the center of this picture (front of the q-jet) goes to what I think is the vapor canister in the driver's fender. Again, there is no port that matches this on the Edelbrock. What do I do with it?
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
C4 Vette Registry, C6 Vette Registry
My first Vette, now owned by JB79:
Lifetime MemberC3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18378
Vette(s): Used to own a 1979 Corvette now owned by JB79
Another hose with no future home.
This hose runs from that silver canister on the distributor to the front passenger side of the q-jet. Is this the vaccum line that is needed for the "timed vaccum port" on the new carb?
Also, if you look close at the middle of this picture, you'll see this line is completely burnt. It was laying against the intake manifold. No wonder the car was running like crap!
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
C4 Vette Registry, C6 Vette Registry
My first Vette, now owned by JB79:
Former Member
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Frederick, MD - USA
Joined: 9/8/2003
Posts: 3398
Vette(s): 1969 convertible L71 427/435 4-speed black interior
The "silver canister" on the front of the distributor is the vacuum advance...that hose goes to the timed port on the front of the Edelbrock. Yep...that burned through hose was creating a huge vacuum leak!
That big hose I'm not sure about. You may have to call and ask an Edelbrock tech on that. Maybe it can connected to the manifold vacuum port...there are many size "T"'s made for vacuum lines. Maybe someone else here can be of more help...I'm on my way out the door for the day.
Best of luck...nothing's insurmountable. You'll have it squared away...nothing worthwhile comes easy!
Lifetime MemberC3VR Founder
Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18378
Vette(s): Used to own a 1979 Corvette now owned by JB79
Well, this is interesting.... the folks over at CF seem to be highly recommending that I do NOT do this switch.
Can you guys take a look at what they're saying and let me know what you think?
Thanks!
-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry
C4 Vette Registry, C6 Vette Registry
My first Vette, now owned by JB79:
Interesting read on both. I switched to a new carb when I swapped the engine, so I'm biased. I just didn't put that intake on the engine since it already had one.
I bet if you replace that vacuum line it'd run a helluvalot better.
I'll take some pics under my hood tomorrow and post them up since ours are similar. I've been out working on the 04 all day. I'm leaving Monday so I'm going to try to enjoy tomorrow.
I bet if you replace that vacuum line it'd run a helluvalot better.
I'll take some pics under my hood tomorrow and post them up since ours are similar. I've been out working on the 04 all day. I'm leaving Monday so I'm going to try to enjoy tomorrow.
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Adam,
Obviously LARS is a bit biased about the Q-Jet, but he sure knows his stuff!
I'll say it again and again that a nicely rebuilt Q-Jet is the way to go.
IMHO you should replace the burned up vacuum advance line first and see how the Q-Jet reacts.
I'd hate to see you open up a can of worms and still have issues after spending your time and money.
Kevin
in Forum: C3 Fuel, Emission Control, and Exhaust Systems
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