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Old 06-12-2013, 10:29 PM
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Q jet need help in setup

I bought a Q jet awhile back #17080260 off 1980 cutlass 307/350
not sure on the engine.
I ordered an hr kit from Cliffs and 3 sets of air bleeds and idle tubes, idle mixtures, Primary rods, secondary rods and jets. nothing was left untouch.
even replaced the bolts.
I rebuilt her and put her on a 326 Pontiac slightly modified from stock.
Cam is a Comp Cam Cl 51-221-4 kit cam has good idle.
I can get her to idle, but the mixtures screws don't affect the idle, I had them at 5 turns out, but left them at 4 turns out, now my eyes burn from the exhaust.
The APT screw is set to 3 turns, part throttle is smooth.
The vac. adv. is on full manifold vac. and set to 6* BTC and it seems to be sputtering or misses out the exhaust.
What am I doing wrong?

The Primary rods are #39 and jets are #68
Secondary rods are DA with a K hanger

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Old 06-13-2013, 12:49 AM
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For starters I think it needs more timing. You have no adjustment from the idle mixture screws which could be due to several reasons.
First is float is set too high causing it to flood.
next is trash in the needle and seat causing it to flood.
Next is fuel pressure too high causing it to flood.
Next is low spark timing requires the idle to be opened up so much the butterflies are off the idle circuits so it's pulling fuel from the main boosters.
Get a flashlite and shine a light in the carbs throat while at idle, if you see fuel coming out of the boosters then it has one of the problems I mentioned.
I'm not sure if you mean it has 6 degrees advance with vacuum advance but if it does that's far too low, which is causing the problem you mention.
Besides that, once you get the issue settled, to idle correctly the mixture screws shouldn't need anymore than 3 turns maximum out. It's best to set them by RPM to where it's the highest or by vacuum gauge to the highest vacuum.
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Old 06-13-2013, 07:14 AM
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Quote:
Originally Posted by raguza123 View Post
I bought a Q jet awhile back #17080260 off 1980 cutlass 307/350
not sure on the engine.
I ordered an hr kit from Cliffs and 3 sets of air bleeds and idle tubes, idle mixtures, Primary rods, secondary rods and jets. nothing was left untouch.
even replaced the bolts.
I rebuilt her and put her on a 326 Pontiac slightly modified from stock.
Cam is a Comp Cam Cl 51-221-4 kit cam has good idle.
I can get her to idle, but the mixtures screws don't affect the idle, I had them at 5 turns out, but left them at 4 turns out, now my eyes burn from the exhaust.
The APT screw is set to 3 turns, part throttle is smooth.
The vac. adv. is on full manifold vac. and set to 6* BTC and it seems to be sputtering or misses out the exhaust.
What am I doing wrong?

The Primary rods are #39 and jets are #68
Secondary rods are DA with a K hanger
The primary throttle blades are open too far. To fix this you likely need more initial advance.

Info on setting up a performance timing curve is here.

Check to see if the main nozzles are dripping fuel at idle. If they are you will want to add some idle bypass air by enlarging the orifices. Some small displacement carbs came w/o any bypass air but they can be drilled to add it.
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Old 06-13-2013, 08:12 AM
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The timing is 6 deg BTC without adv. when I connect the adv. it seems to up the idle a little.
I left the Idle bypass air alone, it was plugged and the base not drilled out.
Float is set to 5/16" and she is clean inside and out.
The fuel pump is a stock mechanical and the engine runs with my other carb an AFB
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Old 06-13-2013, 09:19 AM
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Bump your timing up to 12* and hook your vac advance to a true manifold vac port. Not to a ported port that shows a little vacuum because the throttle is open too far at idle.
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Old 06-13-2013, 09:43 AM
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Leaky bottom plugs let raw fuel drip directly into the intake manifold,


A lot of people do everything right when rebuilding Q junks , but don't know about the little plugs under the carb. That with age and especially after cleaning or dunking in Gumout will leak!!! They look like little fishing lead shot and are overlooked!! I and other builders even forget sometimes and take them for granted. They can leak fuel while the engine is off , or look sealed till you start the engine and the vacuum will pull fuel by the plugs!

This is probably not your problem but could cause what your experiencing During a rebuild I seal them with a slow curing epoxy

Jester
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Old 06-13-2013, 10:45 AM
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Quote:
Originally Posted by painted jester View Post
Leaky bottom plugs let raw fuel drip directly into the intake manifold,


A lot of people do everything right when rebuilding Q junks , but don't know about the little plugs under the carb. That with age and especially after cleaning or dunking in Gumout will leak!!! They look like little fishing lead shot and are overlooked!! I and other builders even forget sometimes and take them for granted. They can leak fuel while the engine is off , or look sealed till you start the engine and the vacuum will pull fuel by the plugs!

This is probably not your problem but could cause what your experiencing During a rebuild I seal them with a slow curing epoxy

Jester
I guarantee that is not his problem. The Qjet well plug problem really applies to the 1967-earlier carbs that used pressed-in sheet metal well plugs. Doug Roe elevated this to the world consciousness in his book. Since 1968 GM has used spun-in thick aluminum well plugs. I've never seen one leak in four decades of using Qjets. I'm sure you've never seen a leak after putting epoxy on them, but then again, you've probably never seen a car with deer whistles hit a deer, either. Can't prove a negative.

Back to the OP. The biggest question here is: Is this Qjet from a CCC car or not? 1980 could have gone either way. In any case, the 307 carbs are not the best place to start. The air valves are limited to only 70 deg of opening. These carbs were originally calibrated to use EGR, so the mid-range is usually leaner than you would want for non-EGR. I understand that you've changed a lot, but still I'd start with an older carb.
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Old 06-13-2013, 11:28 AM
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Originally Posted by joe_padavano View Post
I guarantee that is not his problem. The Qjet well plug problem really applies to the 1967-earlier carbs that used pressed-in sheet metal well plugs. Doug Roe elevated this to the world consciousness in his book. Since 1968 GM has used spun-in thick aluminum well plugs. I've never seen one leak in four decades of using Qjets. I'm sure you've never seen a leak after putting epoxy on them, but then again, you've probably never seen a car with deer whistles hit a deer, either. Can't prove a negative.

Joe:
I did say it probably wasn't his problem!!!! And seeing how you can guarantee it
no one needs to bother with it any more on carbs manufactured after 68.

Glade you take them for granted Early castings had leaky plugs because of bad design the secondary wells were sealed with a brass cup-plug through '68, and all of them leaked at one point or another. Later a new aluminum plug and a new swagging process was introduced in 1969, and it was better but some still leak with age. And I have seen them leak on late model carbs!!! Its not as prevalent but still happens. You can check them by putting soap and air pressure on the passage but I just seal the plugs and take no chances.

[QUOTE= Tech Topics >> Fuel System
Diagnostic Dilemmas: Servicing Quadrajet Carburetors
Failure Points:
Leakage from the secondary metering well plugs are the most common Quadrajet failure.
Because the Quadrajet was a mass-produced carburetor, it suffered from a few failure points in its basic design. The most notable failure in a Quadrajet is the secondary metering rod well plugs leaking fuel into the intake manifold air stream. The symptoms of leaking well plugs are a rich idle air/fuel mixture or a rolling idle caused by a fuel drip into the intake air stream.

Early Quadrajets used brass well plugs that could be replaced with a more durable O-ringed aluminum plug. The well plugs on later Quadrajets were swaged into the main body and are better sealed with a hardening epoxy like JB Weld or a similar [QUOTE]



LOL I put on deer whistles and hit 4 deer in one month LOL I took em off and never hit a deer since!!!! It was like the whistle beckoned them to come out and play in the road

When you take anything for granted remember: Murphys law "Anything that can go wrong, will go wrong". like Q jet well plugs LOL

Jester

Last edited by painted jester; 06-13-2013 at 11:58 AM.
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Old 06-13-2013, 01:11 PM
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Originally Posted by painted jester View Post
Joe:
I did say it probably wasn't his problem!!!! And seeing how you can guarantee it
no one needs to bother with it any more on carbs manufactured after 68.
OK, fair enough.

I'm a little sensitive because EVERY SINGLE Qjet thread must have at least one post about leaking well plugs. The reality is that 99.99% of the time, they are not the issue, but it does cause a lot of distractions from finding the real issue. The OP's bigger problem is that he's got a new, emissions-calibrated Qjet with all kinds of screwy settings like the limited air valve travel and the mid-range lean calibration for EGR.
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Old 06-13-2013, 02:10 PM
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Quote:
Originally Posted by joe_padavano View Post
OK, fair enough.

I'm a little sensitive because EVERY SINGLE Qjet thread must have at least one post about leaking well plugs. The reality is that 99.99% of the time, they are not the issue, but it does cause a lot of distractions from finding the real issue. The OP's bigger problem is that he's got a new, emissions-calibrated Qjet with all kinds of screwy settings like the limited air valve travel and the mid-range lean calibration for EGR.
Joe: I agree with all of that LOL He made a poor choice! I don't dislike Q jets their better then the Edelbrocks LOL I rebuild them a lot (but not since I retired) and have for over 40 years and put them on many classic and Restored cars! I just rebuilt a (period correct) Qjet and installed it on a 1965 Riviera Gran Sport!

I understand the sensitive statement, I have a few things I am sensitive about that novices pick up and repeat on the web that they believe is fact (every thing on the internet is true "RIGHT" ) The statement I made about the plugs wasn't a blanket statement meaning all Qjets had the problem A builder over the years may build a few hundred carbs and never see a problem but then there's the one in the 10 thousand you don't want to see

Jester
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Old 06-13-2013, 02:42 PM
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I did seal them with JB Weld, both prim. and sec. wells.
I talked to Cliff Ruggles and he felt it was good enough for a 326, the engine is no big performer anyway.
I read where it was used for 2 engines 307 and 350 and I know it's a emissions carb. it's not a CCC carb. it has a power piston and 2 rods but it has a APT to limit the travel of the power piston.
I've been told the secondaries are not sealing cause I hit the air valve open by accident and she stalled.
I was gonna use a 73 455 carb, but the rods and jets are too big and bleeds also.
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Old 06-13-2013, 05:44 PM
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I have found canadian cars in salvage yards...in florida no less, that had OE non CCC carbs on them. They looked just like the 49 states model, but since were made for canadas less strict emission laws, they had not the electronic solenoid etc.
Case in point: A buddys 83 Le Sabre had the 307 olds motor.
We put a straight HEI on it and with great luck stumbled across a non CCC carb on the same car manufactured in canada.
Car ran good and he could work on it without my help.
Just wanted to share that as it may help some in the future
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Old 06-13-2013, 09:45 PM
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Since I can't run this Carb you say, I do own another Q jet a # 7042262 off a 455 Pontiac.
What would have to do to get it run?
Change out the Jets and rods?
What would be the good starting point?
Would I need to change the air bleeds?
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Old 06-14-2013, 05:40 AM
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Originally Posted by LATECH View Post
I have found canadian cars in salvage yards...in florida no less, that had OE non CCC carbs on them. They looked just like the 49 states model, but since were made for canadas less strict emission laws, they had not the electronic solenoid etc.
Case in point: A buddys 83 Le Sabre had the 307 olds motor.
We put a straight HEI on it and with great luck stumbled across a non CCC carb on the same car manufactured in canada.
Car ran good and he could work on it without my help.
Just wanted to share that as it may help some in the future
Canadian cars didn'get the CCC system until 1985 or 86:
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Old 06-14-2013, 08:54 AM
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I do know this, I am coming off the rear port that is at 45deg out the throttle body, this port is full manifold vac. I have the timing set at 6 deg BTC with no Adv. applied, I noticed when I tie the adv. back in, the idle doesn't jump up like it does when I have a Carter AFB on the engine.
It seems to make me think I still have a vac. leak somewhere.
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