Just got every thing locked in, timing,spark,fuel everything. But it will run and then stall after a 6 block distance. The rebuilt carb was never tune could it be flooding the engine?
307 runs when it wants, is it running too rich?
- Thread starter TheBandit203
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You need to tune the carb. The idle may be too high and the idle mix is too rich.
i wrote this for someone else having trouble tuning their Qjet
Things you will need.
1. vacuum gauge
2. Tachometer
3. Idle mixture adjustment tool
4. screwdriver
Block your tires! and set parking brake!!
Section 1.
WITH CAR OFF
1. Disconnect and plug the distributer vacuum advance. plug the vacuum gauge into manifold source
2. Turn your idle mixture screws in all the way, but not too TIGHT as you can damage them. Turn them OUT about 3.5-5 turns max. Make sure you turn both out precisely the same number of turns.
With CAR ON
2. Leave the car in PARK, adjust the idle speed screw on side of carb as LOW as it can go without the motor chugging or stalling.
3. Set your initial timing to the specs for your engine. This is the base timing NOT counting the degrees advance of your accretion curve or the vacuum advance.
Your car should run acceptable at this setting. Now you need to fine tune it.
Section 2.
1. Put the car in drive. Have someone with their foot on the brake as well for safety. Your car should NOT be able to move. DO NOT ALLOW ANYONE to press the accelerator, and do NOT open up the throttle with your fingers while your car is in DRIVE.
2. With the car now in DRIVE adjust your idle speed screw again as low as it can do without the car chugging, OR to the RPM on that is on the sticker of your radiator shroud. the car should run smooth and idle nice. Try putting a glass of water on the top of the car and make it so the water is still and no vibration rings. A V8 should run nice and smooth in drive! (depending on the CAM and exhaust resonance you might not be able to get it perfect) If the car can not stay running at the RPM you are aiming for move to next step... THE END GOAL IS TO SET THE RPM AS LOW AS YOU CAN WITH AS LITTLE GAS AS POSSIBLE WHILE STILL HAVING A SMOOTH RUNNING ENGINE
3. with the Idle mixture adjustment screw tool turn out each screw a LITTLE until the car can stay running. Also keep an eye on the vacuum gauge. You should see the gauge rise to a higher and higher number and then STOP and not gain anymore. Once you find where this point happens back it off just a little. Repeat on the other screw. You SHOULD be keeping track of how many turns you turn out each screw and match them as precisely as possible.
4. Check the RPM again. If it has change from the specs on the sticker then turn it up or down again.
5. If you adjusted the speed UP you should be able to turn your idle mix screws DOWN a little bit. Turn them down till you just start to lose some vacuum and then up just a little. Adjust the other side the same always making sure you are just at the max vacuum and correct RPM.
You curb idle speed and mixture is now perfectly set. On a stock 305-350 I think the idle speed in drive is 500-700RPM
note: If your car is not stock (bigger cam?) you might find that you need to readjust your timing a little bit at this point. It is a process of trial and error till you get the car running perfect with as low an RPM and gas as possible. Whatever this timing is you arrive at THIS becomes your BASE/INITIAL timing for the additional step at the end of this...
Step 3.
1. Put the car in park. The RPM should shoot up to about 300-400 RPM (at least on a stock SBC).
2. Plug the vacuum advance back into the correct source. It should be the one that opens up after idle but closed at idle. You do not want it pulling your RPMS up while in park otherwise you are going to have the same problems with the throttle plate opening up and the engine getting too much gas. When the car is in park and low RPM it you should not feel much vacuum from it. If you do check the manual for your carb and find out which port you should be plugging into. ON a stock SBC the vacuum advance is actually plugged into a vacuum delay valve that is in the mess of tubing attached to the manifold water sensor and the air cleaner and NOT directly into the carb.
3. Turn off the car. It should not diesel anymore and your mixtures are set properly for the most vacuum at park and at load (aka in drive).
Last step
1. With the tires blocked and again with the car in DRIVE (and someone on the brake just in case). turn on the AC system. You should use the Tach again to make the RPMS of the engine the same with the AC OFF and ON. If the engine slows down with the AC ON, then put the car in PARK, open up the throttle a little, and turn out the idle solonoid just a enough so that when you let go of the throttle it comes back to rest on the solenoid slightly higher than it did before. Put the car back in DRIVE with the AC on and see if the idle speed is the same in drive as it was drive with the AC off. Keep repeating the process of putting the car in PARK and upping the throttle and screwing the solenoid OUT till you hit the RPM you want. Remember to NOT open the throttle with the car in DRIVE otherwise you are going to run over your blocked tires, over your foot and into the back of your garage or other cars in the driveway! ALso, if your car is revving too high at idle (even though you JUST fixed that) that your parking brake can't keep the car from moving then your rear emergency brake is not going to help much in stopping you! SOOO fix that next!
Additional step
1. Depending on where you set your timing in the first step you MIGHT need to readjust your timing curve and advance stop on your distributer. Unless you are running a stock distributer you need to look up how to do that. Some distributers have a advance stop and little springs that you can change. Some vacuum advance pots you can adjust with a allen wrench, others you can't. In any case you need to start with your Initial Timing you set in the first step and then figure out what you need for TOTAL timing. This is a WHOLE other thread though....
i wrote this for someone else having trouble tuning their Qjet
Things you will need.
1. vacuum gauge
2. Tachometer
3. Idle mixture adjustment tool
4. screwdriver
Block your tires! and set parking brake!!
Section 1.
WITH CAR OFF
1. Disconnect and plug the distributer vacuum advance. plug the vacuum gauge into manifold source
2. Turn your idle mixture screws in all the way, but not too TIGHT as you can damage them. Turn them OUT about 3.5-5 turns max. Make sure you turn both out precisely the same number of turns.
With CAR ON
2. Leave the car in PARK, adjust the idle speed screw on side of carb as LOW as it can go without the motor chugging or stalling.
3. Set your initial timing to the specs for your engine. This is the base timing NOT counting the degrees advance of your accretion curve or the vacuum advance.
Your car should run acceptable at this setting. Now you need to fine tune it.
Section 2.
1. Put the car in drive. Have someone with their foot on the brake as well for safety. Your car should NOT be able to move. DO NOT ALLOW ANYONE to press the accelerator, and do NOT open up the throttle with your fingers while your car is in DRIVE.
2. With the car now in DRIVE adjust your idle speed screw again as low as it can do without the car chugging, OR to the RPM on that is on the sticker of your radiator shroud. the car should run smooth and idle nice. Try putting a glass of water on the top of the car and make it so the water is still and no vibration rings. A V8 should run nice and smooth in drive! (depending on the CAM and exhaust resonance you might not be able to get it perfect) If the car can not stay running at the RPM you are aiming for move to next step... THE END GOAL IS TO SET THE RPM AS LOW AS YOU CAN WITH AS LITTLE GAS AS POSSIBLE WHILE STILL HAVING A SMOOTH RUNNING ENGINE
3. with the Idle mixture adjustment screw tool turn out each screw a LITTLE until the car can stay running. Also keep an eye on the vacuum gauge. You should see the gauge rise to a higher and higher number and then STOP and not gain anymore. Once you find where this point happens back it off just a little. Repeat on the other screw. You SHOULD be keeping track of how many turns you turn out each screw and match them as precisely as possible.
4. Check the RPM again. If it has change from the specs on the sticker then turn it up or down again.
5. If you adjusted the speed UP you should be able to turn your idle mix screws DOWN a little bit. Turn them down till you just start to lose some vacuum and then up just a little. Adjust the other side the same always making sure you are just at the max vacuum and correct RPM.
You curb idle speed and mixture is now perfectly set. On a stock 305-350 I think the idle speed in drive is 500-700RPM
note: If your car is not stock (bigger cam?) you might find that you need to readjust your timing a little bit at this point. It is a process of trial and error till you get the car running perfect with as low an RPM and gas as possible. Whatever this timing is you arrive at THIS becomes your BASE/INITIAL timing for the additional step at the end of this...
Step 3.
1. Put the car in park. The RPM should shoot up to about 300-400 RPM (at least on a stock SBC).
2. Plug the vacuum advance back into the correct source. It should be the one that opens up after idle but closed at idle. You do not want it pulling your RPMS up while in park otherwise you are going to have the same problems with the throttle plate opening up and the engine getting too much gas. When the car is in park and low RPM it you should not feel much vacuum from it. If you do check the manual for your carb and find out which port you should be plugging into. ON a stock SBC the vacuum advance is actually plugged into a vacuum delay valve that is in the mess of tubing attached to the manifold water sensor and the air cleaner and NOT directly into the carb.
3. Turn off the car. It should not diesel anymore and your mixtures are set properly for the most vacuum at park and at load (aka in drive).
Last step
1. With the tires blocked and again with the car in DRIVE (and someone on the brake just in case). turn on the AC system. You should use the Tach again to make the RPMS of the engine the same with the AC OFF and ON. If the engine slows down with the AC ON, then put the car in PARK, open up the throttle a little, and turn out the idle solonoid just a enough so that when you let go of the throttle it comes back to rest on the solenoid slightly higher than it did before. Put the car back in DRIVE with the AC on and see if the idle speed is the same in drive as it was drive with the AC off. Keep repeating the process of putting the car in PARK and upping the throttle and screwing the solenoid OUT till you hit the RPM you want. Remember to NOT open the throttle with the car in DRIVE otherwise you are going to run over your blocked tires, over your foot and into the back of your garage or other cars in the driveway! ALso, if your car is revving too high at idle (even though you JUST fixed that) that your parking brake can't keep the car from moving then your rear emergency brake is not going to help much in stopping you! SOOO fix that next!
Additional step
1. Depending on where you set your timing in the first step you MIGHT need to readjust your timing curve and advance stop on your distributer. Unless you are running a stock distributer you need to look up how to do that. Some distributers have a advance stop and little springs that you can change. Some vacuum advance pots you can adjust with a allen wrench, others you can't. In any case you need to start with your Initial Timing you set in the first step and then figure out what you need for TOTAL timing. This is a WHOLE other thread though....
Non CCC, Edelbrock intake manifold, headers. Hei distributer (vac advance) and custom side exhaust that's it
Timing is set at factory spec, not familiar with jetting where is that on the carb?olds307 and 403 said:
TheBandit203 said:
I don't have enough info to diagnose but ill throw a dart for ya. Is the engine up to operating temp before the six block journey? Does it start back up right after stalling? In the past, I've had a bad HEI module cause the car to stall after warmed up. Also, how is the fuel pressure. Fuel filter new? Did you rebuild the Qjet yourself? If so, to what specs?
TheBandit203 said:
this should be your first thing to check. It should be done regardless of whatever else could be wrong. Run on or dieseling is caused by a number of things, but because you said the carb has not been tuned I would guess that is exactly the problem.
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