75 New Yorker Hesiatation Update

[Wildbunch02]

I spent the day adjusting my timing and carburetor with my new toy, a $12.99 vacuum gauge from Harbor Freight.
I found a great step by step how to online on a website called milepost garage.
I followed the steps to the T and I found the carb was extremely out of adjustment. I also did a spray test with carb spray and I found all of the carb mounting screws were loose. I guess there is actually a worse mechanic than me out there. After making sure everything was secure, I resprayed intake and carb with carb spray and after I was satisfied that I had no more vacuum leaks I was able to set everything with the vac gauge and I have a max stable reading of 21.75 on my vac. gauge. The timing is set at exactly 8b, anything else she pings.
The test drive gave me a noticeable difference in power, but she still has a slight hesitation.
I went back an checked everything over and over and I can't get rid of the hesitation on take off, or when I accelerate while rolling.
I was unable to stall the engine when I backed out the idle screw, I'm wondering if there is something worn inside the carb which is related to the inability to lower the idle, and my hesitaion. Remember, this carb was rebuilt about 3 years ago according to a tag affixed to it.
I also went back and moved the adjustment on the rod for the accelerator pump, but that made it worse,so I moved it back. I then went to the air door for the secondaries, I gave it a quarter turn more, but again it got worse and I heard it spit which I didn't before. Tomorrow I will try putting that back to where it was.
Any Ideas before I put An Eddie 1406 on?
Thanks again,you guys have been great, I feel like I made progress, but I'm leery that my tq may be ready to become a paperweight because of my not being able to adjust idle down. The screw is backed out all the way and she is idling at 750.
All ideas are appreciated, regards, Eric

 

[Davea Lux]

I spent the day adjusting my timing and carburetor with my new toy, a $12.99 vacuum gauge from Harbor Freight.
I found a great step by step how to online on a website called milepost garage.
I followed the steps to the T and I found the carb was extremely out of adjustment. I also did a spray test with carb spray and I found all of the carb mounting screws were loose. I guess there is actually a worse mechanic than me out there. After making sure everything was secure, I resprayed intake and carb with carb spray and after I was satisfied that I had no more vacuum leaks I was able to set everything with the vac gauge and I have a max stable reading of 21.75 on my vac. gauge. The timing is set at exactly 8b, anything else she pings.
The test drive gave me a noticeable difference in power, but she still has a slight hesitation.
I went back an checked everything over and over and I can't get rid of the hesitation on take off, or when I accelerate while rolling.
I was unable to stall the engine when I backed out the idle screw, I'm wondering if there is something worn inside the carb which is related to the inability to lower the idle, and my hesitaion. Remember, this carb was rebuilt about 3 years ago according to a tag affixed to it.
I also went back and moved the adjustment on the rod for the accelerator pump, but that made it worse,so I moved it back. I then went to the air door for the secondaries, I gave it a quarter turn more, but again it got worse and I heard it spit which I didn't before. Tomorrow I will try putting that back to where it was.
Any Ideas before I put An Eddie 1406 on?
Thanks again,you guys have been great, I feel like I made progress, but I'm leery that my tq may be ready to become a paperweight because of my not being able to adjust idle down. The screw is backed out all the way and she is idling at 750.
All ideas are appreciated, regards, Eric

Try disconnecting the various linkages one at a time to see if any are keeping the throttle plate from properly closing. Also check the screw on the fast idle cam if it has one to be sure that it is not out of adjustment and holding the throttle plate open. If the choke pull off is stuck, it can also cause a higher than normal idle. There are two idle mixture screws at the base of the throttle plate, (they may be covered by plastic caps) if these are set improperly, that can also cause a fast idle. Check the throttle cable to be sure it is not set too short, that will hold the throttle plate open as well. Note that a 750 RPM idle is not that far off the recommended 650-700 range. There is a detailed section on thermo quad repair and adjustments in the fuel section at www.imperialclub.com

Dave

 

[Wildbunch02]

Try disconnecting the various linkages one at a time to see if any are keeping the throttle plate from properly closing. Also check the screw on the fast idle cam to be sure that it is not out of adjustment and holding the throttle plate open. If the idle cam is stuck, it can also cause a higher than normal idle. There are two idle mixture screws at the base of the throttle plate, if these are set improperly, that can also cause a fast idle. Check the throttle cable to be sure it is not set too short, that will hold the throttle plate open as well. Note that a 750 RPM idle is not that far off the recommended 650-700 range.

Dave

Thanks for the reply. I moved the accl cable forward a little, and that did nothing, The linkages did not seem to be holding the throttle open, and where the fast idle screw rests seemed loose, like the fast idle screw was barely resting on it.
As for the mixture screws, I was adjusting them according to the vacuum gauge.
Thanks, Eric

 

[Davea Lux]

Thanks for the reply. I moved the accl cable forward a little, and that did nothing, The linkages did not seem to be holding the throttle open, and where the fast idle screw rests seemed loose, like the fast idle screw was barely resting on it.
As for the mixture screws, I was adjusting them according to the vacuum gauge.
Thanks, Eric

Using the vacuum gauge is a good technique for performance tuning. These were smog motors designed to EPA mandated emissions, so a lot of fuel/air setting were less than ideal. I suspect that if you close the idle screws 1/4 turn, you idle will probably drop down to the 600-650 range. If that does not work, you can always reverse the settings back to where you had it.

Dave

 

[Wildbunch02]

Using the vacuum gauge is a good technique for performance tuning. These were smog motors designed to EPA mandated emissions, so a lot of fuel/air setting were less than ideal. I suspect that if you close the idle screws 1/4 turn, you idle will probably drop down to the 600-650 range. If that does not work, you can always reverse the settings back to where you had it.

Dave

I will try it, but that I don't think that will solve my hesitation problem

 

[Davea Lux]

I will try it, but that I don't think that will solve my hesitation problem

The idle speed will not matter much in that regard. Have you checked the vacuum advance to determine if it is working? Also check your plug gap as a gap too wide will cause hesitation. Another possibility is that your brake booster may have an internal vacuum leak that is causing the engine to lean out.

Dave

 

[Davea Lux]

I will try it, but that I don't think that will solve my hesitation problem

Does the car hesitate any time you push down on the throttle or just from a standing stop? Also do you have a clean air filter installed?

 

[Wildbunch02]

Air filter is new, and it will hesitate at any time

 

[Wildbunch02]

Vacuum advance moves when I suck on hose and it will hold steady until I release it. Plugs are new and gapped at .035, cap and rotor are new. I'm not sure of how to check brake booster for a vacuum leak, but brakes are fine, nice firm pedal.

 

[Davea Lux]

Vacuum advance moves when I suck on hose and it will hold steady until I release it. Plugs are new and gapped at .035, cap and rotor are new. I'm not sure of how to check brake booster for a vacuum leak, but brakes are fine, nice firm pedal.

Thy disconnecting the line to the EGR valve and plug the line off with a screw or something similar and see if this helps with the hesitation. EGR valves carbon up and sometimes get stuck open resulting in poor performance. There is a gasket on the base of the EGR valve that sometimes blows out internally which causes the same result.

Dave

 

[Wildbunch02]

Thy disconnecting the line to the EGR valve and plug the line off with a screw or something similar and see if this helps with the hesitation. EGR valves carbon up and sometimes get stuck open resulting in poor performance. There is a gasket on the base of the EGR valve that sometimes blows out internally which causes the same result.

Dave

Ok, cool, I will give that a check tomorrow, I also sprayed the base of this with carb spray and I don't think there is a vacuum leak there.
Thanks

 

[Davea Lux]

Vacuum advance moves when I suck on hose and it will hold steady until I release it. Plugs are new and gapped at .035, cap and rotor are new. I'm not sure of how to check brake booster for a vacuum leak, but brakes are fine, nice firm pedal.

Most likely the booster is not bad then. One way to check it is to disconnect the vacuum line from the manifold and block off the port on the manifold. If you notice a large change in engine RPM with the booster disconnected, it is most likely leaking. Obviously, do not drive the car in this condition.

Dave

 

[Wildbunch02]

Most likely the booster is not bad then. One way to check it is to disconnect the vacuum line from the manifold and block off the port on the manifold. If you notice a large change in engine RPM with the booster disconnected, it is most likely leaking. Obviously, do not drive the car in this condition.

Dave

Ok, I had that blocked off today, no difference.

 

[Davea Lux]

Ok, cool, I will give that a check tomorrow, I also sprayed the base of this with carb spray and I don't think there is a vacuum leak there.
Thanks

FYI the EGR valve is a closed circuit valve, when operating, it directs exhaust gases into the intake manifold as inert material to keep combustion temperatures down. They usually leak internally due to a blown gasket or carbon fouling of the valve seat. Rarely do they leak externally, so you would not notice a leak by spraying it with carb spray.

Dave

 

[Wildbunch02]

FYI the EGR valve is a closed circuit valve, when operating, it directs exhaust gases into the intake manifold as inert material to keep combustion temperatures down. They usually leak internally due to a blown gasket or carbon fouling of the valve seat. Rarely do they leak externally, so you would not notice a leak by spraying it with carb spray.

Dave

Ok, I didn't know that

 

[Knebel]

If going one direction makes it worse, have you tried going the opposite?

 

[63Fun]

No matter what I would plug off that EGR valve.

If you hesitate no matter what the situation, could sound like a worn accelerator pump. This is assuming you have your ignition and timing squared away.

 

[Wildbunch02]

No matter what I would plug off that EGR valve.

If you hesitate no matter what the situation, could sound like a worn accelerator pump. This is assuming you have your ignition and timing squared away.

Im heading out to the garage now to readjust door for secondaries and plug egr. This carb was rebuilt 3yrs ago, and i dont think it was driven much. I also have strong streams of fuel that i can see when i operate throttle with engine off.

 

[Wildbunch02]

I plugged off Egr valve and that did not help.
I then decided to swap to an Eddie 1406, I removed the Tq and I noticed that the linkage on the 1406 would have required some mods, so I decided to put the Tq back on because I didnt have the time to make the 1406 work.
When I started it up I noticed the idle was considerably lower, around 450, so I decided to re tune it with the vacuum gauge.
I ended up bumping my timing back to 14b,and I had about 21.5vac with carb re-tune.
I took it for a spin and she ran a lot better, the hesitation is still there but it seems much less and is not consistent.
I guess my next step is to order a rebuild kit and swap out the accelerator pump.

 

[Knebel]

Can you tell us, when you cruise down the road and slowly open the throttle just a bit, does it hesitate,then go? And it also does that when you you quickly snap the throttle? Does it do it in park when you snap the throttle while not moving? If so, i would say for sure accelerator pump does not provide enough fuel. Are you able to take a video of this?