Hesitation Just off Idle

I did a little searchie for this one and didn't find anything that quite fits. I have finally got down to tuning my 68' v6 2G rebuilt by me with a new brass float. I got the float set what i thought was good last fall and it seemd to run ok even though the timing was by ear only. I set the timing today at around 5 maybe a little closer to 6 and it idles great and runs great except off idle in first gear( I have a th350 I run like a manual:twisted. If I pull th choke out about 1/4 it idles higher and I don't have the hesitation. I don't like running like this. I have not gotten a vacuum gauge yet nor have I set the idle speed.

Any thoughts? I keep reading about the cute little ball bearing in the bottom of the accelerator pump and keep wracking my brain to remember if I put it back in(I think I did but it was a few years ago).

Todd

BTW with the choke a 1/4 out this thin screams. It almost scares me

 

Pertronix. I went out after I posted and re-adjusted the timing way up to (just guessing here) about +20. Idles incredibly smooth but I still have the hesitation to the point it stalled when I took it for a test run. Pulled out the choke about 1/3 and it goes away.

 

Did you set it at 5 degrees static ? Or is that with the vac advance hooked up ? More info on your setup would help us give you more ideas.

 

Looking down into the venturi's do you get two good squirts of fuel when you push the throttle back (without the engine running)? If not then you need to look inside your carb again.

 

Vac advance hooked up, set timing originally to about 5 deg +. Idles decent
Idle mixture screws out about 2.5 each
pertronix in lieu of points.
Checked for vac leaks with WD40 at carb and found none.
This set-up runs ok with choke out 1/4

Vac advance hooked up, set timing to about 20 deg+, idles incredible smooth
Idle mixture reset at 2.5 out
Choke out about 1/3 runs really good.

My set-up is v6/th350/d18. Stock, mechanical fuel pump, no return line.

What other info would help?

Thanks

Todd

 

Yes I do get two good streams(I had my 10yr old daughter pushing the petal)

 

Hmm.. I think you need to set your static timing first. With the vac advanced unplugged and capped. Time it to 5 degrees(or what the manual calls for) at idle speed(650-750, a little bit lower than manual trans) in park, when the motor is fully warmed up with the choke off. After that, hook the vac advance and you could check for total timing by reving the motor up to aprox 3,000 rpms and the timing should be at about 30 degrees. If you have pre detonation or knocking, you will need to retard the timing a little bit until it stops.

I would check your vac advance diaphram to make sure it is in good shape. pull vac on the line and see if it holds vaccum. You can pull the cap and make sure your mechanical timing stuff is not frozed up and moves well.

 

I will check the timing tomorrow and repost.

 

The fact that it runs better with the choke out may be a clue. Try disconnecting the linkage from the choke plate to the fast idle cam so it will go back to base idle & see if you have the stumble with the choke partly out. There may be something causing your fuel mixture to be too lean, like a plugged jet or float set improperly, that the rich choke setting is compensating for.

 

Does your th350 have a vacuum modulator? Could be ruptured diaphragm or leaking line. Plug all vacuum lines and then check timing.

 

I disconnected the fast idle cam and with the choke pulled out 1/4 to 1/3 it still stumbles no change. When i pull it out all the way it dies.

Just for the heck of it i through the timing light on number 2 and with the timing set by ear and smoothness of idle the timing is right around 5. I am sure I had the dots lined up perfect when I installed the timing set but could i be off one tooth?

The timing doesn't seem to affect this stumble. If the float was set too low would this cause the stumble? After All my problems with my old float when I went to the brass one I wonder if I set it too low?

 

Walt, I will try that. I did check for vac leaks around the carb last night and found none but I did not check that line. Back to the jeep!

 

No diaphragm leak. Timing still at like 20. Still hesitating. Float level?

 

More ideas.. check your PCV valve. Something is causing the hesitation, and you just need to find it. For the float level.. if it was too low, you would have problems at WOT.

 

I do not have a PCV at this point. At wide open it runs pretty well with no hesitation. Accelerator pump? If I did not get the ball bearing back in the bottom of the accelerator pump area could that do it?

 

Patrick, I did and low and behold! The ball was present and accounted for but the rubber cup on the accelerator assembly that came with my NAPA kit was turned inside out on the inner portion at the shaft! I will post some pics of it tomorrow whe I get to work. The rubber was very pliant when I pulled it out of the fuel. Once it all evaporated it is a little more stiff which worries me a bit. The rebuild kit also included a leather cup but I am not sure how to use it with the new assembly. I do not have the old assembly but it seems to me it looked like the new one and that was why I used the new assembly and not the leather one.

My concern is that this cup will do the same thing again. I have left the carb apart until I post some pics and I get a opinions on them.

Thanks for all the help

Todd

 

need to use #1 and you must have a vacuum gauge to adjust the carb.

 

I know I know. I am getting a gauge today. Just wierd.