stumble off idle and at wot

[Vaughan_D_W]

Ok, so if you read my other thread, you know that I'm stuck with my 144 for a little while longer, so I'd like it to run better. It starts up and idles fine, both in park and in drive. The spark plugs look good, a nice brown color. I cleaned them and gapped them to .35. The points look good. The problem is that it has a nasty stumble off idle. I have to get on the gas a little bit until it almost stalls, then let off for a second until it picks back up, then get on it again to accelerate. It's bad enough that I've stalled in traffic several times. Also, at WOT (even 3/4 of WOT), it hiccups and bogs down and loses power. I can't maintain 45 mph going up a hill without a head start. If I run it with the choke slightly on, it seems to help. With the spark plugs looking nice, though, it doesn't seem like it's a fuel problem, right? I also have an exhaust leak at the center port. I already put on a new gasket, so I guess I have to get the manifold machined flat now. Even when the manifold gasket was new, though, it still had the idle and WOT problems. Now, the Falcon Six book says the first step is to set the float level and rejet the carb. However, if the plugs look good, is this necessary? Also, the book doesn't say how to set the float. I know you set it by bending the arm up and down, but I don't know what it should be set TO. Could I be experiencing a fuel pump problem here? The pump dowel is loose and slides out and hits the mounting bolts, which keep it from falling out entirely. The book also describes how to set the vacuum level. I'm going to do that as soon as I can get my hands on a vacuum gauge. In the meantime, does anybody have any suggestions, looking at the information I've provided? I'm really not trying to sink a lot of money into this engine, especially on parts I can't transfer over to a 200. Thus, the Load-O-Matic has to stay.

 

[Soldmy66]

I would suggest by starting with (1) accelerator pump setting, and (2) fuel filter.

 

[170-3tree]

^^^whathe said, definitely sounds fuel related.

I would also suggest, to improve performance a touch, advancing your distributor. I believe between 12-15 is typical.

 

[Vaughan_D_W]

Thanks, guys. Fuel filter is easy enough. But I'm not sure about the accelerator pump. It's in the carb, right? What does it look like and how do I set it properly? Also, does anyone know how the float should be set?

 

[170-3tree]

I don't have pictures, by there is a little arm on the side of the carb, that reaches to a piece screwed into the side of the carb, that arm has a connection that has a small adjustment on it at that connection. It would also be a good idea to unscrew that unit to see if the pump itself it's torn. If it is, replace it.

 

[tri-power 250]

Vaughan_D_W,
Where are you located? I have a complete 200 I am selling, if you are interested.
Ken

 

[Vaughan_D_W]

Ken, I'm in Stafford, VA. Between Richmond and D.C. I'm gonna be broke for a couple months, though. That's why I'm messing with the 144.

 

[Vaughan_D_W]

Great success! Ok, at least moderate success. My Mustang no longer stalls when I mash the go pedal. It doesn't really go anywhere in a hurry either lol. I replaced the fuel filter. I don't think that was the problem, though. I took the top of the carb off and cleaned it up inside, although it was already pretty clean, so that probabaly wasn't it, either. Finally, I messes with accelerator pump. My carb has two of them, one on each side, connected by linkage. When I started, the lever on one side would move a little bit starting around 1/2 to 3/4 throttle, and the other side barely at all. The second side has a screw right in the middle. I took both apart and the diaphrams are not torn. I put them back together. Then I started messing with the screw. It was too loose. Looks like the screw adjusts how tightly the arms hold the pumps. I found that if I tightened the screw until it was snug on the pump and then kept tightening it, the rpms would go up. Then I would back it off just a bit until the rpm dropped back down. Then I got to messing with the idle mixture. The funny thing is, if the pump screw was over tightened, I could screw the idle screw all the way in and the car would still idle. Well, that ain't right, so I would back of the pump screw and adjust the idle again. Anyway, after some trial and error and several trips down the driveway and back, my car no longer stumbles and stalls off idle. I'm not entirely sure about the science behind it. I just used the force! Oh yeah, I also set the timing to about 15 or 16 degrees. The marks only go up to 12, so that's an estimate. More test driving and tinkering to come. Hopefully I can get it to make a little power.

 

[JackFish]

Way to go.
A vacuum guage will help the fine tuning.

 

[170-3tree]

^^true. This is also a good time to plug a book for a fellow member of our forum/family/community. The falcon six handbook will give you some info on how toget a bit more on the cheap and ruin your future financial plans for the rest of life if you let it.

It's a good read though. Glad you got done kinks figured out, hope it gets better from there!