Stumble during acceleration

[Anonymous]

Not too long ago, i replaced the carb on my 220 ci with another autolite 1100 fro RBS( i think). It was from napa. After doing this, the engine stumbles when revving it up in neutral, accelerating from a stop, and accelerating any speed. It feels like the stumble happens at the same time, as soon as i press the gas pedal. When i am driving downthe highway, i can feel the engine surging a little, as if there is a dead spot. And it happens even when i feather the pedal. I know this problem has to do with the carb because it didnt start doing this until i replaced the old one with this rebuilt RBS carb.

What do you all think could be causing this??

The acceleraion pump is brand new and has no tears...could the linkage need to be bent more to make it kick in sooner? Im going to check that out tomorrow to make sure the linkage moves the pump as soon as the pedal is depressed.

The timing and vaccum are both good, and all of the ignition stuff is new. Such as the condenser, points, dizz cap,wires, spark plugs.I can tell that the coil is good bc it produces a blue spark.

Thanks for the help

 

[pedal2themetal45]

Maybe you got the vacuum lines crossed up if your running the load-a-matic.:
tim

 

[CZLN6]

Howdy 66stangontheway:

We're down in Sunny SoCal, so I may not be able to follow up with you, but- I'm piecing together that you have a '66 Mustang with a 200 (not a 220) with a stock 1100 Autolite carb.

You also mentioned an RBS. That's confusing. If you did get a Carter RBS, your problem is that your Load-a-Matic distributor is not compatible with the RBS, which does not have a SCV. It was used on '70 and later 250 engines and supplies a ported vacuum source to the distributor.

Please verify which carb you have. An RBS will never run right with a Load-o-Matic type distributor. If indeed you got an RBS replacement, you have two choices; Replace the RBS with a stock '66 200 Autolite 1100 with a SCV, or replace your stock'66, Load-O-Matic distributor with a post-'68 to be compatible with the Carter RBS carb.

Know that the RBS has a higher CFM rating at 215 as compated to 185 for a stock '66 1100. The performance upgrade choice would be to upgrade the distributor to compliment the RBS. Verify what you have.

If you'll post back with more details, others will be able to help you.

Adios, David

 

[Anonymous]

Is your accelerator pump adjusted correctly?

 

[Anonymous]

you should also check the float in the carb. I had a problem like this a while back and it ended up that the float was getting stuck and wasn't letting enough fuel in during acceleration.

 

[Anonymous]

Sorry about the confusion. Its a 1966, with the 200ci and autolite 1100 carb. Im not sure which manufacture rebuilt it, but it came from napa (whoever they get to do their carbs). Its also just has the orginal load-a-matic.

Alright, I took the carb apart today and brought the diagram with me. Everything is in perfect shape, and the bowl is filled to the correct depth.
The only thing I noticed was that the "accelerator pump discharge weight" was missing. What exactly does this do? And should it be there? I havent tried messing with the accelerator pump rod because i just wanted to rule this out first.

Thanks for the help

 

[JackFish]

The only thing I noticed was that the "accelerator pump discharge weight" was missing

Isn't that supposed to hold down a little ball? Yeah, you need it.

 

[Anonymous]

Yeah, its supposed to hold down the little ball bearing, but it came from the remanufacturing company like that. Could they have forgotten to put that weight in?

Isnt the weight made of brass, and a little longer than the brass stopper for the float stopper? Because i think i saw it in my old reuild kit.

 

[Anonymous]

good luck, and keep us posted, I'm curious to see what the problem is.

 

[Anonymous]

I think i have a lead on the stumble problem. The hose leading from the pcv valve to the base of the carb was really cracked up. So i pulled it off to see if it would hold suction, and it wouldnt. It was hissing like crazy. So left the hose off, and plugged the base of the carb. Then i put a breather in place of the pcv, leading the hose from the breather down to the bottom of the firewall. I started it up, and found that it the engine didnt much nearly as much.

The fuel mix screw was turned almost all the way out before, but after using this setup the i was able to turn it in about 1 or 2 more times. Which is better. I think the carb wasnt getting enough vacuum due to the leaking hose.

Now i am just adusting the timing, and it is getting closer to perfect (smooth) acceleration.

The problem left is that the engine surges just a little when driving at steady speed. But so far i am very pleased. No more stalling off the line.

Where could i find a new pcv hose to replace this one. I know that you are not supposed to use heater hose, but im not sure what is the correct type.

Thanks