engine racing plus bogs down

[Larry Jones]

Went out for a ride early this afternoon and the engine was idling smoothly. Took it out tonight drove about 4 miles as coming home the engine started to race plus when I wanted to use the passing gear it started to hesitate on me. Like the carb wasn't getting enough gas.This has never happened bebore.I will check the spark plug wires tomorrow. What else would I need to check. AS I said first time for this problem. It will drive smoothly under 40 miles hour. But it started to race on me coming home up to then everything was fine. Thanks Larry

[jopizz]

Check the secondary diaphragm in the carburetor. The rear throttle plates might be sticking open.

John

[Larry Jones]

checking the carb

By removing the air cleaner would I be able to physically observe those plates sticking. The diaphragm is that part deeper into the carberator which Iwouldnt be able to observe. PLus would some carb cleaner down into the throat solve my problem. Thank you again for addressing this problem. John. Would I be able to shoot some cleaner through the front carburetor idling screws without damaging anything.

[Larry Jones]

got my manual out

hi John.

it looks to me there our 4 screws holdind the cover plate along with a return spring and then the secondary operating diaphragm. If I shot some gumout through the opening would that solve anything or maybe I would have to adjust the fast idle adjustment screw too. I don't want to get over my head with this. Larry

[jopizz]

If the diaphragm is torn shooting gumout isn't going to help it. Open the throttle all the way and then move the secondary lever back and forth and look down the carburetor and see if the rear throttle plates close all the way.

John

[Larry Jones]

throttle plate

going away today But did start the engine earlier this morning idled smoothly. Will get to it later today. Larry Thanks John

[Larry Jones]

moving secondary lever

I did what you said. Moving the secondary lever did closed all the way. But the plates looked alittle gooped up. Would you advise alittle gumout on the top plates I would have to get my small finger to get under the bottom plates. What would you advise mre to do. Larry

[jopizz]

Some Gumout on the plates won't hurt. Spray it on top of the plates and open them up and spray it on the bores. Use as much as you want then let it dry. You need to make sure the rear throttle plates close completely or the engine will race.

John

[Larry Jones]

explain the bores

I didn't quit understand the bores. Can you give me a physical description of the bores. New territory for me John.

[jopizz]

The bores are the round parts of the carburetor that the throttle plates close against. The shop manual calls them barrels. I've always called them bores.

John

[Larry Jones]

the bores

Let me see if I understand what we were through John.I indicated that the car started out ok. After about 15 minutes of driving the engine started to race. So that was caused by the secondaries not opening up all the way is this statement correct. My second statement then I couldn't really use my passing when I oprnrd up the throttle and wanted to go pass 40 mph It then started to cough and hesitate then. So in closing when you punch it the secondaries should open up. Before its just the primary that Iam using. Thanks for all of your help. John. Larry

[jopizz]

I'm thinking that the secondaries are opening up before they should causing the car to race. The secondaries should only open up when you hit a high speed and then should close when you decelerate. That's why I suggested that it could be a bad diaphragm. That would also cause the hesitation you describe. I'm just giving you possibilities. Without seeing your carburetor I'm just guessing. It could be something completely different.

John

[Larry Jones]

changing the diaphram

Is changing out the diaphragm be any problem . It looks like in the illustration inmy manual just four screws and a spring or is there more to that. Would nappa have a replacement for that. What purpose does it serve. Bofore I do anything I will clean the plates and the barrels. Thank you John.

[Larry Jones]

carb rebuilt

I had several issues with the engine racing. So I had the choke rebuilt. A new secondary diaphragm gasket installed. Plus there is a small plastic rod that is on the passenger side of the carburetor that broke off also so the secondaryies weren't closing when they should odf when I backed off the gas. Larry