Carburetor Issues - School me
 

I have a 226 H-series in my 41 (not stock to car). It has the Holley 847 carburetor on it. Supposedly it was rebuilt, but I can not attest to the quality of the rebuild. It worked when I first put it on a few years ago. But it never idled right. I couldn't get it to idle below 700 RPM. It usually stuck around 900 RPM.
I have been having this problem with my linkage where it will stick when the engine starts to get to a certain temperature. I know how to fix it now. I was driving it around last weekend and it got stuck at full throttle, and the nut loosened and fell out. So I couldn't get it pulled back. I limped it to the side of the road and shut it off. I had to get it towed home.
I fixed the linkage but now the idle is even higher than normal. It's closer to 1100 RPM and I can't get it to go lower. I looked down the carburetor while it was running and fuel is coming out of the main nozzle and not thru the idle circut. My throttle plate looks like it is partially open just a hair.
So the first picture is how the idle is supposed to work. The second is when the choke is on. This is how it appears to be working, except my choke isn't hooked up. So the choke plate is full open. I backed the screw out that rides on the choke cam to open the main plate slightly. Still nothing. It's dumping gas out of that main nozzle. If I press down on the main arm to close the throttle plate, it will start to idle better. But I have to put a lot of pressure to get it closed enough. I'm stuck right now. Carburetors where never my thing.

Re: Carburetor Issues - School me
 

The throttle plate in the carb must open and close completely without binding, and the linkage and return spring must also function without binding. If you can see any failure of the throttle "butterfly" to match the throat of the carb with the linkage removed, inspect the plate to see if it is bent or otherwise damaged. Check the accelerator pedal to see that it is free to move. Inspect the idle needles in the carb to be sure that they have not been overtightened. The ends should not show rings on the pointed part. Finally, check to see that all hoses that connect to the intake are pliable and not cracked from age. Any small vacuum leak will affect the idle speed.

Re: Carburetor Issues - School me
 

Is the throttle butterfly supposed to be fully closed with no air being able to get by at idle? Currently it has a slight gap, maybe 1/16" of an inch or less.

Re: Carburetor Issues - School me
 

Your problem, is most likely that the throttle butterfly's won't close down. 1/16" is to much. it could be compounded by a vacuum leak, too but, start with the throttle.

I'd remove the carb (easier to work on that way), back out the idle adjusting screw and disassemble all linkage to the throttle. Check to see when the throttle plate closes all the way, one thing at a time.

If none of the above correct it, something will be wrong with the throttle shaft or plate.

To much gasoline won't cause it to idle fast, it will actually cause it to slow or stall.

A vacuum leak, increases idle speed, because the idle mixture is rich but, to large a vacuum leak, will kill the engine. Engines will only run within a certain A/F mixture.

Re: Carburetor Issues - School me
 

Check to see if the throttle shaft lever is not peened well onto the throttle shaft. If this gets sloppy (worse with time) the throttle shaft can open the plates slightly when the lever is in the closed position.


Sal

Re: Carburetor Issues - School me
 

Hi Joe
I replaced the carburetor on my H engine with a 7HA carb off ebay.
Then a rebuild kit. Now it runs great.
I think the rebuild kit cost more than the carburetor did.


Bruce

Re: Carburetor Issues - School me
 

I just got a rebuild kit. So I am going to see if I can figure this out myself.

Re: Carburetor Issues - School me
 

First, try flipping each of the throttle plates over. One at a time. Sometimes that helps.

Al Hook

Re: Carburetor Issues - School me
 

Just as an update:
I took the carb off and cleaned it out. The throttle closed perfectly. It seemed that there was some gunk preventing it from closing fully.
Got it back on the car and found out my linkage was also holding it open slightly. After some modifying, I got it to work. I drove it around for a bit the other day and it is so much better. I got the idle down to 500 RPM instead of the 900 RPM it was at before.

Re: Carburetor Issues - School me
 

Good job 41Joe. Thanks for posting the results.


Sal