Adjusting my Holley 4160

[Twainer]

This old 1977 351W does not have vacuum ports to do this the way most do it. I say old but it is a freshly reman engine & the carb has been re-built as well. I have started with the idle mixture screws 1 1/2 turns out each. I have read one article that states turn one screw in until it starts running bad, then turn it out until it reaches the highest rpm then turn back 1/4 turn. Do both sides like this.
I have also heard instead of turning out until highest rpm turn out until it starts running bad again & then split the difference.
My attemps have been turn in until it runs bad, turn out until it runs smoother & higher rpm. On mine I keep turning out & nothing changes.
Any help would be greatly appreciated. I haven't messed with a 4bbl since the late 80's

 

[jimmbo]

I use a vacuum gauge and adjust for highest vacuum in gear. If the engine doesn't respond to the mixture screws, then something else is out of spec. Retarded timing, fuel level incorrect, vacuum leak.

 

[kenny nunez]

If the rebuilder used the wrong metering block to throttle body that will cause what you are describing. Also if the idle stop screw is turned too much the intermediate circuit is drawing fuel and the idle mixture screws cannot control idle. Make sure the base gasket is correct, some can cause a vacuum leak. When everything is right usually only 1 ot 1.5 turns on the idle stop screw is enough.
If your engine still has points change it to a Petronics. Set the timing @ the lowest rpm to make sure the centfical advance is not starting.

 

[Twainer]

Jimbo cant use a vacuum gauge as there is no vacuum ports on this old model. Kenny, I rebuilt the carb so it is the one that came with it. Unless the previous owner install the wrong one. I did here from the boat shop that helps me out once in awhile say there is something getting blocked in the metering block. I take it apart, spray carb cleaner down it followed by compressed air. I get much better response out of the mixture screws & feel I get it set up pretty close only for it to do the same thing all over again after 6-8hrs. use. When I had the boat all apart I pulled the gas take out & cleaned it very well but it is acting like it's getting a little dirt or something in the metering block after so many hours of use. :grumpy:

 

[jimmbo]

Can you post a picture of it?
No ports on the throttle body?
Does it have an integral choke pulloff, or an external vacuum break pull off?

 

[Scott Danforth]

No need for vac port.

Wrong or damaged power valve or throttle plates not adjusted properly will cause the issues mentioned.

Who did the rebuild? You or a shop?

Each passage of the metering valve needs to be probed by passing a fine wire thru them.

Also, there are two styles of metering plate to carb body gasket. If you use the wrong one, a direct bypass of the power valve is created

With carb off and throttle closed, blades should be in middle of bypass slots

If correct gaskets are used, and throttle plates closed, with idle mix screws, you should be able to kill the motor by turning them in

 

[Twainer]

Scott, I did the rebuild. It had been rebuilt by a shop but had sat for 10 years & had some fuel in it. I did the best I could cleaning it out with carb cleaner & air compressor. I did not have a tank to soak it in the proper way. Also seems like after 6-8 hours of driving it & tweaking the mixture screws something gets into a passage of the metering block. Gets to where one or both of the mixture screws stop responding to adjustments. I pull it off the carb clean it again. Put it back on & both are adjustable again. There is a rubber o-ring that seats with the screw then there is a rubber/cork gasket on the outside which I assume is to keep the screw from getting out of adjustment from vibration. Could fine pieces of cork be getting into the metering block?

 

[Redrig]

You can get a vacuum gauge on it, its just a little different process for marine

On your intake manifold on one of the runners there will be a steel plug , like half inch in size . Pull that and get a brass barb that adapts to that and your vacuum gauge and your good to go . Full manifold vacuum right there

That's how I dialed in my Holley .

 

[Scott Danforth]

Scott, I did the rebuild. It had been rebuilt by a shop but had sat for 10 years & had some fuel in it. I did the best I could cleaning it out with carb cleaner & air compressor. I did not have a tank to soak it in the proper way. Also seems like after 6-8 hours of driving it & tweaking the mixture screws something gets into a passage of the metering block. Gets to where one or both of the mixture screws stop responding to adjustments. I pull it off the carb clean it again. Put it back on & both are adjustable again. There is a rubber o-ring that seats with the screw then there is a rubber/cork gasket on the outside which I assume is to keep the screw from getting out of adjustment from vibration. Could fine pieces of cork be getting into the metering block?

most likely if the boat sat for 10 years, the crud in the fuel tank is flaking off and ending up in your carb. do you have a fuel/water separator filter?

no need for a soak tank, a simple coffee can works for a holley as most of the parts you need to soak a bit unbolt from the body.