Rochester Carb Needs Help to Low Idle

[gjcombs]

All,

I had my new rebuilt carb professionally cleaned this winter in an effort to chase another problem. However there still is another issue with the performance of the carb. This issue existed before it was cleaned.

I ran the boat to sufficiently warm to where it should idle down around 700 RPM. However the idle after a run tends to be around 1200 RPM. I adjusted the low idle screw on the PORT side, but the carb lever on that side that should rest against it is not close to it. I have to manually adjust the mechanism (spring and levers thing) toward the back of the carb to ease the idle down.

How do get my carb to idle lower on its own?

Jason

 

[Jeepster04]

Re: Rochester Carb Needs Help to Low Idle

So you adjust the idle to 700rpm and after you run the boat it idles at 1200. Have you checked for a vacuum leak? If it has a diaphram that opens the choke check that thing out. That was bad on both of our rochester carbs which didnt allow us to properly set the idle/air mixture screws. It was screwing with everything.

About the idle screw, are you saying youre adjusting the screw and the lever isnt bottoming out(youve got to push it closed)??

 

[gjcombs]

Re: Rochester Carb Needs Help to Low Idle

Thanks.

I'll check for leaks.

That is what I am saying. I have to use my hand to push the idle down so that it sets on the tip of the screw. Runs pretty well otherwise. It does fall on its face when trying to go to four barrel. I have to really ease into opening it up.

1981 Viking 190 SI
350 GM, Rochester Carb
800 Sterndrive
Hyrdo-mech shift

 

[gjcombs]

Re: Rochester Carb Needs Help to Low Idle

Bubba,

Are you saying to use WD-40 to find vacuum leaks?

I will double check for sure!

Jason

 

[Susquehanna Squid]

Re: Rochester Carb Needs Help to Low Idle

Thanks gj for starting this thread, I have the same problem. And, thanks for the heads up Bubba!

 

[gjcombs]

Re: Rochester Carb Needs Help to Low Idle

Pig,

Also read this potentially-related post.

http://forums.iboats.com/showthread.php?p=2146929&posted=1#post2146929

Jason

 

[gjcombs]

Re: Rochester Carb Needs Help to Low Idle

Bubba, et al,

I sprayed WD-40 around the base of the carb and did not notice a change in idle speed.

Would adjusting the two needles for the fuel mix help? The shop manual gives guidance on doing this. However, I want an opinion on if this will do any good. The manual describes using a vacuum meter, but says you can adjust it without one by monitor RPMs.

Thanks in advance.