Idle speed on muffs...

[94OMC]

Hi,

There's a sticker on my engine that says the idle speed in fwd gear should be 650 RPM. About what does that translate to on land using muffs? Should be higher on land, right?

I'm asking because I can't get my 1994 5.0L OMC to idle lower than 950-1000 RPM on muffs. I haven't had a chance to take it to the lake yet, but I want to have the engine running close to spec before I get on the water. I know that a high idle speed is not good for shifting.

I've taken the throttle cable off the carb and moved the lever and idle screw as far as I can, and the idle is still around 1000 RPM.

Thanks in advance

 

[Haut Medoc]

Re: Idle speed on muffs...

Ford or GM 5.0?.......
Either way, too high......
What is the choke doing?......

 

[94OMC]

Re: Idle speed on muffs...

Ford, I believe, but not sure where to check? Edit: It's a Holley 2-bbl, so probably a Ford.

I'll take a look at the choke next time I mess with it. I left the flame arrester on it when I was playing around over the weekend.

The choke plates should be standing straight up when the engine is warmed up, right? Anything else to look for?

thanks

 

[Haut Medoc]

Re: Idle speed on muffs...

Ford, I believe, but not sure where to check? Edit: It's a Holley 2-bbl, so probably a Ford.

I'll take a look at the choke next time I mess with it. I left the flame arrester on it when I was playing around over the weekend.

The choke plates should be standing straight up when the engine is warmed up, right?
Yes......
Anything else to look for?

thanks

Excessive fuel dumping in the carb.....
If you cannot get it to idle down it is a carb issue.....
Btw, if the ditributer is in the front = Ford.....
In the back = GM......

 

[94OMC]

Re: Idle speed on muffs...

The distributor is in the front.

Come to think of it, I think it's been idling high ever since running some Seafoam through it last fall. Any reason why that would cause a high idle?

 

[JustJason]

Re: Idle speed on muffs...

it will idle high out of the water. There is no back pressure on the exhaust to slow the idle down.
The correct way to set idle rpm is with the boat in the water in foward gear.
The good news is, is that you can set your base timing on the muffs.... and that won't change weather the boat is in the water or not.
Then you can dump it in the water, start the boat up, and in neutral set your idle mixture. Then put it in foward, and then set your idle rpm.
Before you go checking the fuel system, check your timing. Timing effects idle more than fuel does.

 

[Don S]

Re: Idle speed on muffs...

In reallity, it will idle higher out of the water, but usually not more then 50 to 100 rpms higher.

 

[Haut Medoc]

Re: Idle speed on muffs...

I would definately check the timing as suggested above....

 

[brunolund]

Re: Idle speed on muffs...

what about a vacuum leak???

 

[94OMC]

Re: Idle speed on muffs...

1st thing - I checked the tach, and it was way off. The back of the tach was set to the correct position, but it was reading too high. So I twisted the setting screw around a bit, set it back on the correct setting, and now it's reading correctly. I can use the idle screw to adjust the speed in spec.

2nd thing - checked timing and it is right on 10 deg.

thanks for the help - hopefully I can take it to the lake this weekend and test the idle speed in the water.

 

[Fireman431]

Re: Idle speed on muffs...

Mine idles at 700 on land and 700 in neutral in the water. 650 in gear in water.