Possible carb problem?

[John Vinzant]

Bought boat couple years ago, motor was out of it, and in pieces. Owner had motor bored .030 over and redecked. Head was resurfaced and a valve job done. I was a former auto/diesel mechanic years ago, so reassembling the engine was not an issue. Have an 1980 OMC 3.0L with an 400 Stringer Outdrive. Engine runs great at higher RPMS, but can not get the idle below 900 rpm. According to the service manual, the rpm needs to be 700 or less for the outdrive to shift easily. Running a stock 2 barrel carb, wondering if I need to change to a different carb, possible CFM increase playing with the carb, not letting it idle? Using a Rodchester 2 barrel

 

[lynnboy021]

Re: Possible carb problem?

Did you check your dwell and your timing??? Also you know that when you adjust your idle, boat needs to be in water and on forward gear...

 

[Bondo]

Re: Possible carb problem?

Bought boat couple years ago, motor was out of it, and in pieces. Owner had motor bored .030 over and redecked. Head was resurfaced and a valve job done. I was a former auto/diesel mechanic years ago, so reassembling the engine was not an issue. Have an 1980 OMC 3.0L with an 400 Stringer Outdrive. Engine runs great at higher RPMS, but can not get the idle below 900 rpm. According to the service manual, the rpm needs to be 700 or less for the outdrive to shift easily. Running a stock 2 barrel carb, wondering if I need to change to a different carb, possible CFM increase playing with the carb, not letting it idle? Using a Rodchester 2 barrel

Ayuh,.... I'd sooner think the low-speed circuit is plugged up, or fulla Crud,...

I doubt it has anything to do with the reman block,...

 

[Howard Sterndrive]

Re: Possible carb problem?

181 cubic inch engine bored .030 makes it a 183.5 cubic inch engine. A non-issue for the carb or anything tuning related.

I'd start by looking for vacuum leaks around the carb base or choke tube, and then fuel and points/timing /fuel.

 

[HPjunkie]

Re: Possible carb problem?

I am having the same problem and thinking the carb is the problem. It might be worth it to clean carb and check it out to eliminate that. I have to wait till the ice melts before I can really test it out though.

 

[wrench 3]

Re: Possible carb problem?

I'm curios whether your problem is that it stalls below 900 or that it won't slow down to below 900.

 

[John Vinzant]

Re: Possible carb problem?

Will not idle below 900 without running rough and shutting down.

 

[wrench 3]

Re: Possible carb problem?

It does sound like the carburetor, but still check for vacuum leaks. This is also assuming that timing, firing order, valve timing and valve adjustments are OK.