Gas Engine Idle?

[No Yacht Yet]

HELP!!! I have been banging my head off the wall since tuning the beasts up before splash down in late April. Replaced caps,wires, rotors,igntion pickups, plugs, fuel filters, (carb fiters).Timed the two pigs per Merc Cruiser Specs. Carbs look great,air fuel mix on the money. No slap from timing chains. They both sound sweet. After they warm up they idle at 650 rpm. That is untill they get a slight blip of throttle,or just gain a little rpm, one or the other will swing to full advance and gain about 100 to 125 rpm. This makes docking become very interesting in adverse condtions! What the @#$%# am I missing or is this normal??? Brian 1986 Bertram 33 FBC Mercruisers Seahorse Ellisville Harbor, Ma

[lobsta1]

Brian, How about if you disconnect the throttle cables from the carbs? Warm the engines up & then try blippin(technical term) the throttles. If the problem is gone, you now know it is either cables or adjustments on the throttles. Al

[Keith]

Do you have an engine Syc switch maybe its on

[No Yacht Yet]

I had the throttle cables off and it still does the same thing. Sync switch was off also. I'm not sure how that switch is wired though. Al,have you had a timing light on your engines? Mine both go to full advance when the rpm goes from 650 to 750. Is that normal? Brian 1986 Bertram 33 FBC Mercruisers Seahorse Ellisville Harbor, Ma

[lobsta1]

Brian, Full advance should not come in until about 3000 rpm where it will most likely be 32 degrees total advance. That will be 8 degrees initial & 24 advance. I've been told 3000 is where you should actually set your timing. Here is a good resource for a lot of info. There are a lot of pages to navigate. Al http://www.marinemechanic.com/site/index.html

[Miss B]

Could also be the fact that the springs on your distributor centrifical advance are missing, so the weights fly out and then timing goes plus xxx degrees, even at small adjustments of throttle. You could also have slop in your distributor drive gears, which will allow the distributor shafts to move more than they should and affect the timing. The other issue might be a carb issue, you could have excess play in the throttle body plate bushing, which allows air to leak in through the bushing, or the slop in it allows for uneven throttle openings. Before you screw around with the carb though, put a vacuum gauge on the engine,at a non-ported spot on your intake manifold and see what it shows you. Vacuum guages are one of the easiest to use, and most informative tools you can have, and a good one is less than $20. It will come with a chart showing you what the readings mean.

[No Yacht Yet]

Miss B I don't have advance weights under my distibutors. I will take a look at the vacuum for a pressure drop. Brian 1986 Bertram 33 FBC Mercruisers Seahorse Ellisville Harbor, Ma

[lobsta1]

Brian, Forgot to ask you how you resolved this problem? Al

[No Yacht Yet]

It has not happened for quite some time. I think it might have crappy fuel form the winter layover Brian 1986 Bertram 33 FBC Mercruisers Seahorse Ellisville Harbor, Ma