RPM idling in bucket vs. body of water?

[sutor623]

1967 Mercury 650 Doing a link and sync. Motor was running at 6-700 RPMs in neutral. Put it in gear and idle went down to 400-500 and stalled. I adjusted the spark advance, and neutral idle went up to 850-900, and in gear (in bucket) it only went up to 550-600RPMs. It ran great at idle in gear. My question is this. When the boat is in a body of water under an actual load, is it going to slow down my rpms even more? If so there is no way this thing will idle in gear.

 

[Texasmark]

Re: RPM idling in bucket vs. body of water?

My engine is spec'd at 675 +/- 25 on the boat, in the water, in F gear, engine warmed up; worded just like that. Back at the dock that translates to 900 give or take in N.

Sounds like you might open up your low speed adjustments on your carbs and let her have a little more fuel. Manual for the adjustments would help, but basically the tweak is to have it running, screw one in till it starts missing then back out 1/2 or so turn. Correct setting is when the engine will just take a load, on the boat in the water, like doing a hole shot, and not load up.

Mark

 

[sutor623]

Re: RPM idling in bucket vs. body of water?

Yeah that's what I figured. I really need to get a timing light, but I am not going to fool with that until I get a new throttle cable and do a full link and sync. For now I just want to be able to idle without stalling out. I tried to adjust the carb jets while in gear and it didnt really alter the RPMs very much. While out of gear it made a big difference. But, it seems like my reeds are in great shape because I can get the motor to idle in gear, in a bucket in about 60 degree weather at around 450 RPMs. Since I was running the motor in a bucket in gear, I guess what I really wanted to know was if the RPMs will be different while in a bucket in gear at idle vs. actually pushing the boat at idle. Do you have any idea Tex?

 

[CV16]

Re: RPM idling in bucket vs. body of water?

I had less than 100 rpm loss when put in the lake as compared to a bucket. I did have one motor that would idle fine in the bucket, but would die in the lake when I tried to idle it. I did the linc and sync and it works just fine now! I only put that in so you don't give up if it doesn't idle for you in the lake. I was ready to pull the plug and make a reef out of my boat for a while!

 

[aussieflash]

Re: RPM idling in bucket vs. body of water?

Was told to go around 250 RPM above spec on muff and in neutral (no load).Set it to 950 RPM.and idles in gear in river right on 700 RPM.
A bucket and a body of water do not compare unless its a proper test tank.

 

[sutor623]

Re: RPM idling in bucket vs. body of water?

I had less than 100 rpm loss when put in the lake as compared to a bucket.

Yeah thats what I was thinking. I too have had issues running IN the water, but a link and sync always fixes that.

 

[sutor623]

Re: RPM idling in bucket vs. body of water?

Was told to go around 250 RPM above spec on muff and in neutral (no load).Set it to 950 RPM.and idles in gear in river right on 700 RPM.
A bucket and a body of water do not compare unless its a proper test tank.

Agreed, but running the boat on muffs vs. in my bucket gives me an extra 200RPMs, so I think that my bucket is ample.

 

[Texasmark]

Re: RPM idling in bucket vs. body of water?

Was told to go around 250 RPM above spec on muff and in neutral (no load).Set it to 950 RPM.and idles in gear in river right on 700 RPM.
A bucket and a body of water do not compare unless its a proper test tank.

That's exactly the right numbers sir.

Mark

 

[Texasmark]

Re: RPM idling in bucket vs. body of water?

Yeah that's what I figured. I really need to get a timing light, but I am not going to fool with that until I get a new throttle cable and do a full link and sync. For now I just want to be able to idle without stalling out. I tried to adjust the carb jets while in gear and it didnt really alter the RPMs very much. While out of gear it made a big difference. But, it seems like my reeds are in great shape because I can get the motor to idle in gear, in a bucket in about 60 degree weather at around 450 RPMs. Since I was running the motor in a bucket in gear, I guess what I really wanted to know was if the RPMs will be different while in a bucket in gear at idle vs. actually pushing the boat at idle. Do you have any idea Tex?

Your idle numbers are too low. On my engine, the carb low speed adjustment sets the idle rpm once you set the timing to idle timing and have the idle speed adjust set where the book says to set it....there are marks to look at and all. Once you have the timing set and the carbs adjusted correctly per the book, any additional rpm changes are accomplished with the idle set screw and that changes the idle timing....faster the timing, faster the idle.

Mark

 

[sutor623]

Re: RPM idling in bucket vs. body of water?

Your idle numbers are too low. On my engine, the carb low speed adjustment sets the idle rpm once you set the timing to idle timing and have the idle speed adjust set where the book says to set it....there are marks to look at and all. Once you have the timing set and the carbs adjusted correctly per the book, any additional rpm changes are accomplished with the idle set screw and that changes the idle timing....faster the timing, faster the idle.

Mark

Aite cool man. thanks for the info. Ill let you guys know how it goes. Im going out for my first true test run this Friday. (With Tach and GPS) Wierd thing is though, how come in Neutral I am at 8-900 and in gear I am at 4-500? It seems that when I put the motor into gear there is a bigger change in idle than normal.

 

[aussieflash]

Re: RPM idling in bucket vs. body of water?

Maybe dodgy gauge?

 

[Texasmark]

Re: RPM idling in bucket vs. body of water?

Aite cool man. thanks for the info. Ill let you guys know how it goes. Im going out for my first true test run this Friday. (With Tach and GPS) Wierd thing is though, how come in Neutral I am at 8-900 and in gear I am at 4-500? It seems that when I put the motor into gear there is a bigger change in idle than normal.

I'd say you were loading up and at that rate I doubt you could get a hole shot. Go through the setup process: Set the idle timing, set the linkage to the marks on the linkage, open the carb idle mixture 1 1/4-1 1/2 turn. Get it running then do as I suggested setting each carb up.

Mark