1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

[rhillman75]

Just as the title states. I have a 1996 Mercruiser 4.3LX Gen+ Thunderbolt 5 V6 with a MercCarb 2 barrel. I am getting ready to lay it up for the winter and before I do so... I want to check the timing, idle mixture, and idle, because even though I rebuilt the carb... I would like to do one more water test before I put it on a pillow and under a blanket. I have toyed with the idea of buying a multimeter with a tach reading function, but I am stopping at the whole $100.00+ range for an additional meter to add to my toolbox for just one need! I have searched all over the Mercarb 2 barrel for a vacuum hook up and I have found nothing. I do not want to rely on my dash mounted tach alone as it can be and they are known to be inaccurate. I do have a vacuum guage but I don't know if it can used. I have seen the internet postings about using a regular multimeter with a thick wire that goes as close to the number 1 spark plug wire as possible and then using a frequency setting then multiplied by ?, but who knows how accurate this is. Any thoughts before I dunk it for the last time. All local marinas want to charge $200.00+ since they are in the winterizing season of all boats and have to charge extra to pull of volume sales instead of service sales. Any thoughts?

 

[svxtech]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Timing lights with a tach function are cheap...50 bucks or so, 2 birds with one stone. or just do it by ear... Also remember base timing for TB-V.

 

[flintcam]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Actron CP7605 from Amazon $24.04 Tack, voltmeter and Dwell. Works good.

 

[mpdive]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Actron CP7605 from Amazon $24.04 Tack, voltmeter and Dwell. Works good.

Just bought one from there last week. Nice unit.

 

[Struc]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

I liked having the extra functionallity of a multimeter and spent a little more than that, and got this instead:

http://www.amazon.com/gp/product/B0006FM03E

Sinometer SM4380B for $37.50

 

[stonyloam]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Just bought one from there last week. Nice unit.

Got mine a couple of months ago. Agree.

 

[mpdive]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Just as the title states. I have a 1996 Mercruiser 4.3LX Gen+ Thunderbolt 5 V6 with a MercCarb 2 barrel. I am getting ready to lay it up for the winter and before I do so... I want to check the timing, idle mixture, and idle, because even though I rebuilt the carb... I would like to do one more water test before I put it on a pillow and under a blanket. I have toyed with the idea of buying a multimeter with a tach reading function, but I am stopping at the whole $100.00+ range for an additional meter to add to my toolbox for just one need! I have searched all over the Mercarb 2 barrel for a vacuum hook up and I have found nothing. I do not want to rely on my dash mounted tach alone as it can be and they are known to be inaccurate. I do have a vacuum guage but I don't know if it can used. I have seen the internet postings about using a regular multimeter with a thick wire that goes as close to the number 1 spark plug wire as possible and then using a frequency setting then multiplied by ?, but who knows how accurate this is. Any thoughts before I dunk it for the last time. All local marinas want to charge $200.00+ since they are in the winterizing season of all boats and have to charge extra to pull of volume sales instead of service sales. Any thoughts?

Don't overthink it too much. Get a tach or go to the auto parts store and they will let you borrow one with a deposit. Warm the engine up. Put engine at base timing. Disconnect the throttle cable and set your base idle. Then set the mixture screws by turning them in till engine begins to falter. Back out slowly till you get the highest rpm and leave them alone. Make sure your cable is preloaded and reinstall. Recheck idle speed and have a beer.

 

[rhillman75]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Just bought one from there last week. Nice unit.

I decided to say the hell with it and I ordered one this morning. Its's cheap and at least I have something for measuring tach readings now rather than trying the "I think it sounds right" game!

 

[mpdive]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Sounds good. Did you get one with an inductive pick up?

 

[rhillman75]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Sounds good. Did you get one with an inductive pick up?

WellI got the one that was previously mentioned...Actron CP7605.

 

[rhillman75]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Okay... so Thursday I am dropping it in the water for the last 4 days of the year and I am pulling it out on Sunday. Here are the steps that I am planning on doing. Please correct or add if you like!

1. Start it in the water and bring to normal temp
2. Turn it off, ground the puple/white to "neg" terminal on the battery for "base mode"
3. Adjust my MercCarb 2 barrel mixture screw to 1-1/4 out from light seat
4. Adjust my idle screw to where it just contacts the cam and then turn clockwise 2 more turns
5. Pull off throttle cable
6. Start the engine with the Actron meter hooked to the coil and adjust ONLY the mixture screw in or out to get the highest RPM
7. Adjust the idle screw to bring it down to 650-700 RPM

Does the commander NEED to be shifted into the forward detent position on the Commander 3000 while in the water and the boat tied to the dock for BEST results? I have heard you can do this on the muffs in your driveway but it can be deceptive when you get it into the water?

I'm not trying to get scientific, but I just want to cover all my bases before I drop it!

 

[mpdive]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

To be honest your not going to notice hardly any idle change when you drop it in gear. Just did a Tahoe Sunday at a loss of 30 rpm. Just bring it in the ballpark and you'll be fine. Remember all these specs are for a new engine. Engines get old and have clearances and need to be tweaked. Make sure it doesn't diesel when you shut it off. Your step by step is good.

 

[rhillman75]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

So with that said... should I just leave it in "neutral" the entire time or shift it to forward detent? Any thoughts on doing this in my driveway?

 

[mpdive]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

If your going to winterize it anyhow then yes do it in your driveway. When you pull it in the spring and get it out on the water you can do the final adjustment then. You are probably mighty close to the factory adjustments now anyhow.

 

[rhillman75]

Re: 1996 Mercruiser MerCarb 2 barrel (final adjustment coming up) need input!!!

Well...the final adjustment was a pain in the *****! I followed my own step by step as earlier post I had made before. With the motor at operating temp, the commander in forward detent, the engine in "base mode", throttle cable unhooked, and I was using the Actron meter for tach I noticed that I could counterclockwise (back out) the mixture adjusting screw almost 2 full turns (was at 1-1/4 out at start) and it gained maybe 100 rpm. So here is what I decided on... I am going to leave the mixture screw out 1-1/2 turns from seat (manual states 1-1/4 for factory setting). It does start to change at 1-1/2 out but it is a LITTLE change, maybe 050 rpm. I also noticed that the idle screw was already at the 2 clockwise turns in from just touching the cam and I was reading just at 700 rpm. I do get a little "clunk" at forward and reverse change over but it does not "diesel" so I am leaving it the hell alone. I figure the worse thing is that with it being 1/4 turn out more than the factory 1-1/4 setting... it might run a little rich at idle... but I notice the motor doesn't "shake" as much like it's thirsty for fuel at the 1-1/4 setting.