Carb tuning

[Pmt133]

Good afternoon all. So after the fiasco with the water leak and the "pop" through the intake, which was documented here and finally fixed, ended up just being lean. I finally got around to swapping in the 4 barrel intake and carb. Spent the last couple weeks just running it and now I am at the point to need to tune it. The intake is the Edelbrock marine vortec V6 intake and the carb a good mercruiser/weber AFB pulled from a V6 mercruiser pre-dating my engine. I went through and tanked and cleaned the carb and threw a new rebuild kit at it prior to doing anything.

There is a thread on here where the carb jetting was roughly settled on and so, since I had those parts laying around from other projects, I started there. And I went out and was hard lean. Surging, not running great etc. So for my vacation 2 weeks ago I just threw jets at it and roughly ended up where a stock edelbrock 1409 would come for the weekend. And it ran fine but you could smell it was a little rich and upon pulling the plugs, yeah... rich, but not overly.

So now I have to get it dialed in. I've messed with carbs in cars before so I get what needs to be done. Now after being in this and in a Holley, for something this mild this thing is so much easier to tune in my opinion. Just seems more intuitive but there is a lot less you can mess with too. That being said, am I wrong in following the edelbrock guide for jetting and meter rod changes and then just checking the plugs for fine tuning? The edelbrock is more or less a carbon copy it seems... My plan right now is as follows:

• Throw a rod at it to go a little richer just to see if it gets worse... it probably will.
• Pull one jet size out of it and see if it gets better. Check plugs
• If better do that again until it stops feeling any better and look at the plugs. Fatten up a jet size then mess with rods at part throttle.
• play with rods until it stops feeling better then back off a step again. Check plugs
• Run the **** out of it and make sure plugs look fine.
• Enjoy

Am I in the ballpark here?

 

[Scott06]

there have been a few threads - I think in this one two guys ended up wit the same tune on a vortec 4.3 ... https://forums.iboats.com/threads/stumbling-edelbrock-1409-4-3l-v6.670697/page-2

another one

Edelbrock 1409/2114 on stock 4.3L Vortec engine

I?ve seen a lot of posts here from people asking if anyone has changed from a 2-barrel carburetor to a 4-barrel carburetor on a stock 4.3L Vortec engine. My boat is a 1997 Sea Ray 185BR with the Mercruiser 4.3LX Gen+ engine. According to the Mercruiser Service Manual #18, 4.3LX refers to the...

forums.iboats.com

what ever you do yes read the plugs but you have to do it such that you run at 'X" rpm for a few minutes, then stop it and pull the plug , otherwise you are just reading the idle mix....

on my 1409 I had some slack in the accelerator pump linkage that was causing a lean spot off idle and on holeshot. bending the rod to make sure the pump spring had taken up any slack cured it

 

[Pmt133]

there have been a few threads - I think in this one two guys ended up wit the same tune on a vortec 4.3 ... https://forums.iboats.com/threads/stumbling-edelbrock-1409-4-3l-v6.670697/page-2

another one

Edelbrock 1409/2114 on stock 4.3L Vortec engine

I?ve seen a lot of posts here from people asking if anyone has changed from a 2-barrel carburetor to a 4-barrel carburetor on a stock 4.3L Vortec engine. My boat is a 1997 Sea Ray 185BR with the Mercruiser 4.3LX Gen+ engine. According to the Mercruiser Service Manual #18, 4.3LX refers to the...

forums.iboats.com

what ever you do yes read the plugs but you have to do it such that you run at 'X" rpm for a few minutes, then stop it and pull the plug , otherwise you are just reading the idle mix....

on my 1409 I had some slack in the accelerator pump linkage that was causing a lean spot off idle and on holeshot. bending the rod to make sure the pump spring had taken up any slack cured it

Pumps good. I don't have a lean spot just feels like you'd expect a rich engine to behave. Little slow compared to how snappy it was when it was scary lean lol.

I started at ricks jetting (first link) and had all the odd surging and what not so I jetted up. Odd that second link is a bit leaner. I was reading by staying at speed for half hour then going key off at speed.... a little scary but did it. I wonder if because its a rebuild the cam is different enough I have to change jetting.

This was about 3 hours at 3200 before rejetting.


Same speed and time after jets:


I have an ottoscope I also use to look at the base of the porcelain as well. The second set has a nice Grey band where there was nothing on the first one.

 

[nola mike]

there have been a few threads - I think in this one two guys ended up wit the same tune on a vortec 4.3 ... https://forums.iboats.com/threads/stumbling-edelbrock-1409-4-3l-v6.670697/page-2

another one

Edelbrock 1409/2114 on stock 4.3L Vortec engine

I?ve seen a lot of posts here from people asking if anyone has changed from a 2-barrel carburetor to a 4-barrel carburetor on a stock 4.3L Vortec engine. My boat is a 1997 Sea Ray 185BR with the Mercruiser 4.3LX Gen+ engine. According to the Mercruiser Service Manual #18, 4.3LX refers to the...

forums.iboats.com

FWIW, that first tune is what I first went with and it was CRAZY lean. Also, IIRC the factory weber has 3 step metering rods vs the 2 with the 1409.

on my 1409 I had some slack in the accelerator pump linkage that was causing a lean spot off idle and on holeshot. bending the rod to make sure the pump spring had taken up any slack cured it

Interesting. Mine has been doing that for a while, only bothers me when trying to pull a skier. Have been planning on taking it apart, but maybe I'll look into this first.

Michigan motorz uses a stock 1409 as their carb for their vortec 4.3s. Personally, I think trying to plug chop a boat is voodoo unless you're way off. I know scott06 did it on his 5.0, but I think I'm the only one I've seen that installed an a/f meter to tune the carb on a 4.3. I got it almost right before other things took over. I was still a bit rich on the secondaries but otherwise was running around 14:1. Unfortunately, it doesn't appear that I ever documented what I ended up at. I'll definitely take note if/when I open the carb again.

 

[Scott06]

FWIW, that first tune is what I first went with and it was CRAZY lean. Also, IIRC the factory weber has 3 step metering rods vs the 2 with the 1409.



Interesting. Mine has been doing that for a while, only bothers me when trying to pull a skier. Have been planning on taking it apart, but maybe I'll look into this first.

Michigan motorz uses a stock 1409 as their carb for their vortec 4.3s. Personally, I think trying to plug chop a boat is voodoo unless you're way off. I know scott06 did it on his 5.0, but I think I'm the only one I've seen that installed an a/f meter to tune the carb on a 4.3. I got it almost right before other things took over. I was still a bit rich on the secondaries but otherwise was running around 14:1. Unfortunately, it doesn't appear that I ever documented what I ended up at. I'll definitely take note if/when I open the carb again.

yes some of the factory webber carbs used 3 step metering rods not sure which engines etc but there were a few. Can only think it shows that the binary rich/lean didnt work that well.

I found the pump rod linkage slop when I put the AFR meter on. I never would have found it unless I had the meter. It lead to a long lean spot post holeshot when towing for water sports. I was trying to jet around it so it would go way lean for a long period, then swing way rich. I think in the end I ended up basically where I started with it except for a bigger pump nozzle. Just straightening the rod to lengthen it was all it took.

 

[nola mike]

yes some of the factory webber carbs used 3 step metering rods not sure which engines etc but there were a few. Can only think it shows that the binary rich/lean didnt work that well.

I found the pump rod linkage slop when I put the AFR meter on. I never would have found it unless I had the meter. It lead to a long lean spot post holeshot when towing for water sports. I was trying to jet around it so it would go way lean for a long period, then swing way rich. I think in the end I ended up basically where I started with it except for a bigger pump nozzle. Just straightening the rod to lengthen it was all it took.

I've tried changing the holes on the linkage with zero effect, so that's interesting. Of course I don't remember if this has always been present or just since the big dunk.

 

[Pmt133]

Yes the three step rods were there but short lived. seems like .092/.089 and a 686457 metering rod vs the normal 6857. The reman engines seem to be back to the two step rods and that is what was in my carb. I've done the AFR route on the corvette and usually the plug reads agree with the meter so I at least know my eye is right.

I'd love to do an AFR meter but just seems cumbersome tossing those plates in and I don't think I have the room to go any higher on the elbow.