4.3L & 1409 Carb Tuning

[Volphin]

I'm not happy with my carb tuning and will be dialing it in this weekend. I am running the Vortec heads on a non balance shaft 4.3L with the Edelbrock 1409 carb, performer manifold and 1.6 RRs. She just seems lean on takeoff. The carb is equipped with the 1409 4.3L calibration kit, .089 primary .089 secondary a 68/57 metering rod and pink 7" spring. This ran fine before I upgraded my heads. I have picked up some .070 x .047 metering rods and still have the stock .071 x .047 metering rods. I was going to pop in the .070 rods in and retest. Any advice from my fellow boaters?

V

 

[Bondo]

Re: 4.3L & 1409 Carb Tuning

I'm not happy with my carb tuning and will be dialing it in this weekend. I am running the Vortec heads on a non balance shaft 4.3L with the Edelbrock 1409 carb, performer manifold and 1.6 RRs. She just seems lean on takeoff. The carb is equipped with the 1409 4.3L calibration kit, .089 primary .089 secondary a 68/57 metering rod and pink 7" spring. This ran fine before I upgraded my heads. I have picked up some .070 x .047 metering rods and still have the stock .071 x .047 metering rods. I was going to pop in the .070 rods in and retest. Any advice from my fellow boaters?

V

Ayuh,.... Read This, 'n buy a street/ strip tunin' kit...

 

[John_S]

Hopefully, Edelbrock provided a tuning matrix for the baseline 4.3L kit. Otherwise, it will take a bit of time figuring out one, since it is off the standard 1409 chart.

Have you tried changing the accel pump rod location to the richest setting?

The rods you are choosing seem to be making the power much richer, but the cruise a bit leaner???

FWIW, the Merc SM for the 4.3L vortec head weber used .092 primary jet with a three step 68/64/57 rod. So, maybe a .092 jet with your 68/57 rod would be a better starting point. That should get you on the standard 1409 tuning matrix, someplace between ref 9 and ref 10.

PS: Stock 1409 rods should have been 68/47.

 

[mpdive]

Re: 4.3L & 1409 Carb Tuning

Hi Volphin. When you say lean on take off, are you referring to a momentary flat spot or or a lean out at a specified rpm when your in the primary circuit. My first thought was acc. pump needed a richer setting unless you already tried this. Figured another half cc of go go juice might have been the cure.

 

[Volphin]

Re: 4.3L & 1409 Carb Tuning

Seems I have the AP set for rich blast. lol
When I recover from tonight and tomorrow I'll dig into it some more... helping my better half tonight and tomorrow with her student field trips. Targeting Sunday.

V