Lambda to adjust carb

[MCL]

Hi

Just wondering if you can use a lambda sensor to adjust the carb.I have a 4.3 vortec with various performance parts including a edelbrock 1409 carb.They sell these external lambda kits for 200 bucks thats has a sensor to bolt to the manifold and a gauge that displays the af ratio.

I know that these sensors dont last in boat engines because of the presence of moisture and salt.But how about just for dialing in a carb and then plug it.I have alum manifolds and since the coolant doesnt circulate at the "foot" of the manifold that connects to the exhaust port,it would be easy to drill and tap for the sensor,of course it would only tell the af of one cylinder,but it would give and estimate at where the af at.

Fuel over here is 3 times as expensive as what you pay for in the states,so it would also gain to have the af spot on for fuel economy.It would also make carb adjusting so much more easier.

Any insight on why this could/couldnt work?

 

[RogersJetboat454]

Re: Lambda to adjust carb

I know that these sensors dont last in boat engines because of the presence of moisture and salt.

It's not because an A/F ratio sensor doesn't last long in boats, it's because they don't work while being drown with water. The sensor needs dry hot exhaust to work correctly. Something a boat does not offer.

Unless you have an exhaust I don't know about, you should have water circulating through your manifolds and out the exhaust, or your rubbers would be toast.

A vacuum gauge, and reading plugs is the best way to tune your carb IMHO.

 

[Don S]

Re: Lambda to adjust carb

It's not that hard to adjust 2 idle mixture screws to get the idle the best. Too lean and you get a hesitation and backfires when you hit the throttle. Too rich and it hesitates.
Disconnect the throttle cable. With the engine warmed up and running, adjust the idle mixture screws in one at a time until the engine starts to miss, then back it out to best idle. Rev the engine on occasion to keep it cleared out. Do the other screw the same. Keep the idle rpm adjusted to book specs. It may take several times of this to get best results. Once you get it, back each screw out 1/8 turn and it should be good to go. NO, if 1/8 turn more is good, it doesn't mean 1/2 turn is better.
Once you get it in the water, just recheck the adjustment, but it's probably fine.

No $200 tools needed.

 

[achris]

Re: Lambda to adjust carb

Most of the centre riser elbows have a hole cast (and plugged) in them for a sensor (used on the Bodensee engines). You may be able to get your sensor in through that hole. Or, as you say, in the manifold (you have aftermarket, aluminium) right up against the head.

I can't see why that wouldn't work... Good luck and keep us informed of the progress/results.. I have a friend who's going to need a new carb on his 4.3l soon, and I'd love to know the end result of your tuning...

Chris........

 

[achris]

Re: Lambda to adjust carb

It's not that hard to adjust 2 idle mixture screws to get the idle the best. Too lean and you get a hesitation and backfires when you hit the throttle. Too rich and it hesitates.
Disconnect the throttle cable. With the engine warmed up and running, adjust the idle mixture screws in one at a time until the engine starts to miss, then back it out to best idle. Rev the engine on occasion to keep it cleared out. Do the other screw the same. Keep the idle rpm adjusted to book specs. It may take several times of this to get best results. Once you get it, back each screw out 1/8 turn and it should be good to go. NO, if 1/8 turn more is good, it doesn't mean 1/2 turn is better.
Once you get it in the water, just recheck the adjustment, but it's probably fine.

No $200 tools needed.

Don, he's put a 1409 on and needs to tune everything, mains, emulsion tubes, etc..... hence the desire for the sensor...

 

[dubs283]

Re: Lambda to adjust carb

i would think that if you put a performance carb on your engine you would want to tune it for performance not fuel economy

if you want fuel economy, put a two barrel carb on it - or stop boating

as far as setting up the carb, follow don's advice and treat it like a weber (which it is)

 

[90stingray]

Re: Lambda to adjust carb

a vacuum gauge, and reading plugs is the best way to tune your carb imho.

^^^^ bingo!