Exhaust emissions

[Daniel Brunner]

I need to lower my exhaust gas emissions (HC value) otherwise I‘ll not be able to get a registration for my car in my country.
I know its not a big deal in the US but here it is. My HC value is way too high to be exactly it‘s 3x above the standard here. I have a spicy cam in my motor so there‘s maybe a bit of an overlap. Is it possible to tune the carburetor with some very lean squirters to avoid as much unburned gas getting out of my exhaust? I have a Holley 4160 4barrel
Maybe someone has a good advice here I really don’t wanna swap my cam.

 

[Scott Engelhardt]

Hydrocarbons are unburned fuel molecules, timing, and jetting would be a great place to start. I would also make sure all of my ignition components are good.

 

[Billccm]

Are emissions tested only at idle or running loaded on a dyno?

If it's idle only, retard the timing will reduce the hydrocarbon emissions at idle. It leads to higher combustion temps. This is what the factories did in the mid-60's. They also went to ported vacuum sources to reduce the timing advance from engine vacuum at idle.

Another trick is to introduce a small vacuum leak to lean out the system. Pin holes in vacuum lines work.

If you are tested under load on a dyno I'm afraid there's not much you can do to help other than lean the carb.

 

[Daniel Brunner]

Yeah, it was tested from idle to 2500rpm under no load

 

[mpgmike]

Even at 2500 RPM, no load conditions are greatly affected by the idle circuit in the carburetor. You could lean it out some easily with the idle mixture screws. Secondly, if you haven't done it already, an electronic ignition conversion with a more powerful coil can better burn the fuel you're using. These are the "low hanging fruit" things you could start with.

 

[Budnicks]

Main Jets (in the front metering block) & power-valve,
could seriously affect it
*air-bleads 'if it has any replaceable type', up on top of the carb
bigger jets there is leaner, it's air not fuel up there
or emulsion jets on/in the metering block (inside the float-bowls)
you could buy an aftermarket 'metering block', like from Quickfuel etc.
to do most all the necessary tuning, emulsion & power valves jets

a lot of it isn't for the novice, but easy enough
(Maybe buy a book like David Vizards, SA216 CarTech
"How to Super Tune & Modify Holley Carburetors")

The accelerator pump discharge nozzles "squiters" layman's terms
go to a white cam on the throttle lever maybe too
(or the least aggressive ramp)
Squirters don't really affect it as much,
unless your working/pumping the throttle peddle
(*if it has a bigger accelerator pump like a 50cc, put a 30cc pump in it)
you could go to a smaller front 'squirter' size, like A 28-31 'MAYBE'
(discharge nozzle, on a vacuum carb, you don't have one in the rear)
But;
it will have flat spots/hesitations when on the peddle, but be a lil' leaner
from idle or at a stop light etc., taking off it will suck be a dog

Ignition timing can help too, a hot ignition/coil to help burn that fuel
like a MSD CD multi-spark (if they even allow aftermarket ignitions there)
but you'll still need to find the spot they want to pass it
retard the ignition like 10* initial, at idle (with the vacuum adv. disconnected)
maybe 32* total
will put heat in it, help burn fuel, be a dog too down low too
(It probably with a better cam/aftermarket, needs more like 18*-21*s initial at idle
36* w/the mechanical advance all in)
& stock style distributor, with the vacuum advance hooked up,
stock & all in it will be like 50*s total at 2,500-3,000rpm,
unless you've limited the mechanical advance
www.4secondsflat.com FBO ignition
again not really for the novice tuner either

*Idel mixture screws, on the side of the metering block/s
(again a vac. carb only has a front metering block)
can or will play a part too, up-into 'tip in of the throttle' 500-750 rpm past the idle,
not just at idle
*lean it out, turn the screws in, both the same amount, to lean it
but so it will still run worth a crap...

Good luck

 

[Don Frelier]

Motor swap?

 

[Daniel Brunner]

Main Jets (in the front metering block) & power-valve,
could seriously affect it
*air-bleads 'if it has any replaceable type', up on top of the carb
bigger jets there is leaner, it's air not fuel up there
or emulsion jets on/in the metering block (inside the float-bowls)
you could buy an aftermarket 'metering block', like from Quickfuel etc.
to do most all the necessary tuning, emulsion & power valves jets

a lot of it isn't for the novice, but easy enough
(Maybe buy a book like David Vizards, SA216 CarTech
"How to Super Tune & Modify Holley Carburetors")

The accelerator pump discharge nozzles "squiters" layman's terms
go to a white cam on the throttle lever maybe too
(or the least aggressive ramp)
Squirters don't really affect it as much,
unless your working/pumping the throttle peddle
(*if it has a bigger accelerator pump like a 50cc, put a 30cc pump in it)
you could go to a smaller front 'squirter' size, like A 28-31 'MAYBE'
(discharge nozzle, on a vacuum carb, you don't have one in the rear)
But;
it will have flat spots/hesitations when on the peddle, but be a lil' leaner
from idle or at a stop light etc., taking off it will suck be a dog

Ignition timing can help too, a hot ignition/coil to help burn that fuel
like a MSD CD multi-spark (if they even allow aftermarket ignitions there)
but you'll still need to find the spot they want to pass it
retard the ignition like 10* initial, at idle (with the vacuum adv. disconnected)
maybe 32* total
will put heat in it, help burn fuel, be a dog too down low too
(It probably with a better cam/aftermarket, needs more like 18*-21*s initial at idle
36* w/the mechanical advance all in)
& stock style distributor, with the vacuum advance hooked up,
stock & all in it will be like 50*s total at 2,500-3,000rpm,
unless you've limited the mechanical advance
www.4secondsflat.com FBO ignition
again not really for the novice tuner either

*Idel mixture screws, on the side of the metering block/s
(again a vac. carb only has a front metering block)
can or will play a part too, up-into 'tip in of the throttle' 500-750 rpm past the idle,
not just at idle
*lean it out, turn the screws in, both the same amount, to lean it
but so it will still run worth a crap...

Good luck

Thank you!

 

[66 Sat]

Your best bet is finding out what the inspector drinks and buying him a bottle of it...

 

[mrhemi]

Main Jets (in the front metering block) & power-valve,
could seriously affect it
*air-bleads 'if it has any replaceable type', up on top of the carb
bigger jets there is leaner, it's air not fuel up there
or emulsion jets on/in the metering block (inside the float-bowls)
you could buy an aftermarket 'metering block', like from Quickfuel etc.
to do most all the necessary tuning, emulsion & power valves jets

a lot of it isn't for the novice, but easy enough
(Maybe buy a book like David Vizards, SA216 CarTech
"How to Super Tune & Modify Holley Carburetors")

The accelerator pump discharge nozzles "squiters" layman's terms
go to a white cam on the throttle lever maybe too
(or the least aggressive ramp)
Squirters don't really affect it as much,
unless your working/pumping the throttle peddle
(*if it has a bigger accelerator pump like a 50cc, put a 30cc pump in it)
you could go to a smaller front 'squirter' size, like A 28-31 'MAYBE'
(discharge nozzle, on a vacuum carb, you don't have one in the rear)
But;
it will have flat spots/hesitations when on the peddle, but be a lil' leaner
from idle or at a stop light etc., taking off it will suck be a dog

Ignition timing can help too, a hot ignition/coil to help burn that fuel
like a MSD CD multi-spark (if they even allow aftermarket ignitions there)
but you'll still need to find the spot they want to pass it
retard the ignition like 10* initial, at idle (with the vacuum adv. disconnected)
maybe 32* total
will put heat in it, help burn fuel, be a dog too down low too
(It probably with a better cam/aftermarket, needs more like 18*-21*s initial at idle
36* w/the mechanical advance all in)
& stock style distributor, with the vacuum advance hooked up,
stock & all in it will be like 50*s total at 2,500-3,000rpm,
unless you've limited the mechanical advance
www.4secondsflat.com FBO ignition
again not really for the novice tuner either

*Idel mixture screws, on the side of the metering block/s
(again a vac. carb only has a front metering block)
can or will play a part too, up-into 'tip in of the throttle' 500-750 rpm past the idle,
not just at idle
*lean it out, turn the screws in, both the same amount, to lean it
but so it will still run worth a crap...

Good luck

All good approaches here. If you can swing it, the MSD ignition definitely will help. With the emissions as well as performance. The box can be hidden if necessary. Not mentioned yet is installing the highest temperature thermostat available just to get through the test, then replace with the normal. As mentioned previously higher combustion temps help lower emissions. One of the reasons newer vehicles run with 200+ degree T stats.
Another potential aid would be the dreaded ethanol blended gasoline if available to you, but that will only help if it does not skew the carb jetting the wrong way. Nothing higher than E10.

 

[RiverRaider]

Not an answer, more of a question would different fuel help a vehicle pass the test. Would a high mix of ethanol in the fuel help?

 

[dadsbee]

Do the old GM thing to cut emissions, they ran an air pump to dilute it. Get a big air blower, feed it into each exhaust pipe and see what comes out the back.

 

[Don Frelier]

Do the old GM thing to cut emissions, they ran an air pump to dilute it. Get a big air blower, feed it into each exhaust pipe and see what comes out the back.

I had the same thought.
But I was serious about the engine swap.