exhaust emission values?

[gummisko]

what is the optimum CO value?
for performance and MPG wise??

in sweden im alowed to have a CO of 3.5

on my latest MOT i had a CO of 0 and a HC of ~1500


i have a MA12 engine with MA10 inletmanifold+carb and a 4-2-1 exhaust manifold

 

[frank]

gummisko

our limit is 3.5 too (pre cat)
a k11 with both cats is typically .006 co and 11ppm hc (200hc limit)
so your co looks very good and your hc looks high (maybe unburnt fuel from the bigger jet or the 4-3-1 ?

 

[gummisko]

i want to know if its better to have a higher CO value?
because if i raise the CO, the HC goes down....
what is the perfect mixture??

 

[frank]

gummisko

i presume, high hc = rich = more power
low hc = lean = less power, more mpg

 

[gummisko]

i read somwewe on this forum that a CO of 1.9 is a good start...
where do i adjust the CO??

 

[Ed]

CO is ajusted by a screw on the side of the carb. CO of 0 and HC of 1500 is odd. CO and HC go up side by side (generally speaking) i.e. unburnt fuel = high HC and as the fuel has not burnt ususally thats due to a lack of oxygen hence hich CO as well.

 

[frank]

gummisko

could your high HC be from a missfire or oil consumption ?

 

[Ed]

Or incomplete combustion due to incorrect ignition timing.

 

[JStone]

Mine's running at 0.165% CO and 181ppm...

Also discovered that the mixture screws on my carb are farked.

 

[gummisko]

it does missfire a bit...

yesterday i checked my ignition with a strobe light and it was 20 BTDC
i was in a hurry and made a fast adjustment and got it up to 8 BTDC ...
and when i tried to get it closer to XTDC it died...
so i need to do?:
-raise the idle?
-and continiue adjusting the ignition?
-and then raise the CO?

a friend told me it could be dirt in the carb??

 

[frank]

gummisko

20deg is a lot of advance at tickover , i,m surprised it was,nt pinking
i think the mixture screw will only affect the low rpm, and you might need different jets to optimise the mixture at higher revs
and iirc your 1.0 carb has a bigger mainjet anyway

 

[whipit]

Think your probably find that they just didn't measure the CO, don't see how it would be zero. Guessing this was a legal test like our MOT's?

 

[gummisko]

yes this was at my latest MOT ("besiktning" in swedish)

my previous 1.0 engine had over a HC of ~3000 and a CO of 0.
its the same carb, so im guessing i brougt the problem with me to the 1.2...

i will try to adjust my CO today...i got a CO meter at my work...

 

[whipit]

It may be the same carb but the engines are quite different. Just don't think there measuring mate.