What is the correct way to decrease the CO?

[pablovent]

Hello ;

I am running the first miles with my Westy 1978 engine code CJ type4 2.0, dual 32-34 pdsit completely rebuilt (stock cam, stock CR, stock carbs) all seals and hose perfect .... In the first emission control the numbers were:

-Idle: HC 145 ppm - CO 6.34
-2.500 rpms: HC 152 ppm - CO 6.56

This numbers show aparently a fuel mixture too rich.....Before the emission control the carburetors were tuned without a machine (best idle run), and the timing with strobo light 5º BTDC iddle - 30º BTDC max at 3200 rpms.

For decrease the CO numbers and carburetors tune up work, will be necessary to reduce the jets size?.

Thanks...

[williamM]

before doing much, I would go over the settings on you linkage,run the timing back a few degrees, get the motor broke in a bit and make sure your chokes are completely opening.

My fiat wouldn't come down on CO so we finally ended up dropping a cat into the exhaust- never did find out what was wrong.
_________________
some days I get up and just sit and think. Some days I just sit.

opinion untempered by fact is ignorance.

Don't step in any!

[pablovent]

[williamM]

any spec's on what the carbs are now- got pics of your set up.
_________________
some days I get up and just sit and think. Some days I just sit.

opinion untempered by fact is ignorance.

Don't step in any!

[pablovent]

55 idles, 140 mains, stock airs 155, 93 RON fuel....Sparks plugs looks very clean white and light brown....stock central air cleaner, stock style muffler, unfortunately I can not use a wideband because the exhaust system.

[williamM]

It will be a while but I have a few of those, so can see what hey actually ran, there maybe a section in the "Technical" section here, or in the "without guesswork" books - probably from 73, as a 2.0 in USA T-4 motor had FI system.
_________________
some days I get up and just sit and think. Some days I just sit.

opinion untempered by fact is ignorance.

Don't step in any!

[pablovent]

Yes...this is the problem, my CJ type4 engine code not sale in USA with carbs.....stock jetting info 52,5 idles, 135 mains, 155 airs....

MY engine run really fine...the HC numbers are too small maybe will increase this numbers when decrease the CO...Just only I look for other similar tune up experiences!

[Abscate]

Failing to salute in front of the Corporal...
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.ssS!

[raygreenwood]

If this is a brand new engine.....do not worry about CO and fine tuning yet. Synch the carbs and make sure its neither excessively rich or lean.

Yes....the cam and lifters break in in 20-30 minutes.....but I have found the rings can take upwards to a few thousand miles of running to REALLY get sealed. Ray

[Tram]

[kevineo]

Drop yours, install a buddies motor that passes. Re-install yours and break it in properly. Unfortunately skirting the law is the sane move. Do not, Do not try to get exempted! When your denied you will be flagged for life.

[pablovent]

My preference is the best air/fuel mixture for the first miles after rebuilt work...the emission control was only for this reason.....just I want not run too lean and not run too reach....Now is summer in my country and run too hot is very risky for a heavy bus.....thanks

[scubaseas]

[scubaseas]

You may want to look at these two links.

http://www.ratwell.com/mirror/interro/techgas.html


http://web.archive.org/web/20060307212134/http://www.interro.com/techgas.html#anchorone
_________________
Al

08/1970 T2a Westphalia owned since 1980

ASE Master certification. 50 years pushing a wrench
Retired

[SGKent]

does Chili have smog tests on cars that old?
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“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[pablovent]

[quote="scubaseas"]

[pablovent]

[scubaseas]

[Wildthings]

I think you will have a hard time getting the HC dialed in until you get the engine broken in. I would try retarding the timing by a few degrees as that is very easy to do and is very readily reversible.

Assuming you have the carbs synched well:

-your idle mixture is controlled by the idle jet and the idle screw.

-low throttle opening mixtures are controlled primarily by the idle jet

and

-larger throttle openings mixtures are controlled by the main jets.

[SGKent]

turn the idle mixture screw out on each carb just until the engine runs smoothly then slowly turn each one in until the RPM begins to drop quickly, then turn it back out 1/8th turn. Then sync the carbs and test again. If the engine hesitates when you step on the gas, open the idle mixture screws a 1/8 turn more. Set your timing so it is at 30 - 31 degrees before TDC at 3500 - 3800 RPM with any hoses off the distributor then put them back . See how that tests. If the CO is still too high turn the idle mixture screw in 1/16th turn at a time and try again. Make sure that ALL vacuum leaks are found and fixed before you start this.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin