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Discussion Starter · #1 ·
I had to pass a tail pipe emissions test before I could get
a plate. First time through I failed! Did a bit of checking
and found my secondary idle jet was not seated. I also
checked to see what jets where installed.

Primary = main 125, air 160, idle 50
Secondary = main 130, air 170, idle 60

This carb came from my parts car, so I don't know
what the stock weber jets are.These seem much leaner
than what others are running.

Could these be so lean to cause damage?
Could I put 130 & 140 mains in without changing airs?

Garry
 

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What were the numbers you got from your test? HC, CO and NOX.....

Was it just an idle test or a load (dyno) test?

Sounds like the carb in your possession may have been jetted for high altitude at some time.

Bob
 

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Discussion Starter · #3 ·
The test is done on what "looks like" a dyno. First they
do a loaded test at a max of 59 MPH. Then a idle test.
You also have to pass a visual on your gas cap. The
readings are...

Loaded HC in PPM - Reading 244, Max allowed 400
Loaded CO in % - Reading 1.02, Max allowed 4.20

Idle HC in PPM - Reading 265, Max allowed 400
Idle CO in % - Reading 4.75, Max allowed 5.50

The NOX is not tested on the older cars.

It does look like the idle could be leaned a bit.
The idle mix was very sensitive with the secondary jet
leaking. There is more adjustment now between rich and lean.

It seems to run real good but this is my first Opel
so I don't have any prior experience. Without help
from these forums I would still be up on jack stands.
 

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Shoot for 1.25% to 1.5% CO at idle and 2.25 to 2.5% CO at light throttle loads, but about 4% at full throttle loads. At 1% under load you are risking engine damage plus you're leaving a lot of power 'on the table'.

Bob
 

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Discussion Starter · #5 ·
I'm going to change the mains to 130 primary and 140 secondary and see how that feels.

Thanks for the feedback.

Garry
 

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Discussion Starter · #6 ·
I forgot to add that it is a stock 1973 except for...
-No EGR anymore
-Weber of course
-Pertronics
-Slightly advanced timing
 

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Mains and "cold air"

RallyBob said:
Shoot for 1.25% to 1.5% CO at idle and 2.25 to 2.5% CO at light throttle loads, but about 4% at full throttle loads. At 1% under load you are risking engine damage plus you're leaving a lot of power 'on the table'.

Bob
AMEN to that! I'd try 140 primary and 150 secondary mains and leave the rest alone. You'll still easily pass the emissions test, but you'll rediscover some of that "power you're leaving on the table" now!

If you're using that little flat rectangular filter on top of your carb, let me strongly urge you to replace it with some sort of "cold air" package, either modified stock or some sort of aftermarket setup. There are numerous threads about doing this on this site.
 

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Coolant

garrymc said:
I'm using the stock filter with the modified adapter. Like in the pictures.

Garry
Have you changed your coolant mix to 1:2 (33%) or 1:3 (25%) and gone to a 160 deg T-stat yet? I would definitely consider it for the Phoenix area where you live, at least the next time around. Cools much more efficiently with higher percentage of water in the mix!
 

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Discussion Starter · #10 ·
I changed to 140 mains on both and it feels ok. Seems to have better low
end grunt. I'll put a 150 in the secondary when I find one. I was concerned
that it was so lean a valve could get fried. Glad I changed them.

I like the quick warm up from a 180 therm. and run 50/50 on the antifreeze mixture. So far the temp. gage is just a little right of center.

Garry
 

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garrymc said:
I changed to 140 mains on both and it feels ok. Seems to have better low
end grunt. I'll put a 150 in the secondary when I find one. I was concerned
that it was so lean a valve could get fried. Glad I changed them.

I like the quick warm up from a 180 therm. and run 50/50 on the antifreeze mixture. So far the temp. gage is just a little right of center.

Garry
OOC, are you running stock "joined" intake/exhaust manifolds? :confused:

Regardless, with a 160 T-stat and 33% mix, it'll warm up just as quickly but run half a bar left of center on the temp gauge . . . much better for engine in AZ or TX heat! T-stat opening temp really has nothing to do with how quickly an engine warms up, rather just up to what temperature it does warm up to.

BTW, the GT temp gauge center mark is 194 deg F (90C)! :(
 

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Discussion Starter · #12 · (Edited)
tekenaar said:
OOC, are you running stock "joined" intake/exhaust manifolds? :confused:

Regardless, with a 160 T-stat and 33% mix, it'll warm up just as quickly but run half a bar left of center on the temp gauge . . . much better for engine in AZ or TX heat! T-stat opening temp really has nothing to do with how quickly an engine warms up, rather just up to what temperature it does warm up to.

BTW, the GT temp gauge center mark is 194 deg F (90C)! :(
194 is too hot. I'll be changing to a 160 for sure (at least in the summer).

Thanks!
 

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SW temps

garrymc said:
194 is to hot. I'll be changing to a 160 for sure (at least in the summer).

Thanks!
I agree. For anywhere in the Southwest, 194 or more IS too hot. :cool:
 

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I may cause a little H & D here, Gary and/or Keith you can put this wherever you think it needs to go, but here's my take on the thermostat. My Clymer's manual, which I will presume got the information from the Opel Manual, states the normal operating temp of the engine is 180-189 degrees. It is a given that the radiator is suspect in its' efficiency. The actual cooling process in any engine is primarily done by the oil flowing through the head, then transferring the heat to the exterior of the water jacket cooling passages in the head. The water that passes at the valve seats/guides is turned to steam momentarily by the combustion heat and steam doesn't cool anything very well. Also the normal operating temp of the oil is around 240 degrees, maybe even higher. Now back to the thermostat. The sole purpose of the thermostat is to restrict flow until the temperature of the outflow from the head reaches the setting of the thermostat, then it opens fully and does not restrict flow at all, until the temperature goes below the setting then it will start to close, then open again as the temp increases again. Eventually it will modulate until a happy medium is reached, not fully open or fully closed. In a good cooling system that poses no problem and is the way it's supposed to be. Now, all that being said, here's some garbage thrown in. The radiator is partially plugged, and the fluid has not been cooled enough to have a good drop in the temp when it gets to the head, so the water heats up more than the thermostat setting and it goes full open, absolutely no restriction to flow through the radiator. So there is no appreciable cool down time for the fluid in the radiator and it gets hotter and hotter. If you have a low temp thermostat the coolant heats up faster because the thermostat is designed that way and the coolant exceeds the thermostat setting and never slows down in the radiator. IMHO, the higher the thermostat setting, the longer the coolant will stay in the radiator to be cooled down by the restricted flow. Even then, the system may be partially plugged and will still reach max setting on the higher rated thermostat. Then for sure a cooling system repair will be needed, but with the restricted flow of the higher set thermostat, there may be sufficient time to cool the coolant in the radiator to prevent overheating. I have seen first hand, folks take the thermostat out of the engines in the high deserts of CA and New Mexico, and overheated their engines because there was no cooling time in their radiators, the coolant went in hot and came out just a few degrees cooler, but definitely not cool enough to overcome the generated heat in the engine. They put a high temp thermostat in and the overheat problems went away. JMTCW.
 

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Just saw this thread....

A couple months ago I was messing with my carb (idle jets) when I installed a rebuilt engine to make sure it idled smooth and passed emissions. My results were:
HC (under load - approx 2500 rpm) 339
HC (idle) 176

CO (under load) 1.18
CO (idle) 2.99

Would I also benefit from 140 (primary) and 150 (secondary) mains?? I have no idea whats in there. I have to remove the top of the carb to find out what the mains are, right? Also.....any suggestion on the air jets?

Also....I run a 160 thermostat with a recently "rodded(?)" radiator (50/50 mix) and my gauge rarely even gets as high as the middle mark....not bad for an old car in southern Nevada in the summer.

I just purchased an orig. air box for my car to replace the little weber filter...whats the best adaptor to use on top of the carb?

I know.....lots of questions but any and all help appreciated.

Mike
 

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Mileage . . .

garrymc said:
Just did the second fuel fillup. I'm getting about 28 mpg with 140 mains.
Uh, does that mean you're happy?!! :rolleyes:
 

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Just looked at the main and air correction jets on my 32/36.

Primary Main - 130
Air Correction - 170

Secondary Main - 150
Air Correction - 180

Given that the CO (during my emissions test) at approx. 2500 rpm (not under load...in neutral) was 1.18% does anyone have any suggestions on a better combination of jets??? Im not sure whether to increase the main to 140 and leave the rest alone or maybe go 160 and 170 on the air corrections and leave the mains alone. If it matters...the altitude here is about 2100 feet.

Thanks.
 
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