Lars:73conv emissions
Thread Starter
Intermediate
Joined: Apr 2005
Posts: 34
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Lars:73conv emissions
lars,
Here is the emissions information from the first and second test.
The standard is as follows:
HC 400 Loaded / 400 Idle
OC 3.75 Loaded / 5.00 Standard
First Test:
HC 191 Loaded / 290 Idle
OC 4.27 Loaded / 5.14 Idle
Second Test:
HC 544 Loaded / 1018 Idle
OC 7.41 Loaded / 7.50 Idle
After the first test I had thought it was the best I could do by myself, that was when I had taken it to a Mechanic. I thought he could dial it in and get the car to pass. Obviously he doesn't know what he is doing. Any suggestions on getting this thing to pass emissions? Thanks for the help.
Here is the emissions information from the first and second test.
The standard is as follows:
HC 400 Loaded / 400 Idle
OC 3.75 Loaded / 5.00 Standard
First Test:
HC 191 Loaded / 290 Idle
OC 4.27 Loaded / 5.14 Idle
Second Test:
HC 544 Loaded / 1018 Idle
OC 7.41 Loaded / 7.50 Idle
After the first test I had thought it was the best I could do by myself, that was when I had taken it to a Mechanic. I thought he could dial it in and get the car to pass. Obviously he doesn't know what he is doing. Any suggestions on getting this thing to pass emissions? Thanks for the help.
Race Director
Joined: Sep 1999
Posts: 11,361
Likes: 383
From: Plano TX
It's running way rich. Make sure the choke is open all the way and the airfilter is clean.
If that checks out adjust the idle mixture leaner. You should turn the idle mixture screws leaner until there is a 50 rpm drop in idle speed. Both screws have to be adjusted equally (turned out the same amount from seated).
If you're not comfortable doing it yourself, find a mechanic that has an exhaust gas analyzer so they can do it correctly.
If that checks out adjust the idle mixture leaner. You should turn the idle mixture screws leaner until there is a 50 rpm drop in idle speed. Both screws have to be adjusted equally (turned out the same amount from seated).
If you're not comfortable doing it yourself, find a mechanic that has an exhaust gas analyzer so they can do it correctly.
Thread Starter
Intermediate
Joined: Apr 2005
Posts: 34
Likes: 0
Originally Posted by zwede
It's running way rich. Make sure the choke is open all the way and the airfilter is clean.
If that checks out adjust the idle mixture leaner. You should turn the idle mixture screws leaner until there is a 50 rpm drop in idle speed. Both screws have to be adjusted equally (turned out the same amount from seated).
If you're not comfortable doing it yourself, find a mechanic that has an exhaust gas analyzer so they can do it correctly.
If that checks out adjust the idle mixture leaner. You should turn the idle mixture screws leaner until there is a 50 rpm drop in idle speed. Both screws have to be adjusted equally (turned out the same amount from seated).
If you're not comfortable doing it yourself, find a mechanic that has an exhaust gas analyzer so they can do it correctly.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
73 -
Do you have any idea what the "mechanic" did to the car? Looks like he must have had the carb apart, because it has been seriously richened up... Did he do a jet and/or rod change as well..?
You're going to need to un-do whatever the guy did. The carb needs to be set up correctly, because it's clearly screwed up right now. I'd pull the top off the carb and check the jetting against the correct specs. You need to check and set up the power piston stop height and the float level. Make sure he didn't replace the float with an aftermarket brass float. If so, you need to get the right float in it. Once you get the carb "un-screwed", you need to go in and knock your timing back: Looks like the guy might have advanced the timing in order to get the HC up that high. Knock the timing back to its factory spec and bump your idle rpm up against the test limit.
Tag me back with any questions.
Lars
Do you have any idea what the "mechanic" did to the car? Looks like he must have had the carb apart, because it has been seriously richened up... Did he do a jet and/or rod change as well..?
You're going to need to un-do whatever the guy did. The carb needs to be set up correctly, because it's clearly screwed up right now. I'd pull the top off the carb and check the jetting against the correct specs. You need to check and set up the power piston stop height and the float level. Make sure he didn't replace the float with an aftermarket brass float. If so, you need to get the right float in it. Once you get the carb "un-screwed", you need to go in and knock your timing back: Looks like the guy might have advanced the timing in order to get the HC up that high. Knock the timing back to its factory spec and bump your idle rpm up against the test limit.
Tag me back with any questions.
Lars
Thread Starter
Intermediate
Joined: Apr 2005
Posts: 34
Likes: 0
Lars,
The mechanic did replace the float with an after market brass float. At this point do you think it would be best to rebuild the original carb or use the one that is on it? The original has not been touched. The car was in storage for several years and it's all gunked up.
The mechanic did replace the float with an after market brass float. At this point do you think it would be best to rebuild the original carb or use the one that is on it? The original has not been touched. The car was in storage for several years and it's all gunked up.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
It doesn't really matter which one you use as long as it's set up right. If he put a brass float in it, it's not set up right and needs to be fixed. Throw that brass float over the fence into your neighbor's yard and get the correct NitroFill float from NAPA. If it's a pre-'75 carb the part number is 2-440. You need to set the float level to .375" and verify the jetting to the correct spec. You then need to fix that timing problem that's screwing up your HC.
Thread Starter
Intermediate
Joined: Apr 2005
Posts: 34
Likes: 0
Lars,
I put the old carb on the car to see if it worked better than the mechanics nightmare. The timing is at 6degrees, and the idle set at 1000 rpm. Here is the readings after the emissions test this afternoon
HC
Loaded 209 Standard is 400
Idle 824 Standard is 400
CO
Loaded 3.64 Standard is 3.75
Idle .29 Standard is 5.00
As you can see the HC is too high at the idle reading, what tweeks can I do to get it under 400?
Once again thanks for your help.
And by the way, you read my mind. I was going to ask you where to pick up the correct float.
Thanks,
73conv
I put the old carb on the car to see if it worked better than the mechanics nightmare. The timing is at 6degrees, and the idle set at 1000 rpm. Here is the readings after the emissions test this afternoon
HC
Loaded 209 Standard is 400
Idle 824 Standard is 400
CO
Loaded 3.64 Standard is 3.75
Idle .29 Standard is 5.00
As you can see the HC is too high at the idle reading, what tweeks can I do to get it under 400?
Once again thanks for your help.
And by the way, you read my mind. I was going to ask you where to pick up the correct float.
Thanks,
73conv
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
73 -
If your initial timing is set up to 6 degrees and you're running your vacuum advance off of a ported vacuum source (not manifold vacuum), here are other items that contribute to high HC:
High HC usually indicates ignition misfire due to fouled spark plugs or a bad plug, bad plug wire, or faulty ignition system component. Replace plugs and wires and check/set dwell. Replace cap & rotor. Gap plugs correctly (.035").
High HC can also be caused by burned exhaust valves (check compression), and lean misfire (check for vacuum leaks: your CO at idle is extremely low, indicating you could possibly have a lean misfire/vacuum leak contributing to high HC).
Lars
If your initial timing is set up to 6 degrees and you're running your vacuum advance off of a ported vacuum source (not manifold vacuum), here are other items that contribute to high HC:
High HC usually indicates ignition misfire due to fouled spark plugs or a bad plug, bad plug wire, or faulty ignition system component. Replace plugs and wires and check/set dwell. Replace cap & rotor. Gap plugs correctly (.035").
High HC can also be caused by burned exhaust valves (check compression), and lean misfire (check for vacuum leaks: your CO at idle is extremely low, indicating you could possibly have a lean misfire/vacuum leak contributing to high HC).
Lars
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Thread Starter
Intermediate
Joined: Apr 2005
Posts: 34
Likes: 0
I am running the vacuum advance off of a ported vacuum source. I pulled the plugs and replaced them, all of them were light gray in color. The vacuum line for the vacuum advance has been replaced along with the lines going to the canister. Should all the vacuum line be replaced? Also do you think the car would pass emissions using your timing tech tip?