Running rich, need to reduce CO !
08-11-2010, 07:00 PM
#1
Running rich, need to reduce CO !
When I got my car inspected today the CO levels were a little more than double the "allowable" amount. I know that it's due to the engine running rich and wanted to see if anyone had suggestions as to how I could get a more complete burn inside the combustion chambers.
Limit for tests is 1.2, Actual is 2.63 ( idle ) and 2.66 @ 2500RPM. ( 70's motors put about 1.5 - 2.0 for reference)
Details:
Engine, block 88 LO3
Heads, 416 305 CI mild porting
Cam: 87 305 TPI
Exhaust, L69 manifolds / Y-pipe, 4-bolt cat, flowmaster back
Computer / Emissions, None
Carb, Edelbrock 1406 (Stock jets ?)
Plugs, Bosh Platinum
EGR, None
Engine has about 200 miles on it since it was re-build.
Since the idle and 2500 RPM CO numbers are pretty close I believe the idle set screws on the carb are probably fine. ( I've read a little higher CO at higher RPM's is expected.) This leads me to believe that some type of "overall " adjustment would be needed so that these readings will both drop & remain close to each other.
First question: Engine timing...... The LO3 block/heads/cam required 0 degrees of initial timing. The 87 305 TPI Cam required 6 degrees by the book. The engine is currently set to 7 degrees of initial timing and runs great . I am 'off a tooth' but that simply turned the distributor and should not effect air/fuel. Should I turn it forward (or back) a couple of degrees ?
Second: I'm guessing that the carb still has it's original jets installed. How do I properly determine what jets will lean out the mixture correctly ? ( I've never needed/wanted to re-jet a carb. ) How can I tell what Jets are in the carb when they are taken out ?? How will I know what Jets to re-install ?? I have no way to monitor the air fuel mixture right now, any advise on a testing tool or best gauge for that task ? ( I'll need some way to check the mix after adjustments )
Third: The Cat. It really seemed to be in real good shape and had all it's guts still inside it; but I have no idea how old it is or how well it works. NOT looking to adjust/swap/remove the existing cat !
ANY insight is appreciated ! The car still passed inspection because it was registered as an antique, but the state still requires it to go up on the Dyno machine anyway. I am not too concerned with the high CO count - but I imagine that I will get better performance and will use less fuel if I can lean this sucker out a little !
Thanx in advance !
Limit for tests is 1.2, Actual is 2.63 ( idle ) and 2.66 @ 2500RPM. ( 70's motors put about 1.5 - 2.0 for reference)
Details:
Engine, block 88 LO3
Heads, 416 305 CI mild porting
Cam: 87 305 TPI
Exhaust, L69 manifolds / Y-pipe, 4-bolt cat, flowmaster back
Computer / Emissions, None
Carb, Edelbrock 1406 (Stock jets ?)
Plugs, Bosh Platinum
EGR, None
Engine has about 200 miles on it since it was re-build.
Since the idle and 2500 RPM CO numbers are pretty close I believe the idle set screws on the carb are probably fine. ( I've read a little higher CO at higher RPM's is expected.) This leads me to believe that some type of "overall " adjustment would be needed so that these readings will both drop & remain close to each other.
First question: Engine timing...... The LO3 block/heads/cam required 0 degrees of initial timing. The 87 305 TPI Cam required 6 degrees by the book. The engine is currently set to 7 degrees of initial timing and runs great . I am 'off a tooth' but that simply turned the distributor and should not effect air/fuel. Should I turn it forward (or back) a couple of degrees ?
Second: I'm guessing that the carb still has it's original jets installed. How do I properly determine what jets will lean out the mixture correctly ? ( I've never needed/wanted to re-jet a carb. ) How can I tell what Jets are in the carb when they are taken out ?? How will I know what Jets to re-install ?? I have no way to monitor the air fuel mixture right now, any advise on a testing tool or best gauge for that task ? ( I'll need some way to check the mix after adjustments )
Third: The Cat. It really seemed to be in real good shape and had all it's guts still inside it; but I have no idea how old it is or how well it works. NOT looking to adjust/swap/remove the existing cat !
ANY insight is appreciated ! The car still passed inspection because it was registered as an antique, but the state still requires it to go up on the Dyno machine anyway. I am not too concerned with the high CO count - but I imagine that I will get better performance and will use less fuel if I can lean this sucker out a little !
Thanx in advance !
Thread
Thread Starter
Forum
Replies
Last Post
