Noob with cam question
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Teching In
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Noob with cam question I just picked up a 2000 Formula M6. The previous owner had a Texas Speed Cam installed by what he called a reputable shop and dyno tuned. I have noticed that the car's exhaust smells like it is running rich at idle. I have zero experience with LS cars. I do have some experience with fuel injection and computer controlled cars/tuning. I have owned a Buick Grand National for about 20 years and have done all the tuning on this myself with a piggy back system that is wired into the stock ecm. Other than the cam, the car has an SLP lid, SLP exhaust, and long tubes. My question is, is this the nature of the cam that is in the car or is this a tuning or other issue? The car runs awesome and the dyno sheet that the old owner gave me with the car says it put down 412HP on a dyno-jet. Any help would be much appreciated.
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I just picked up a 2000 Formula M6. The previous owner had a Texas Speed Cam installed by what he called a reputable shop and dyno tuned. I have noticed that the car's exhaust smells like it is running rich at idle. I have zero experience with LS cars. I do have some experience with fuel injection and computer controlled cars/tuning. I have owned a Buick Grand National for about 20 years and have done all the tuning on this myself with a piggy back system that is wired into the stock ecm. Other than the cam, the car has an SLP lid, SLP exhaust, and long tubes. My question is, is this the nature of the cam that is in the car or is this a tuning or other issue? The car runs awesome and the dyno sheet that the old owner gave me with the car says it put down 412HP on a dyno-jet. Any help would be much appreciated.
Overlap is when both the intake valve and the exhaust valve is open at the same time. During "overlap" un-burned air and fuel from the intake tract can pass straight through to the exhaust. This can account for and/or contribute to the smell of raw fuel coming out of the exhaust.
A factory camshaft can have 30 degrees or so less overlap than your aftermarket performance camshaft. So, they pass considerably less un-burned air and fuel into the exhaust.
At 6 degrees of overlap, I would think a really good tune and well functioning catalytic converters should be able to control the fuel smell. If it were mine, I would have the tune checked by someone sharp with such issues.
Thread Starter
Teching In
Joined: Dec 2016
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As camshafts get larger in duration, they tend to have more overlap in general. Your 228/232 camshaft on a 112 degree lobe separation has abut 6 degrees of overlap at .050" of lifter lift. This means it probably has around 60 degrees of overlap in seat timing.
Overlap is when both the intake valve and the exhaust valve is open at the same time. During "overlap" un-burned air and fuel from the intake tract can pass straight through to the exhaust. This can account for and/or contribute to the smell of raw fuel coming out of the exhaust.
A factory camshaft can have 30 degrees or so less overlap than your aftermarket performance camshaft. So, they pass considerably less un-burned air and fuel into the exhaust.
At 6 degrees of overlap, I would think a really good tune and well functioning catalytic converters should be able to control the fuel smell. If it were mine, I would have the tune checked by someone sharp with such issues.
Overlap is when both the intake valve and the exhaust valve is open at the same time. During "overlap" un-burned air and fuel from the intake tract can pass straight through to the exhaust. This can account for and/or contribute to the smell of raw fuel coming out of the exhaust.
A factory camshaft can have 30 degrees or so less overlap than your aftermarket performance camshaft. So, they pass considerably less un-burned air and fuel into the exhaust.
At 6 degrees of overlap, I would think a really good tune and well functioning catalytic converters should be able to control the fuel smell. If it were mine, I would have the tune checked by someone sharp with such issues.
