BlueBull
02-13-2013, 08:04 AM
I believe this is a tricky one.
My CSB406 with Brodix IK200 heads, a (too) mild comp hyd.roller (050" duration 218/224), headers, performer air-gap, Holley 750vac and 10.5:1 CR has a VERY strong exhaust smell. I check the spark plugs frequently but they look perfect. When I start the engine and try to make some maintenance my eyes gets wet and my clothes absorbs the bad smell. I can honestly tell that I have not checked the fuel mix ratio but the engine runs good. Anyhow, I tried to re-jet 2-3 sizes down but the result was a less responsive engine, especially on higher rpm;s. The car is a convertible and when idling or slow driving the fumes can be sensed in the car. I also once removed the heads and the combustion chambers look fine and the top of the pistons show some evidence of a good swirl.
I have tried some different carburators as dubbelpumpers, vac. different sizes but no change. The engine dont consume any oil and have no visible smoke. I can tell there is still a problem because the mileage is bad - 13mpg.
I also have a 1968 454 LS6 corvette where I installed a previous used 750 DP from the 406 and the smell here is competely different, more normal, smells more well burnt. The milage on this engine is much better despite the engine is bigger, about 15-16mpg.
I realize it's not easy to give a good feedback on this input but maybe the problem itself is familiar to some of you.
Appriciate any help.
/Thanks
My CSB406 with Brodix IK200 heads, a (too) mild comp hyd.roller (050" duration 218/224), headers, performer air-gap, Holley 750vac and 10.5:1 CR has a VERY strong exhaust smell. I check the spark plugs frequently but they look perfect. When I start the engine and try to make some maintenance my eyes gets wet and my clothes absorbs the bad smell. I can honestly tell that I have not checked the fuel mix ratio but the engine runs good. Anyhow, I tried to re-jet 2-3 sizes down but the result was a less responsive engine, especially on higher rpm;s. The car is a convertible and when idling or slow driving the fumes can be sensed in the car. I also once removed the heads and the combustion chambers look fine and the top of the pistons show some evidence of a good swirl.
I have tried some different carburators as dubbelpumpers, vac. different sizes but no change. The engine dont consume any oil and have no visible smoke. I can tell there is still a problem because the mileage is bad - 13mpg.
I also have a 1968 454 LS6 corvette where I installed a previous used 750 DP from the 406 and the smell here is competely different, more normal, smells more well burnt. The milage on this engine is much better despite the engine is bigger, about 15-16mpg.
I realize it's not easy to give a good feedback on this input but maybe the problem itself is familiar to some of you.
Appriciate any help.
/Thanks