It's not the valvetrain...
04-20-2007, 12:21 PM
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It's not the valvetrain... This is on a stock 01 LS1:
I was at the road course at the end of last season doing some hot laps. I got a little too ambitious and bounced off the 6800 limiter a couple times on a straight. A puff of smoke came out of the exhaust and it lacked a little bit of power so I did a cool down lap and headed in. The idle isn't normal- it seems there is a rythmic more powerful puff of exhaust every rotation of the crank. Also the car bounces at idle now that clears up over idle RPMs. Since then, I've driven the car about 30 miles and nothing's changed. Oil pressure seems fine,so I assumed I had broken something in the valvetrain, but after taking it apart, I discovered that everything still looks brand new and checks out okay. I'm thinking maybe the cam or main bearings, but they should have gotten worse in the 30 miles, right? Having the heads off, I also check to see if any pistons were loose- (conrod, piston pin worn) and they are all still tight with no play. The cylinder walls look good so the rings should be in good shape. When I drained the oil, there was some fine particles on the drain plug that felt like that fine grey graphite lube. Does anyone have any suggestions or thoughts? Also, if you spin a bearing, how long do you have before it gets really chewed? A couple miles? More? Thanks, Andrej.
I was at the road course at the end of last season doing some hot laps. I got a little too ambitious and bounced off the 6800 limiter a couple times on a straight. A puff of smoke came out of the exhaust and it lacked a little bit of power so I did a cool down lap and headed in. The idle isn't normal- it seems there is a rythmic more powerful puff of exhaust every rotation of the crank. Also the car bounces at idle now that clears up over idle RPMs. Since then, I've driven the car about 30 miles and nothing's changed. Oil pressure seems fine,so I assumed I had broken something in the valvetrain, but after taking it apart, I discovered that everything still looks brand new and checks out okay. I'm thinking maybe the cam or main bearings, but they should have gotten worse in the 30 miles, right? Having the heads off, I also check to see if any pistons were loose- (conrod, piston pin worn) and they are all still tight with no play. The cylinder walls look good so the rings should be in good shape. When I drained the oil, there was some fine particles on the drain plug that felt like that fine grey graphite lube. Does anyone have any suggestions or thoughts? Also, if you spin a bearing, how long do you have before it gets really chewed? A couple miles? More? Thanks, Andrej.
