I bought my 1991 Z28 Three years ago and it has almost always blown a good 6-10 second puff of smoke out the exhaust on initial start up, usually when its cold. The car now has over 100,000 miles on it and it doesn't loose any oil between changes. I thought I read some where that these cars have cold start injectors. Could this be un burnt fuel? I have been dealing with this since I bought it 25,000 miles ago, but now I want to start doing mods, but not ready for a total tear-down. Any Idea what this could be? If it is valve seals, wouldn't the problem get worse over time insetad of staying the same for so long?

 

what colour(color) is it?

 

1991 Z28s do not have a cold start injector. I think 89 was the last year? Anyways your problem is the valve stem seals.What happens is when the car is parked small amounts of oil drip past the seals on the valve and build up on top of the piston. When the car starts the oil is burned. Dont worry its usually like a drip on a cylinder or two and dont worry too much cause almost every Camaro has had this problem. Mine did and it does get a little embarassing at times. Im not sure if there is an upgrade for better seals or not. I ended up rebuilding my old tired motor and slapping on some aluminum heads at the same time. I took my new heads to a HiPo engine shop and had them dissasembled and reassembled and checked out while they adjusted the valve seat pressure for my cam. I told them my concerns about the seals and they took care of it with what they say they will guarantee no leaks.

 

Thanks for the info. The color is whiteish blue.