Chevy's have always been notorious for lifter "tick". I wouldn't have thought twice about that. Since you are having a backfire problem, it definitely sounds like you are hanging the exhaust valve open at the time of ignition. You can rule out broken pushrod, since the valve wouldn't open at all. Bent is possible, but not probable since most of the high-revving Chevy's come with hardened pushrods. Hence, they will break before bending.
Does the exhaust have a strong scent of gas when this is happening? If so, it may not be a mechanical problem at all. You may have a dead cylinder electrically and you are pushing raw fuel into the "cats". Check the spark plugs to see if you have a wet or badly fouled plug. Also, if you are pushing fuel into the exhaust, you can just drive it at night, stop and check the color of the "cats". If they are glowing, you are definitely pushing raw fuel out the exhaust, which means that you have a plug, wire, or ignition problem. Fix that before you have to spend alot on new cats and O2 sensors.
If it is not that, I would recommend taking off the valve covers, pulling the coil wire and have one of your "Beer swilling Chevy friends" turn the car over while you watch the rockers go up and down. Take special notice of the valve stem heights (straight edge) to see if you have an exhaust valve hanging low all the time. Also, if this is a high-RPM/deceleration problem, look at all of the springs, inner and outer. You might have one broken and it is "floating". You wouldn't see it at idle, but definitely up above 4000 RPM and coming down from there.
FYI - When you are asking for help from people knowledgeable about Chevy's, try not to insult them at the same time. ;-)
|