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Pre roller cam 1986 and earlier 100k, age becomes a factor with the nylon silent mesh cam. Little plastic pieces in drain pan during oil change is a sign to change timing set.
1987 and later roller cam engine uses roller chain which can last 200k plus.
What is the average life of a timing chain on an early C4? Is there warning signs when the chain is worn?
If you put a socket and johnson bar on your crankshaft pulley bolt, move it back and forth. It will move the crankshaft, and when the timing chain slack is taken up, it will start to move the camshaft and valvetrain. When there is a few degrees of rotation taking place between the crankshaft moving and the camshaft moving, that shows the amount of timing chain slack. It's very noticeable, like a clunk of resistance as you push on the bar.
LiveWire!, I hate to pick nits, but I believe you mean a breaker bar. A Johnson bar is a 6' long wooden pry bar, usually hickory with a steel wedge on one end used to lift heavy objects like a piece of machinery. Also known as pry bars, these provide the leverage you need to lift a large load onto a dolly. They are often used in pairs to lift each end of a load so a dolly can be slid underneath.
That's the difference between Colorado and Ontario, Canada. To us, a Johnson bar is exactly what I described, to crack bolts with a socket before putting a smaller ratchet on the socket. The bar you described is simply a pry bar to us. I used to carry one in my truck, forever. 40 year heavy construction electrician, retired.
No big deal. Like the difference between a pop (us) and a soda (you). Thanks for the chuckle.
I did not feel good with this thing in my engine. After I discovered it I put a Melling dual roller in and it does not make any noise anyway.
Who did the placebo test and found this quieter and by how much I wonder. This was around 140,000 so it was lasting.
I would not want to be suspecting that thing every time I have a problem. Just better to do away with it. Get a double roller, and it is a great way to freshen the front up.
You have to drop the oil pan in front, you don't really have to remove it. I would do that ask me why I know. Got an earful when I had the Corvette mech change my oil pan gasket. FTW
I do not believe that early C4's have a cam timing gear. There are people on here saying that early C4's have the nylon cam year. I'd like to see a picture of an actual cam gear from an 85.
I have copies of the 1953-1982 and 1984-1996 Corvette parts and illustration catalog.
These catalogs list part #340235 for 1967-82, and 1984-86 Corvettes with 305, 327, or 350 CID engines.
I changed the timing chain on my 1995 K1500 Chevrolet Pickup 350 w/ 117K miles due to 15 degrees of slack. The cam gear installed in my truck was all metal and had "340235" stamped on it (same part # as 67-86 Vettes). So based up on this, 1967-1986 small blocks had a steel timing gear.
The part # changes to 10088127 for 1987-1991 Vettes, which is also a steel gear. (1987 is when they switched to a roller cam)
The parts book list part # 330814 and 330815 for 396, 427, and 454 engines. These cam gears had Nylon. Strange that the big blocks had the nylon.
With that said, my 1995 K1500 Pickup timing chain had experienced a lot of stretch with 15 degrees of slack with only 117K miles, so I would change any small block timing chain near 100K miles.
