Timing Chain Alignment in 5.7L - Chevrolet Forum - Chevy Enthusiasts Forums

Timing Chain Alignment in 5.7L


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  #1  
Old  August 23rd, 2006, 12:16 AM
Timing Chain Alignment in 5.7L

Hey I have what should be a simple question about a 1982 Corvette.

On a 350 Cubic Inch (5.7L) V8, timing chain sprockets be aligned?
Each sprocket (one on the crankshaft, one on the camshaft) has a small mark on it.
Most service manuals show the camshaft mark at the bottom 6 o'clock, and the crankshaft mark at the top 12 o'clock.
So that the two points are very close together and point at each other.

HOWEVER, the 1982 GM Service Manual has a diagram and it points the camshaft mark at the top.
So that the marks on both sprockets are at 12 o'clock.

The GM manual is the only book I've seen that has it positioned like that.

Does anyone know which is correct?

  #2  
Old  August 23rd, 2006, 12:56 AM
  • Join Date: Jul 2006
    Posts: 504
RE: Timing Chain Alignment in 5.7L

Any that I have seen regardless of make or model have been dots together. When you took it apart were they together? If I remeber right in your other post you had not touched the timing chain yet, right? And it did run where it was, right? If so then if they were together or close that is how they would go. It is also the factory engine too, right?, just modified to a card setup with the computer out/disconnected? You might be able to ask a dealer or even go to a local shop and see what their books say. If I had to guess I would say together, but you don't want to run it to far off as you can destroy valves and pistons.

  #3  
Old  August 23rd, 2006, 1:42 AM
RE: Timing Chain Alignment in 5.7L

Well I am replacing the timing chain because the old timing chain slipped.

It slipped was pretty much half way between 6 o'clock and 12 o'clock.

Since i didn't see it until after it slipped, i'm not sure where it is supposed to be.

Thanks

  #4  
Old  August 23rd, 2006, 9:57 PM
  • Join Date: Jul 2006
    Posts: 504
RE: Timing Chain Alignment in 5.7L

That does make it a bit harder. That would keep it from running. If you don't have it on yet I have one more question/suggetion. I know some if not all of the 80's Chevys had a type of plastic gear (just the teeth) on the cam shaft, if you have that it is more than likely pretty worn down if not stripped and it slipped on that. If so if you look at the way your engine turns you can tell which way it went, but how far is a better question. I just thought of that. If it made more that a 1/2 rotation on a slipped gear that wouldn't help. You may want to turn your engine by hand and see if you hear anything that dosen't sound right or feel right. If it slipped to much you could have a bent valve.

  #5  
Old  August 25th, 2006, 10:00 AM
RE: Timing Chain Alignment in 5.7L

Hang on a moment here... we're talking about a small block chevy engine right???
The crankshaft sprocket has half as many teeth as the camshaft sprocket, right???
The crankshaft spins 2 times for every time the camshaft spins
Doesn't that mean that the crankshaft sprocket will be in the 12 o'clock position at the same time the camshaft is in the 12 and the 6????
That clears you from doing any mechanical damage to the pistons and valves (basic engine timing)
So for nobody has mentioned ignition timing which would be the real question here...
last time i installed a distributer I had to turn the engine over by hand to see when the intake valve closed... next TDC is whereI would start to install the Dist
I could have looked to see the marks on the chain but The front cover was on

  #6  
Old  August 25th, 2006, 6:46 PM
  • Join Date: Jul 2006
    Posts: 504
RE: Timing Chain Alignment in 5.7L

I'm sorry I was thinking to hard. Your right.


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