Stretched Timing Chain Diagnosis
07-10-2004, 11:32 AM
#2
Le Mans Master
You can take the distributor cap off, the rock the crank pulley each direction. The If the chain is stretched then the rotor will have a dead spot between the directions. How much is too much? I really don't know but if there is a long dead area it probably meas the chain has stretched.
07-10-2004, 11:32 AM
#3
Race Director
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Timing chain stretch easily diagnosed
Rotate engine clockwise by crank pulley. Then pull cap off distributor....and move crank pulley CounterClockWise - slowly. If the chain has any stretch at all, the distributor rotor will not move right away.
If you move the crank pulley at all, and don't see the rotor move, the chain has stretched.
If you move the crank pulley at all, and don't see the rotor move, the chain has stretched.
07-10-2004, 02:13 PM
#5
Team Owner
Thread Starter
If you saw my Edelbrock thread I am trying to track down a backfire on rev up. I will re-look at the timing today but it seemed fine last week at 10 degrees. What spawned the timing chain notion is a ringing/rattling at the front of the engine at cold start-up. It disappears as the engine warms. I'll fight with the car this afternoon.
07-10-2004, 03:09 PM
#6
Burning Brakes
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Did not read the Edelbrock thread. Assuming you have hyd lifters, one of them might not be pumping up correctly (backfire on rev up). Noises from the engine can sometimes reflect off various components and trick you. Carefully using an engine stethescope sometimes helps. After a friend rebuilt a Pontiac engine for his Tempest, a loud sound came from the engine at idle on up. Using a stethescope, and some trial and error, it turned out to be his new aftermarket dipstick rubbing against the crank.
Is this a freshly rebuilt engine? There could be a clearance issue that goes away when the engine starts. If it's an engine with some mileage, it could indeed turn out to be a loosening timing chain.
Is this a freshly rebuilt engine? There could be a clearance issue that goes away when the engine starts. If it's an engine with some mileage, it could indeed turn out to be a loosening timing chain.
07-10-2004, 05:37 PM
#7
Team Owner
Thread Starter
This is not a new engine. I fooled with the timing today for three hours and it will not run right at any setting. Idle is rough at 800rpm and it stalls when I put it in Drive. I set up the distributor last week at TDC at #1 so that is OK. So unfortunately it looks like a flat-ride to a professional and $s. My patience has run out.
