Ok, I have a problem starting my 272 it will pause just at the start of a compression stroke.<o></o
I have set the timing chain and sprockets, 12 pins between timing marks. Engine turns over very easy without the plugs, as soon as I put one plugin the engine will pause on that cylinder. If I put all of the plugs in it cranks very slow and will barely turn over. <o></o
Too much initial advance. Back off the timing a bit and see if it improves.
Unless you know that the damper is good, you cannot rely on it to set the timing. Over time, the damping mass can move and the timing marks are on that mass. The fix is a new or rebuilt damper.
You can still loosen the distributor and adjust. Once it runs, go back and set it where it needs to be if you can.
Another thing, The marks on the gears were at the 3 o'clock position when viewed from the front of the motor (pointing to the oil pump side of the motor), correct? Some books illustrate this incorrectly which results in incorrectly installed gears.
Yes, I have set the timing marks @ 3 o'clock with 12 pins between the two marks. It's got to be the strangest thing I have come across. When I remove all of the plugs it turns over great. For a example, I will remove all of the plugs except #1 cylinder and then turn the engine over, it will pause at #1 cylinder. This same thing happens on all cylinders it will pause on the cylinder that has the plug. It acts like there is to much compression. When the piston just starts it's move up to TDC it will Pause.
If you aren't familiar with changing the timing advance setting just remove the coil wire from the coil to the distributor, that will illuminate the question of it possibly being to far advanced. If it spins freely it's a timing issue, if it remains the same the problem is else where.
A little more info would help.
You didn't say if this is a new motor or an old one that you just replaced the timing chain?
Do what hiball says, first. That will rule it out.
To adjust the timing, loosen the distributor clamp bolt and turn the distributor. I believe it is counter clockwise to retard the timing. Make very small changes until it turns over and starts. You won't have to move it a whole lot to put it too far in the other direction, where the opposite will happen - it turns over very easily but still doesn't start.
If that doesn't work, there are other ways to determine the approximate relation of the distributor to the crank without relying on the timing marks if you are unsure of the damper's condition.
However, if it ran before the timing chain replacement and the distributor was not moved, it should be close to where it needs to be. Did it run?