66 Thunderbird, rebuilt 390 (couple of years ago). I noticed that on my distributor the #1 coil plug is not pointing to the front, but is pointing to the back. Engine still works and runs, but does that mean that maybe they installed the camshaft 180' off? Or is something else amiss?
The distributor was changed from points to a Petronix distributor.
I have taken the petronix out turned the engine 180' over, changed the coils to what is supposed to be the right position, reinstated the distributor and it does not work
Any thoughts?
Camshaft 180' off?
Moderator: redstangbob
Re: Camshaft 180' off?
So it worked, you changed it, and now it doesn't work?
I suppose if you really want to know what is going on, remove the valve covers and watch the valve open and close events as you turn the crankshaft. Then you will know what is going on (without the hassle of removing the timing cover). You can also rock the crank back and forth and look for excessive slop to see if the chain is stretched and needs replacement.
Alternatively, you can put it back like you found it and it will probably run again. A lot less work, but it depends on what you are trying to accomplish.
I suppose if you really want to know what is going on, remove the valve covers and watch the valve open and close events as you turn the crankshaft. Then you will know what is going on (without the hassle of removing the timing cover). You can also rock the crank back and forth and look for excessive slop to see if the chain is stretched and needs replacement.
Alternatively, you can put it back like you found it and it will probably run again. A lot less work, but it depends on what you are trying to accomplish.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
Re: Camshaft 180' off?
jtschung, so I did put it back like I found it, the engine still runs, my question was, could it be 180' off? Is there a way to find out if the camshaft was installed incorrectly? Does it make a difference if it is 180' off and still works? Would there be any issues with it down the road?
Thanks
Thanks
Re: Camshaft 180' off?
Yes, there is a way to see if it is off. Take off the valve cover over Cylinder #1.
On a 4 stroke engine the crank spins twice for every time the cam spins once. So when the timing marks are at 0, the #1 piston is either at the top of the exhaust stroke (exhaust valve open) or compression stroke (exhaust valve closed). So put the crank at 0 and both valves closed, then remove #1 spark plug and check if the piston is at TDC by putting a bit of straightened coat hanger wire down the hole, at TDC the wire should go down into the hole regardless of which direction you turn the crank. If the wire goes up, keep turning in that direction until it stops and reverses. That point where it reverses is TDC, that will tell you how far the 0 mark is off. If both valves are still closed, then the cam is probably close enough.
Now that you are at TDC on the compression stroke, remove the distributor cap and look at where the rotor is pointed. If the rotor is 180' off, this can easily be fixed by pulling out the distributor, turning the rotor to where it is supposed to be and then dropping it back down into the hole. The drive gear is helical, so it might take a few tries to get it just right. Then you are going to have to set the timing again. With the vacuum advance plugged, initial timing should be about 15' BTDC.
On a 4 stroke engine the crank spins twice for every time the cam spins once. So when the timing marks are at 0, the #1 piston is either at the top of the exhaust stroke (exhaust valve open) or compression stroke (exhaust valve closed). So put the crank at 0 and both valves closed, then remove #1 spark plug and check if the piston is at TDC by putting a bit of straightened coat hanger wire down the hole, at TDC the wire should go down into the hole regardless of which direction you turn the crank. If the wire goes up, keep turning in that direction until it stops and reverses. That point where it reverses is TDC, that will tell you how far the 0 mark is off. If both valves are still closed, then the cam is probably close enough.
Now that you are at TDC on the compression stroke, remove the distributor cap and look at where the rotor is pointed. If the rotor is 180' off, this can easily be fixed by pulling out the distributor, turning the rotor to where it is supposed to be and then dropping it back down into the hole. The drive gear is helical, so it might take a few tries to get it just right. Then you are going to have to set the timing again. With the vacuum advance plugged, initial timing should be about 15' BTDC.
1966 Thunderbird Convertible (Emberglo / White-Emberglo)
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
Modified 428 - stroked, rollercam, aluminum top end, headers
Livermore, CA
