1988 ZX n/a 5 speed (not that it matters for this question).
Am getting ready to pull right cylinder head, looking for exhaust leak. For my own info, I performed
compression test and started doing leak down test. That prompted me to think I should know
exactly how to put any given cylinder at TDC. So I made up a little table to help me visualize it. (Yeah,
I know I could just watch the distributor rotor).
I'm assuming the crankshaft goes 180 degrees to get a piston from TDC to BDC. i.e. each of the 4 strokes is completed in 180 (crankshaft) degrees. Two complete rotations of the crankshaft get a piston
back to exactly the same state. Also tells me 720 degrees / 4 strokes = 180 degrees per stroke.
Secondly, I read and observed that the distributor rotates at 1/2 the rate of the crankshaft. And
since there are 6 cylinders and the distributor rotates 360 degrees for a full rotation, it must be
360 / 6 = 60 degrees between each distributor contact. And that the firing order is 1,2,3,4,5,6.
See the attached JPG image. The table seems to work out perfectly. Noting that each piston is at TDC (beginning the power stroke) 120 crankshaft degrees after the previous piston. Also true going from piston #6 to piston #1 .
The problem is ... in my Haynes manual, on page 68 (in the lower left corner of the page), it says
that cylinder 1 and cylinder 6 are at TDC at the same time. Obviously, if #1 is beginning the
compression stroke, #6 must be beginning the intake stroke.
According to my diagram, at 0 degrees (#1 at TDC) , #6 is NOT at TDC. It is nearing the end of the
power stroke.
The Haynes manual sounded pretty definite. So I figured I must be wrong and confused. Is my table completely wrong ???
Am getting ready to pull right cylinder head, looking for exhaust leak. For my own info, I performed
compression test and started doing leak down test. That prompted me to think I should know
exactly how to put any given cylinder at TDC. So I made up a little table to help me visualize it. (Yeah,
I know I could just watch the distributor rotor).
I'm assuming the crankshaft goes 180 degrees to get a piston from TDC to BDC. i.e. each of the 4 strokes is completed in 180 (crankshaft) degrees. Two complete rotations of the crankshaft get a piston
back to exactly the same state. Also tells me 720 degrees / 4 strokes = 180 degrees per stroke.
Secondly, I read and observed that the distributor rotates at 1/2 the rate of the crankshaft. And
since there are 6 cylinders and the distributor rotates 360 degrees for a full rotation, it must be
360 / 6 = 60 degrees between each distributor contact. And that the firing order is 1,2,3,4,5,6.
See the attached JPG image. The table seems to work out perfectly. Noting that each piston is at TDC (beginning the power stroke) 120 crankshaft degrees after the previous piston. Also true going from piston #6 to piston #1 .
The problem is ... in my Haynes manual, on page 68 (in the lower left corner of the page), it says
that cylinder 1 and cylinder 6 are at TDC at the same time. Obviously, if #1 is beginning the
compression stroke, #6 must be beginning the intake stroke.
According to my diagram, at 0 degrees (#1 at TDC) , #6 is NOT at TDC. It is nearing the end of the
power stroke.
The Haynes manual sounded pretty definite. So I figured I must be wrong and confused. Is my table completely wrong ???