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why would you want to check TDC on #4?
All of your engine timing is set on #1 and #4 can't change on it's own without breaking the crank , a bent rod would change the piston height when it's at TDC but not WHEN it's at TDC.
Last edited by akwheeler; May 13, 2020 at 02:36 PM.
I'm pretty sure that on a 22R engine number 1 and number 4 are both up at the same time.
Likewise, number 2 and number three are both up at the same time.
This^
Sorry guys the post had less to do with #4 specifically and more to do with my concern about TDC (on any cylinder) putting the timing mark where its at.. could my timing chain have skipped or something?
Sorry guys the post had less to do with #4 specifically and more to do with my concern about TDC (on any cylinder) putting the timing mark where its at.. could my timing chain have skipped or something?
It could have, but you still need to check it the right way, with #1 cylinder on the compression stroke (valves closed and cylinder building pressure) at TDC.
That is the ONLY cylinder that will be on the compression stroke with the valves closed when you get to TDC where the timing mark lines up and you have the distributor lined up at the #1 spark plug wire.
If #1 cylinder is verified at TDC (compression stroke or not) with a straw down the spark plug hole and the timing mark doesn't line up you have issues with the harmonic balancer or the woodruff key on the crank. I don't think a borescope is a very good way to check TDC either, and the straw method leaves some doubt since you can turn the crank a little ways without detecting movement of the piston. But when the straw stops moving your timing mark should be pretty close and if you were to mark your balancer and keep rotating the crank until you detect movement in the straw and make another mark your EXACT TDC should be right in the middle of those two marks
Since you can't bend a crank without breaking it the #4 cylinder should also line up at the same time, but why stretch yourself out to check #4 at the back of the engine?
There are a few degrees of what we can call dwell (at the top of the arc it's hard to perceive the piston top moving), but not ten degrees. Assuming your not turning the crank backwards, if you turn the crank backwards there is a delay before the cam moves that varys a bit based on the health of your tensioner and residual oil pressure as the chain transitions (somewhere there should be a video of me demonstrating this) from memory mine is about five degrees.
Long story short.
don't turn the crank backwards.
Check your timing, cam dowel and crank keyway at 12, and replace your balancer if it sounds.
May 13, 2020 | 05:46 AM
