The Stovebolt Site Forums The Shop Area Engine Shop Degrees from top dead center

A dumb question probably, I have been working on the correct timing for my 1960 235 engine. With my light I can easly find top dead center. My problem is I have to guess at the degrees. If it's guesswork how far should I allow for a degree? I am using a good inductive timing light.. Is there a mark I am missing? Also, I have been told that my 235 should be set at 4 degees before TDC. is this correct?

Thank you for any help.

Don

Are you using the original flywheel?

If you are, there should be a small ball/bb embedded in the forward outer/upper face of the flywheel. That can be viewed through the hole in the forward face of the clutch housing on the starter side of the engine. That bb is the static-timing mark. Note that different year flywheels, and different year engines, have different timing settings/marks.

You mean piston movement down from TDC in inches?
It's really small for the first few degrees (like any other engine), and also corrupted by the piston pin offset.

Nominally, 1° is .0004" (not even 1 thousandth)
5° .010"
10° .038"
15° .086"
20° .152"
25° .235"
30° .335"

You'd be amazed at the number of times I've seen this: "The piston’s position relative to the top of the cylinder is the stroke length ÷ 180, times the number of degrees".

Thank you guys, that helps. In the past on old cars I have guessed, but this engine seems a little more fussy. I don't know if the flywheel is original. It was bought as a rebuilt long block.

Don, without actually mounting a degree wheel on the front of the crankshaft, it's an educated guess as to where timing marks are going to be on a particular engine. Even the engines with more accessible timing marks than a stovebolt can have timing errors due to manufacturing tolerances between the crankshaft, flywheel, bellhousing, etc. Does your timing light have a delay-flash feature which allows you to dial the timing flash back to zero with the engine running? If so, all you would need to do is find a true TDC position by using a positive stop on the #1 piston. Someone else just discovered that the positive stop rod inserted into the spark plug hole needs a bend in it to actually be able to reach the piston crown. If you need information on making the stop fixture and doing the checking procedure, drop me a PM- - - -it's a pretty detailed process.
Jerry