Cam Synchro/ TDC/ Rebuild Question

[krh1326]

Hello All,

Real bonehead question. In the proccess of rebuilding my 99 vulcan. Pistons, crank, cam, lifters, cyl heads, timing gears and chain, timing cover and oil pan are installed.

Going for the new synchro at this point.

Crank and cam are still in the 'just installed' position. They have not been rolled, the keyways and marks are still lined up.

0 (tdc) is right on the mark to the right of the crank position sensor.

Is this my TDC on compression or intake stroke? Is this the position that I want to install the synchro??

Yes, I could postpone synchro install until intake, rods and rockers go in, to roll it over to check the for suck or blow at the plug hole, but I am famous, or infamous, for setting distributers 180 out, so I wanted to try to head this off at the pass.

Thanks for any input.

EDIT:

To clarify, I am asking when the timing set is freshly installed, and the timing marks are all lined up, what stroke would the crank be in? I'm trying to figure out, in the factory, when they put these together, the timing marks are aligned. When they drop in the synchro, does it go with the timing set marks still aligned, or do they roll the crank once.

 

[Rearanger]

Is this my TDC on compression or intake stroke?

There are two TDCs, compression and exhaust, which is the same position for the crank. It's only compression when the cam is aligned and connected to the crank pulley that closes both valves to produce compression. On initial setup the crank is just TDC, neither compression or exhaust. The cam sprocket then is aligned to it's mark with crank at TDC for installation of the timing chain. Once you have the cam and crank sprockets aligned and connected you should be at TDCC. Check it by putting your thumb over the spark plug hole and feeling the pressure produced by compression, at that point the marks should align. The cam turns half as much as the crank.

 

[krh1326]

There are two TDCs, compression and exhaust, which is the same position for the crank. It's only compression when the cam is aligned and connected to the crank pulley that closes both valves to produce compression. On initial setup the crank is just TDC, neither compression or exhaust. The cam sprocket then is aligned to it's mark with crank at TDC for installation of the timing chain. Once you have the cam and crank sprockets aligned and connected you should be at TDCC. Check it by putting your thumb over the spark plug hole and feeling the pressure produced by compression, at that point the marks should align. The cam turns half as much as the crank.

Yes. I accidentally wrote compression or intake, what I meant was when cam and crank marks are aligned is it tdc after intake or exhaust?

The timing gears and chain are all installed. When the marks are aligned, crank up and cam down as opposed to one further crank revolution where crank mark is returned to the up position, but the cam mark is also up.

 

[Rearanger]

what I meant was when cam and crank marks are aligned is it tdc after intake or exhaust?

Should be after intake, on compression. Because the cam rotates half as much as crank all the marks will only align on TDCC.

 

[krh1326]

Ah you answered before I could finish the drawing.

This was my question, better organized. Which drawing represents TDC on compression stroke?

 

[Rearanger]

Which drawing represents TDC on compression stroke?

I'm assuming your drawing explains which is which?? But my Haynes says the left drawing, timing marks closest to each other. My Haynes cautions about making sure the oil passage in the camshaft bolt is clear of obstructions. It also describes checking for timing chain stretch.