Alpine951

I'm trying to do a leakdown test. From what I know if both the timing mark on the top of the bell housing lines up at so does the mark on the cam sproket on my 951 then #1 piston is tdc. How dO I get the others to tdc? Is #4 at tdc when #1 is? Someone told me turn crank 360 degrees from #1 tdc and then #2 and #3 are at tdc? If this is correct how do i determine crank turned exactly 360 degrees?

GlenL

You want each piston at TDC and on the compression stroke.

After getting #1 aligned at TDC with the cam at the alignment point, check the leakdown. THen rotate the crank 180 degrees and you'll be at TDC on the compression stroke for the next piston in the firing order. (cam turns 90 degrees) Repeat for other two pistons.

Alpine951

GlenL,

How do i know I am at 180 degrees from #1 tdc. If I rotate 360 degrees there is a mark through the top of the bell housing but none on the cam sprocket. i am assuming that will be tdc for #3 so I think i am Ok with that. Determining what 180 degrees from #1 tdc and #3 tdc is the issue. I put a white mark on the crank pulley when it was at tdc #1. I turned the crank so that the white mark was 180 degrees by eyeballing it. At the same time i put a stick in the #2 while I was doing this. depending on how I orient the stick in the hole it might stop moving upwards or still move upwards. I am having trouble getting #2 and #4 tdc.

Dmitry S.

Remember the firing order. When you turn the engine 180 degrees clockwise from #1cyl TDC, you are now at TDC on the next cylinder IN THE FIRING ORDER, not numerically. Can't remember it off the top of my head, but it's stamped into your cam tower.

GlenL

I watch the crank to see how much turning is done. Putting a mark oppostie from the 0 degre mark on the flywheel (or a pulley) as you've done would be good for helping with that.

The firing order is 1-3-4-2. Each piston is at TDC on the compression stroke 180 degress after the one before it. (So 4*180=720 or two complete rotations for a four-stroke engine.)

If you set the engine at TDC for #1 (0 mark on crank) and the marks on the cam are aligned, that's TDC for compression on #1. Rotate the engine 180 degrees and it'll be TDC on compression for #3. Rotate 180 degress more and the 0 mark on the flywheel shows up in the window and piston #2 is at tDC on compression. Then 180 more and #2 is at TDC.

Alpine951

Misread the haynes. Firing is 1342. OK. I guess I have to eyeball 180 degrees. I just remembered the piston goes in the direction of bottom drivers side to top passenger side from when i did the head gasket. So taking this into considereation if I had a thin stiker like a wood skewer even if the piston was at tdc i could still stick the stick in more because the top corner of the piston was higher than the bottom top corner.