Is the stick/dowel in the sparg plug hole the best way to get 2,3, &4 to tdc?

[951527]

I am trying to do a leakdoen on my 951. #1 is at tdc based on the timing mark at the top of the bell housing and on the cam sprocket. Haynes manual says that for every 180 degree rotation of the crank the next piston will be at tdc. The motor is in the car. I can eyeball 180 degrees by putting a mark at the top of the crank pulley when #1 is at tdc and just eyballing when it is 180 degrees. Some have told me to stick a dowel in the spark plug hole and when the dowel stops rising the piston is at tdc. I didn't have a dowle but I had some wooden barbecue skewers. They are about 1/3 as thin as a pencil. The problem I was having is the plug hole is somewhat perpendicular to the top of the piston. Because of this its possible to slide the skewer across the top of the piston. Speaking of a pencil, do I need something thicker than the skewer I have , like a pencil, and just make sure it is touching the top most part of the top of the piston? Any helpful advice is greatly appreciated. I would imagine that the slightest amount of rotation would pull the valves off the seats and not provide accurate numbers. I guess if I get good leakdown %'s on 2,3, and 4 then it worked but if I get bad %'s then i am wondering if I just didn't have 2,3, and 4 at tdc.

[ae1969]

I just use a long screwdriver.........

You can easily tell when you have reached TDC. JUst go back and forth at the top and you will be able to tell what the highest point is.

[Gear Dog]

I used a dowel for the first one then marked it with a sharpie. What I did was push it up against the cylinder wall to get a consistant reading. for the other 3 I just put it against the wall and turned the crank until I hit the mark.

[Razorback1980]

It sounds like using your skewers is dangerous as they are pretty small and if they break...what if a piece gets caught below the spark plug hole inside the cylinder. You may have to pull the head to get it out. A long screwdriver works as well as ae1969 mentioned, just be careful not to get it in a bind and scratch something but I've done that many times and it works okay. I think the dowel is the best instrument of choice as it doesn't scratch and it's strong enough to not break. But if you don't have one, I would go with the screwdriver. What you can do is use a dowel/screwdriver to find tdc and then use a straight edge to draw a mark across the crank pulley and another reference indicator and then you know exactly where tdc for that cylinder is. If you are off just a little, the valves will not be open but the compression amount will be off because the air won't be fully compressed but the leak test will still provide almost accurate numbers. Of course the higher the compression the faster it leaks off, but you won't be far enough off to make much of a difference.

[951527]

OK. Well then after I get the wife and daughter on a plane to FLA next Sunday for school vacation its me and the car again together all alone!!! FWIW the reason I am doing this is I was using a lot of oil last year, smoked alot on boost at the track, and the oil pan started leaking so I was thinking the pan was getting pressurized. Compression was #1-130, #2-117 (!!), #3-130, #4-130.

[bryanthompson]

A guy on the 914club.com site got a chopstick stuck in there not too long ago... was one of the funniest threads around. I remember one suggestion was something like, "just flip the car over and shake it out."

[Zero10]

Yeah, but 914's are light enough you can do that, plus they're air cooled, so you're not swimming in antifreeze when you do that