help, no 120 degree marks for valve adjustment

[jwakil]

I found some other postings with similar issues but didn't quite find a solution. I'm doing my first valve adjustment and noticed that my crankshaft pulley doesn't have the 120 and 240 degree grooves for making sure cylinders 6, 2 etc. are at TDC. I was thinking of making my own rough marks by measuring the circumference and then splitting it into 3. I was just wondering how accurate I have to be. I heard there was quite a range of degrees where the cylinders were at TDC.

[2.70Racer]

Both intake and exhaust valves are closed during the compression stroke and firing stroke.
This means for at least 100 degrees before and after TDC compression both valves are closed.
Therefore if you mark the 120 and 240 marks with any kind of reasonable accuracy you will be able to adjust the valves.
It is easy to check the rocker arms to be sure they are riding on the base circle, (the low part of the cam lobe).
Take your time and remember the basics.

[Alex1411]

Me ,too!Need help!

[jwakil]

Thanks, I made my own marks. It was actually pretty hard to measure the pulley down there. I ended up measuring the smaller hub between the pulley for the fan and the pulley for the AC, and then drew the mark up to the bigger pulley. I took a lot of pain to get it as accurate as I could, probably overdid it but next time I don't have to worry about it.

[Two Rivers]

Turn the engine till the intake valve on the apposed cylinder just starts to open about one millimeter or so. The cylinder you want to adjust will be ready.

[Drisump]

I assume the TDC line is there. You can accurately mark the pulley by measuring the diameter of the pulley, multiplying that length by 3.14 and obtaining your circumference from there. Cut a piece of masking tape that length and make marks at 1/3 and 2/3 of the length. If you can semi accurately apply the tape to the outer portion of the pulley (starting at TDC), apply. If you can't, you'll have to take your fan belt off. Mark those points with a center punch, hack saw blade or cut off wheel on a grinder right through the tape and you won't have to mickey mouse again. Just my .02. Cheers

[diverdan]

You could take the distributor cap off and note the position of the rotor for #1 when the tdc mark is visible on the crankshaft damper and just use the the rotor possition to determine the firing time or TDC for the other cylinders. Its accurate enough for the valve adjustment. I have often used a draftsmen's 60 degree triangle (180 degrees minus the 60 degrees = 120 degrees. I mark with paint or a greas pencil. Good luck.

Dan