Need to run valves on a D339 and have not run them on a 4 cylinder before. TIA, Slim
The middle two are on the same "throw", and the outer two are on the same throw. Rotate the engine by hand until you see which one is TDC with the exhaust closing and the intake opening, check the valves on it's pair. Rotate 180 and see which one of the other pair is closing and check it's pair. Another 180 and check the one that was first TDC on exhaust, as it's now on compression. Another 180 and the last one left.
Yep the valve over lap method, works great on all even number of cylinder four strokes. Four cylinder engines are easiest but if you know the firing order of those with more cylinders it's easy to figure out. Say you have a six cylinder with firing order of 1 5 3 6 2 4. Just put the first three numbers over the last three and that tells you which are pairs. 1 over 6, 5 over 2 and 3 over 4. Here is what Cat says for a 3304, I still prefer the "Valve over lap" method as you do one cylinder at a time and are not jumping around to different cylinders, not too bad on a four cylinder engine but with an in-chassis V engine it can be a pain. Only real advantage of the Cat method I see is you don't have to turn the engine as many times: 1. Put No. 1 piston at top center (TC) on the compression stroke. Make reference to Finding Top Center Compression Position For No. 1 Piston. 2. Make an adjustment to the valve clearance on the intake valves for cylinders 1 and 2. Make an adjustment to the valve clearance on the exhaust valves for cylinders 1 and 3. 3. Turn the flywheel 360 degrees in the direction of engine rotation. This will put No. 4 piston at top center (TC) on the compression stroke. 4. Make an adjustment to the valve clearance on the intake valves for cylinders 3 and 4. Make an adjustment to the valve clearance on the exhaust valves for cylinders 2 and 4.
On most engines you can adjust the intake valve when the exhaust valve on the same cylinder is wide open (all the way down) and vice-versa. That way you can bump it around with the starter, marking them when you have them adjusted and not need to bar it over and hunt for TDC or 18 degrees. I have done dozens of different engines that way and found that Mack engines with Dynatard cam are the only ones that won't adjust that way. Since intake valves open immediately after the exhaust closes (and there is slight overlap on some engines), make sure the exhaust is fully open when adjusting the intake. I usually double check and double mark them when I do this. It's by far the easiest and quickest method.