Double checking my work using the backside valve adjust method

thedude113 · 10-31-2007, 05:57 AM

Gents-

I'm adjusting my valves for the first time. After plenty of research, I've gone down the backside method path. I like the method, but I am having trouble when I double check my work.

My first issue was with tightening the nut and messing up the screw adjustment. First I tried leaving it a little loose and letting the final tighten on the nut close the gap a little more, but that worked like throwing darts at a board blindfolded. The difference between good and too tight seems to be about the thickness of the end of the slot on the screw. I had the best luck when I adjusted the screw with the .0025 gauge in until the gauge would barely pull out, then I held the screw in place with a stubby screwdriver (clamped with a vise grip for some leverage) while I tightened it with the box end of a wrench. The adjstment would back off a hair while tightening and the .0025 gauge would come out easier, while the .003 gauge wouldn't fit. Does anyone have a better way to do this?

Next, I figured out that keeping the feeler gauges oiled up helps them slide in more consistently. Initially I would adjust the intake valve, then do the exhaust, and when I re-checked the intake it would be too tight. There is no way that adjusting one should affect the other one, right? In the beginning, I wasn't oiling up the feeler gauge. At these tiny tolerance, the friction from dry metal on dry metal is enough to make a difference wrt Go/ No Go.

Once I got a complete side finished (240 deg rotations), I went back and double checked all of them. Almost everytime, there would be at least one that needed re-adjusting. It usually needed to be tightened. Why would they change when I came back to them? Was it too loose to begin with, but I'm not realizing it until I re-check it? Or am I not lining up the tick marks exactly and consistently? I have actually checked every valve at least 8 times now. Time is not a factor, so I want to make sure everything is perfect before I button it up. Any recommendations?

930turbo · 930turbo's Garage

Set your crank position to TDC, power stroke on which ever side you choose to adjust first, such as #1. After setting both I&E lash, rotate the crank 240 and adjust #2 I&E lash, rotate the crank another 240 and adjust #3 I&E lash. repeat for the other side starting on TDC power stroke, view it as two separate 3 cylinder engins. Remember, it takes 720 degres rotation to complete a full power cycle. 240+240+240=720. 'hope this helps.

thedude113 · 10-31-2007, 06:47 AM

I did it that way when I set it and checked it, then I double/triple checked it using 120 deg and going back and forth in firing order of all 6 cylinders. I did not focus on setting the tick marks up perfectly, just within a tick marks width of each other. Is the tick mark alignment that critical?

joecrum · 10-31-2007, 08:08 AM

I did my first one a couple weeks ago using the backside method. I had the same problem that when I rechecked most were slightly loose. After the second adjustment, I buttoned it up and didn't check a 3rd time. The car runs stronger and the torque is more pronounced at 3.5k. I hear no valve noise, but the engine seems slightly louder, mechanically. I'm guessing they might all be a little tight, but the car feels great.

I've heard that looser is better than tighter. Is this true??

By the way, I needed to tighten my belt to turn the engine and now my engine runs MUCH cooler!