Dauntless V6 valves not seating
I have encountered a problem I have never seen before on my 225 V6, the valves won't seat when I tighten the rocker shaft stands down all the way.
A little background here:
I bought this Jeep about 2 1/2 years back, and within weeks had torn it down to do a rust repair and repaint on the body. The PO told me the engine had been rebuilt by a shop for him and had low mileage since then. It seemed to run fairly well, although the carb had no working choke on and it would occasionally backfire back through the carb. As far as I could tell it ran on all 6 cylinders. I never did do a compression check on it when it was still in a complete Jeep.
So for the last 2 years or better it has been sitting mostly inside the garage. I cleaned up the engine and repainted it, and it has been idle until recently, when I began putting all the accesory items back on it with the intent to restart it.
I cranked it with the plugs out to pre-oil the bearings before trying to start it, and it was probably a good thing. I could not get any oil to come out the pump until I opened up the oil pump and stuffed vaseline in the oil pump gears. This worked to get the oil pump to pull prime. I cranked a little more until the new oil filter filled up and I started getting oil at the rocker shafts. I figured I could put in the plugs and wires, and before I put fuel in it I cranked it again just to hear the compression.
Here is where I noticed a problem: the engine was obviously not making compression on all the cylinders. I did a compression check with the finger in the plug holes because I couldn't find the 14 mm adapter for my compression tester, and found that only 4 of 6 cylinders had compression. #4 and #6 were completely dead.
After checking the rocker arms for those cylinders with the cylinder on TDC, I noticed that there was no clearance between valve tip and rocker arm. I loosened the rocker shaft stand bolts a couple of turn and cranked it again, and those cylinders now had good compression.
So I started doing some research. I searched here on the forums for any similar problem, and only found an old thread from 2008 by DaveFL that sounded like he had something similar to mine but never posted a resolution.
The FSM showed the spec for the valve installed height, but I have no way of accurately measuring this. I looked at the pushrod length, but again have no way to accurately measure these. The rocker arm shaft assemblies are obviously fresh replacements, the hardened tip inserts on the rocker arms have no perceptible wear, nor do the ball ends of the pushrods show any wear yet. I looked at the hydraulic lifters, and they look practically new.
So my best guess now is that the rebuild shop may not have set the installed height on the valves correctly. I have pulled the heads back off the engine, and pistons and cylinders also look like very low mileage wear.
Does anyone have a suggestion for a knowledgeable machine shop around Sacramento CA? I need to find one that knows these Buick V6 engines, and get to the bottom of this.
'70 CJ5 the Yellow Barn Find. V6, T14, D18, Warn OD, D27, Flanged D44 W/Trak-Lok, 4.88.
'69 CJ5, still undergoing a rebuild. V6, SM465, D18 W/TerraLow, D27, D44 W/LockRite, 4.88
'66 CJ5, a Pile O'Parts. F134, T90, D18, D27 W/Powr-Lok, D44 4.27.