O.K. , the short story is : the valve guides on this 1969 C/10's 250 CID L6 are looser than Madonna's knees plus the intake manifold's PCV fitting is wrong so most of the PCV venting goes directly into the center intake port , fouling the # 3 & 4 cylinders with oil even worse than the wobbly valve guides do ~ it has an irregular miss at the best of time & tune that gets progressively worse with miles , yesterday Jr. & I got stuck in bumper to bumper cross town traffic for an hour of mostly sitting still in gear @ idle so now I have a bad miss all the time , under load , @ idle , all the time ~ I already replaced the brandy new but fouled spark plugs once and I'm lazy to - day so I grabbed a spray bottle and filled it with tap water , drove the truck a few miles to ensure it's 100 % warmed up then I held the throttle to about 3,500 RPM's in neutral and began spraying the water into the carby's air horn ......... As the water gets sucked in the intake and is compressed in the cylinders , it *instantly* flashes to _steam_ and this blows the accumulated carbon off the piston crowns and valves ~ it also sometimes helps clean a fouled spark plug , this time not so much help on the fouled spark plug but it _did_ blow a bunch of carbon out the exhaust and runs markedly better now . The irregular miss is still there , as soon as I can find an undamaged correct manifold set , I'll yank the cylinder head off and have it properly rebuilt , something the Texas Machine Shop couldn't handle apparently . I'll have silicone bronze valve guides installed along with stainless steel one piece valves and hardened seats unless they were done before , doubtful considering the poor work done to the rest of this poor old truck . Stay tuned . To - morrow is the periodic Long Beach Veteran's Stadium Auto Swap Meet , I have to go there and get some new Clay Smith Cam decals , I'll keep a lookout for a good used 194/230/250/292 manifold too , maybe I'll get lucky ~ I passed on a Marine one yesterday for $60 as it wasn't drilled for the PCV valve and I feel that's an important thing , not to be left out nor cobbled up by adding an adapter to the power brake port.... BTW : before you go trying this Farm/Junkyard/Backwoods remedy on your oldie , be aware that water isn't very compressible so adding too much water in volume , to a high compression engine , can *instantly* bend the connecting rods , crack or shatter the pistons and in some cases , crack / explode the cylinder heads .
After The Test Drive I am pleased to announce that the engine once again is as smooth as silk but for idling in gear as the oil sucked past the wobbly valve guides still causes that irregular miss . smokes a bit of blue @ idle too . I may have found an entire fan to tranny 292 CID L6 TakeOut however so if that works out , I'll be in the clover . I got lucky at the Long Beach Veteran's Auto Swap Meet this morning , almost as soon as I walked in , I found the entire stock air cleaner with brackets , tube , hardware and so on , for $25 . I'm still wondering why the exhaust head pipe to manifold joint , won't stay fastened ~ every couple weeks it begins to leak again , I'm afraid to tighten it anymore for fear of snapping off the stud . Maybe I'll double nut it next time .
I've never heard of the water trick before, Nate...will keep that in mind if I ever find myself in need. I would imagine just a light spray will turn to steam pretty quickly...certainly wouldn't want to overdo a good thing...
Steam Cleaning Yep ; Works like a charm , watch the water volume though , a mist works safest . You alls have many neat things I learn but I have a few up my sleeve too ~ I wish I could show you the air blaster I made up ~ I keep it handy when on the road to blow the cab out , not always a place with an air gun but I can always find an old fashioned air chuck to use with this simple tool .
