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Got the Ford 3.8L V6 running Sunday. Finally.
I got back from taking a friend flying at noon and finished up buttoning it up. Here's the background: This is a modified 3.8L V6 with a Northwest Aero PSRU. The engine was completely rebuilt with the block baked, bead blasted and scoured, then bored and honed to fit new 9 to 1 compression ration pistons from Wiseco. The crank was sent out to be turned and new bearings were installed for the crank and con rods. The heads were planed and I needed four new intake valves. New seals, new guides, valves lapped in and 1 to 8 ratio roller rockers with new lifters. New cam per David Blanton's original specs. Regardless his strangeness with horsepower claims, no one found fault with the camshaft specs. No reason to, the design was spec'd out to one of the premier camshaft engineers in Detroit and he got it right. The cam was milled from a solid billet rather than regrinding the original so the original, standard length pushrods could be re-used. New stock Ford valve springs were used. I fabricated a test stand on casters that I can drag into my Tacoma and drive it up into the woods for testing away from civilization. I built it tall enough so that the engine could run with the prop installed. But it wouldn't run. I spent three weeks fooling with it trying to get it running with no success. Finally someone asked if I had any intake suction. That's the one test I had not done. Carb removed, hand over intake opening, crank the engine and nothing. No vacuum at all. I used to be a certified auto mechanic and never misstimed an engine in my life, but I'd misstimed this one. I pulled the timing chain cover off and stared in disbelief. The camshaft was at least 5 teeth away from where it should be. So I reset it and double and triple checked that it REALLY was correct now, scraped off the old gaskets, installed new and buttoned things up. Cranked it with my hand across the intake manifold opening and it tried to suck my hand through the opening. Even after I'd stopped cranking, the suction remained. That was an encouraging sign. By Sunday afternoon I was pouring in hot water (to make the engine a little easier turning over) and ready to try it. Starter switch to on, ignition on, fuel pump on, instruments on and start! Row row row row row... nothing. Flip the throttle in and out a few times: Row row row row... nothing. Recheck timing by cranking the engine with the ignition off and finger in the no. 1 spark plug hole till it blows my finger out indicating it's on compression and then hand turn the engine to TDC and check where the rotor in the distributer is pointing. Hmmm, it's actually off some so I twist the distributer to align it better. Try checking the timing using the timing light and no flashing. Could that be the problem, no ignition? Recheck everything with a test light, all is functioning properly, what's going on here? Oooops, timing light clip has fallen off the battery. I re-attach it and crank the engine and now the timing light is flashing properly. I can now fine tune the distributer to get the timing at 8 degrees BTDC. Obviously, the ignition is working. Ready again, hearing protection on: Row row row... nothing, not a pop. Ok, time for auxiliary starting fuel. Grab the acetylene torch and crank up the acetylene and stick the tip into the carburator with the butterfly valve half open to allow the gas in to the intake manifold. Row row row row... **BAAAARRRRROOOOOOMMMMMM**BRAP BRAP BRAP, it's running. I pulled the tip out and slammed the throttle shut and darned if it didn't continue to run, albeit somewhat roughly, and very VERY loudly. I spent the next half hour fiddling with various adjustments and finally got it running reasnably smoothly, at least at idle and up to 2,000 rpm. But man that thing is *L*O*U*D* loud, and mean sounding. It sure doesn't sound like grandma's Plymouth. I need to quiet that down or I won't be able to take it into the woods and run it without upsetting folks for miles around. Perhaps "Supertrapp" mufflers? Anyway, it's running, the psru is tracking smoothly and this is a milestone. It has a little leak of oil from the front crankshaft oil seal, not sure what's going on with that yet but it isn't severe. I also runs a bit rough when revved up past 3,000 but I'm not sure what's happening there either, I haven't check to see if the timing is advancing. That's another test yet to do. So I'm fairly pleased right now. Next step is to bolt on the prop and run the engine in and then do some long term testing at various power settings. I spent a lot of time modifying the intake manifold per Ford V6 STOL suggestions and specifications to have an engine that will run smoothly at 4,800 rpm but that's with the prop installed. I also custom fabricated the exhaust headers, making each tube exactly 40 inches long precisely to prevent a rough running hard to tune engine. More testing to follow. These tests need to be carefully documented so that the DAR can verify that the engine has been tested. It's important for me too. ;-) Corky Scott |
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