My buddy is about to fire up his 50 Ford w/ freshly rebuilt Flathead. His cam was reground and has new lifters. The machine shop guy that put it together said it doesn't need to be broken in like a normal flat tappet cam. Is this true? He said just fire it up and drive it like normal. This is (Obviously) my first flathead rebuild and never would have thought this was true. Any other insight on its first fire I should know about?
Well, flatheads need much weaker springs and have very direct straight valve action, so stress is low, but I would still do all the regular stuff. If you have to change a failed cam, that's really unpleasant...especially on a flathead. Crane goo on the lobes, Crane or GM EOS mystery fluid in the oil. I still follow the ancient Honest Charley catalog breakin advice of running the oil a quart high--seems to make sense for cam break in, as cam is mostly lubed by splash. And on a flathead, cam journals and bearings must be good--that's a point of major loss of oil pressure if worn out.
Thanks Bruce. I don't know if the cam has break in lube or not on it. It was installed by the machine shop so I am assuming it does. I've heard good things about the GM EOS, so I'll recommend that. What oil should we run? Machine shop said straight 30wt. Is that correct?
Straight 30 is what I would use, just from tradition. Flatheads can't easily/quickly be primed once assembled without a pressurized tank. What I do is to hook a piece of suitable tubing to a can and let about two quarts of oil run into the engine through the pressure sender hole in the back. When I've done this close to startup time, I've gotten pressure on the gauge as soon as starter engaged, and full pressure immediately on fireup.
[ QUOTE ] What I do is to hook a piece of suitable tubing to a can and let about two quarts of oil run into the engine through the pressure sender hole in the back. [/ QUOTE ] Bruce, brings back some old memories! The first flathead I built (well stood by and watched) the old "dog" that built the engine had me stand at the back of the engine with an old style pump oil can, and keep squirting oil (fresh, #30 if I remember) down the oil pressure sending unit hole until I had pumped in 5 quarts! Thinking back, I think he did this as a good way to keep me busy! (and give me a sense of "I helped build this engine!" ) As I remember it took about 6 hours! (real small oil can! )
Confession: That's how I actually do it. I suggested the can because it sounded like a better way for a rational human being--I actually enjoy standing there squirting away til my hand hurts and watching the oil trickle down the galleries as the paint dries on the bellhousing. I must be retarded or something...gotta go watch the clothes dryer do its job, bye.
One last thing here... the machinist recommended pulling the spark plugs and spinning the motor with the starter to prime the oiling system. What's your take on that? That sounded much more risky than the previously mentioned priming system.
I say primeit and startit with no fooling around. I think slow cranking with unbroken-in cam is a bad idea, personally. Top up the carb (single stock Holley for breakin, regardless of future plans!) with gas (squirt can through vent), fill bowl of fuel pump, double check all ignition settings and firing order, and letterrip. Then go get the distributor rotor you left on the bench...
Bruce, a lot of the old timers say, "fire it up and bring the revs up to about 1500 - 2000 RPM; keep an eye on the oil pressure, and if all is well, keep the engine running at a fast idle for about 20 min. That gets the cam settled in." This maxum still hold true?
I second Digger Daves way of doing it. I have always done all new engines this way, regardless of what it is. Never have a ny problems in the last 30yrs .
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