Ok Flathead guys, So I wanna build a flathead for my 34. I wanted to run a 4" merc crankshaft but a 3 3/4 balanced and ready to go crankshaft just fell into my hands yesterday for free. The cars gonna be a driver, should I use the one I got or get the stroker?
Just my unfounded opinion. Flatheads compared to todays cars are mostly so slow it makes no difference. Yes I know Ron Main and Jimmy Stevens have 300 mph flatheads. But the average street driven flatmotor is getting blown off at every stop light by old ladys in 1600cc vans. So if it was me I would use the stock crank and save the 4 inch crank for a racer.
The balancing means nothing unless you have the whole rotating assembly that the crank was spun up with. Pistons, rods, rings, bearings etc. NOW this is important, if you have the balance card or the actual bob-weight, and by some chance your componants are very close to the same, you can then use the crank balanced as is. Some here will run it and think nothing of it. Theres a big diffrence in weight from say a .125" over cast piston with 4 rings to a .030" over 3 ring forged piston. Yes enough to make a diffrence you need to think about and consider. Ive been doing this all of my life, I hope that helps you with your decision. Please keep in mind, I'm very anal when it comes to engine builds, again others might very well say run it and dont think twice. TR
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