Does anybody know how many RPM's a flatty can safely take? Stock peak hp is 3400 to 3600. I just rebuilt my 52 8rt flathead , bottom end stock, but I put in a 3/4 race cam and tri-power with offy heads. I used these parts cause I had them from the 50's, all brand new. I didn't build this to race, ---- BUT---- I know I am going to want to step on it once it is broken in. Anybody know what a 3 main bearing engine flatty's rpm limit is?
thanks Chris

 

Every engine is different, but the correct answer is one rpm less than when the bottom falls out.

But seriously, folks, they are very heavy bottom ends and I don't think I would be comfortable turning one much more than the rated peak hp speed without doing a bunch of work down there.

 

The heavy crank is a plus, as long as it's balanced. Same for the clutch and flywheel.

As long as you have the proper clearances, good parts, and plenty of oil pressure, you can run it all day at 4,000 RPM (the stock car racers used to). The stock rods are very strong, and you're not likely to float the valves if you followed the cam mfr's recommendations.

Unless you've ported the block pretty extensively, spent some money on the ignition, and got the tri-carb setup perfectly dialed in, there's precious little reason to go much above that. Roll the dice, baby!!