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i'm approaching the end of my break-in period, and i've managed to be very responsible. i haven't wound the cleveland any higher than 4k rpm (and then only briefly as i approach a shift) and have varied my driving greatly. when i complete the break-in, how high can i safely spin this thing? i'm not talking about sustained rpm's, i'm just talking about winding it up and then shifting. the sound of the motor at 4k sounds like it's screaming...i can't imagine what 6k sound like. the motor is a 4v with closed chamber heads, stock valves, comp cams 270h with matching springs/timing set/lifters, stock rods/bolts/crank, clevite bearings, kb hypereutectic pistons, and no oiling mods other than hv oil pump.
 

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My c starts chewing on pushrods at 6k, but it's a 2v Hydro cam. A 4v solid lifter should be able to spin as high as 7k, but boy will it be screaming.
 

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If no oiling system mods were made I would not go past 6000 RPM. A poor oiling system was the big draw back to the Clevelands.
 

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i hate to sound like a complete and utter Newbie (even though i am) but what do you mean when you say the "valves float". I have heard it before but I do not understand what it is.

Thanks for any info, oh and i havn't taken my Clevland over 6K because I am parinoid, but my uncle who built the motor said it is safe.
 

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valve float refers to when your engine RPM is so fast that the springs on the head can't physically close fast enough before the spark comes to the cynlider and the piston is all the way up. When this happens if the motor is not built with very tight clearances the valves can contact the piston causing an alomst instantanous melt down in the motor resulting in lots and lots of damage. If the clearances aren't too tight, nothign much happens aside the power drops off and you can get flames both out your carb and down the exhaust because the valves didn't close.
 

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alright thanks for the info. Learn something new every day.
 

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I hope that you didn't keep the 4 groove valves. Even the boss and HO had single groove keepers. I've had my 351C 4v over 7000 a few times and not on purpose and haven't hurt it. With 4 grooves I'd limit it to 6000 or maybe less.
 
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