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I have a 1967 wayne 48 pass. with a chevy 350 4 speed tran. with a split rear end. at 3400 rpm's i am going about 55 mph. is this too high of rpm's to run a long distance down the interstate? what is the most rpm's i could run with out hurting the engine? i have a 160 deg thermostat but i can't get it to run under 190deg. any ideas thanks
You do not want to exceed a piston speed of 2100 ft/min for extended periods of time. The correct formula for calculating piston speed is rpmxstroke divided by 6. So in your case 3400 x 3.48 divided by 6 equals 1972 ft/min. As you can see this is below the magic number of 2100 and therefor you are judged to be in the "safe" area.
Befor we get into a long and convoluted discussion on piston speed theory please remember that this is for a "street engine".
The reason for the 2100 ft/min barrier is because at piston speed greater than this there is a condition set up in the engine called "harmonics".
These harmonics can cause undue piston ring vibration leading to the destruction of the ring lands brtween the pistons. This leads to the desintigration of the piston etc, etc, etc.. Enough said. Happy busing!!
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