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Engine's RPM range prop size 1972 70hp

M

mac_55

New member
1972 70hp Chrysler
1962 14' Comet

anyone have an idea what the engine's RPM range is so i can pick the right prop and get the most out of my engine? right now i run a 13x16 but am getting a 13x21 on saterday..

Thanks
 
Re: Engine's RPM range prop size

i had a 13x16 and its over 7000rpm so i got a 13x21 and im still way over 7000rpm im thinkin bad tach or ......?

did a tune up on the engine in the spring and runs better then ever
 
Re: Engine's RPM range prop size

yep i picked up a newer tach and sure enough that is the problem so now i have 13x21 prop with a 91 force trim and tilt

im excited to test it tomorrow ,,also swapin a set of carbs on from a 85hp , that should go a little faster
 
Re: Engine's RPM range prop size

Don't throw out the old carbs - you might find you have a severe flooding problem with the carbs off the 85 horse unless you also plan on modifying the intake and even then you could end up with an exhaust system that can't handle the extra volume...
 
Re: Engine's RPM range prop size

from the two chryslers i have the 70hp and the 85 hp all the numbers on the blocks heads pistons everything they all seam to be the same engine except when it comes to the carbs they have different numbers stamped and different jet sizes
 
Re: Engine's RPM range prop size

It's almost never "just the carbs" - I would check out the reeds as well - something else is bound to be different...
 
Re: Engine's RPM range prop size

Changing to a bigger carb ain't gonna do anything but waste gas.That motor is set to run optimum with what it has on it now.
Post a pic of your carbs and the #s.I know someone that needs a set.J
 
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