33mph at 3200rpm? even possible?

[xjdriver]

So i took my 1964 16' starcraft sea mist out last weekend with a new faira tach that i installed its set on 6. At wot it ran 33mph gps speed while the tach said 3200rpm is it even possible to be that overpropped? Or is my tach wrong? Engine is a 1975 70hp rude with a 13 3/4 x 15 stainless prop. The tach does jump around at low rpms, but seems steady at higher rpms, im not sure what could be cousing that either. Thanks for looking.

 

[V153]

Re: 33mph at 3200rpm? even possible?

Your tach is probly wrong or you're way over-propped. A 13 3/4 is purty honkin for a 70 btw. Are you sure yer actually gettin wot?

~30 mph @ ~3000 rpm is kinda a magic #. Great place to cruise for any gas driven boat. Provided yer tach is accurate.

 

[xjdriver]

Re: 33mph at 3200rpm? even possible?

Ya, its getting wot, at the time anyway, now the timing advance is sticking i guess i need to lube the timer base somehow