New Owner with questions

[cfelton]

I would definately change to a 4" heat exchanger if possible. After I rebuilt my 170 it ran a little warm, about 170-180 while up on plane. I bored it .040 over, so the cylinder walls are a little thinner and it has a little more compression which will cause it ta run a little warmer. I replaced the entire water pump and it cooled down a little. After I got it broke in I changed the oil with 40wt. motor oil and added a quart of LUCUS OIL STABILIZER and my oil pressure rose 20 psi and it really cooled on down. Now it rarely gets above 165 degrees. The engine temp depends on the raw water temperature also! Try the Lucus oil stabilizer, its really great stuff!