Have newly rebuilt 454 with 177 Blowers. Had high flow brass thermostats when I got the boat. Stats say V142 and 4H7 on the bottom. Should I stick with this style stat and keep water temp at 140? Engines have crossovers.

couple pics of the old ones....

Keep water temp at 140F. Sea water has salts, other than table salt, that precipitate at higher temps causing scale in the water passages of the block and heads. See you are in CT so the sea water part applies to you right?

Well, the boat will be on a lift on the Ct river about 40 miles from the ocean, so its fresh water. But, we do go in the ocean alot. So, alittle of both, salt/fresh.

The 525SC's that are very similar to your engines use a 140* tstat. I would keep the 140* unless you are having problems.

Ok, will do!