What thermostat should I run?
 

I have a gen VI 425 ho crate motor in my boat. I am trying to mimic the gen V 454 mag carb from mercruiser. When I look online in the parts catalogs, it shows a 160 degree thermostat. But I think I saw other gen V 454 mags with 140 degree thermostat? So I'm not sure what one to run. I installed a 160 and when I ran it, I believe the temp got up to around 170 or so. Is this ok? I don't want condensation in my oil or valve covers. Like I said I have the 454 crate motor with aluminum dual plan intake, stock heads and valve train. holley 750, gil exhaust with dry tails, circulation pump. [ATTACH=CONFIG]516268[/ATTACH]

Carbed Merc engines run a 140* Tstat and that is what I would use.

x2

140* also

For instance, on mercruiserparts.com for a 454 mag with carb it shows both a 140 and a 160 with two different thermostat housings. I have the thermostat housing that shows the 160.

http://www.mercruiserparts.com/selec..._nbr=821723+92

id go with 140

Oil temp is what you need to look at to keep the condensation down .
We run the 632s at 130 on the water and 230 on the oil

x2

I run a 160 but I boat in real cold water, sometimes only 34 degrees. When I run real hard my oil hits 270 but for the most part the oil sits around of 200.

Yep we don't run hard till 180 on the oil and at 260 watch it and at 280 abort.

Smart way to manage your oil temps. An oil thermostats system is pricey and it is only used for small % of the boating time.