BUP, you are, and I appreciate it like most others do.

No bet, lol.

I know a lot of the later model carb app's used 160 t stats. If I'm replacing one in someone elses motor I will go with what is called for. If someone puts in a 140, I will not worry about it.If it has any mods at all, I will usually recommend the 140F.

That said, personally, I have no issues with a 140F t-stat in a carbed application.

EFI, I will jump up and down with you. In fact, I may help you jump higher. LOL.

I hear you but for ME I have to follow OEM rec and specs - one is for warranty purposes and 2 for liability purposes plus class training we always brought up that temps are very important even for carb apps. Just saying. You know I have to bust on you a bit with the smack

It possibly came from the factory with a 140 t stat, which would make perfect sense of his gauge readings. But someone later on might have stopped at his local autozone & replaced it with the closest car stat they could get...the 160. My 1988 454 mag came with a 140. I'm running a crossover now & rarely see anything over 115-120. Happy boating!!

Thanks for the feedback and info guys.

I guess I better get my engine serial number to settle this debate eh? I wish we could accept bets...

I'm guessing from the other digging I've done, that this actually will be the 143 Tstat. The engine is referenced as the "454 magnum bravo" in other documentation I've read. The plate on the carb says 4600-5000 rpm range... if that helps.

Is the serial number you're referring to the same thing as the "casting number" that I would find somewhere on the block, or is that serial number on this carb hat plate as well?

Carb hat plate.

Get the 140F. :Smile:

I've got another can of worms to open...

So, lets say we discover the the OEM tstat IS 140/143. Even so, wouldn't the engine operate better and more efficient at 160?

Take into account these facts:
* it is a raw water cooling system, but It's never been in saltwater, and never will be
* It'll mostly always been in freshwater lakes in the northwest, purely fed by mountain and spring water
* "Warm" water around here is 70*. Parts of these lakes never get above 60.