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Or Seth, either one
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Discussion Starter #1 (Edited)
Flat v-drive, 396 BBC, iron heads and block, +/- 10.5:1 CR, max rpm +/-5000, Neovane A-755 (I think) cam driven water pump

Idles and cruises at 120*, gets up to about 160* running it hard. The reason I'm considering a thermostat is once it's up around 160* it doesn't want to idle all that well. I've also read that power and efficiency suffer if the engine is kept too cool. Thinking it might not be a bad idea to add one of those kits Rex sells.

One of my concerns is; will allowing the engine to run warmer possibly cause detonation issues, running 10.5ish :1? (premium pump gas of coarse)

Any thoughts? Pros, Cons?

Thanks guys!
 

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Flat v-drive, 396 BBC, iron heads and block, +/- 10.5:1 CR, max rpm +/-5000, Neovane A-755 (I think) cam driven water pump

Idles and cruises at 120*, gets up to about 160* running it hard. The reason I'm considering a thermostat is once it's up around 160* it doesn't want to idle all that well. I've also read that power and efficiency suffer if the engine is kept too cool. Thinking it might not be a bad idea to add one of those kits Rex sells.

One of my concerns is; will allowing the engine to run warmer possibly cause detonation issues, running 10.5ish :1? (premium pump gas of coarse)

Any thoughts? Pros, Cons?

Thanks guys!
i have a 489 12.1 roller,with alumunum heads run a 180 theromstat, on 91oct never a big deal.
 

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Or Seth, either one
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Discussion Starter #3
i have a 489 12.1 roller,with alumunum heads run a 180 theromstat, on 91oct never a big deal.
The thermostat kit that Rex sells comes with a 160*. They claim water temp will fluctuate between 160 and 190. What does yours max at with the 180* in there?
 

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Boat Nut
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We put one on a jet boat, last season, had issues with the exhaust hose burning, and the headers getting hot. The headers were Lightning's, the t-stat by-pass, did not pass enough water to cool the hoses at idle. We ended up teeing into the supply line, one line feeds the header's, the other feeds the engine. Now the discharge from the t-stat, get discharged overboard. This set-up was tested last fall, seemed to be fine with a 160 degree hi-flow T-stat. Has worked fine all this season with no issues, stays right at 160.
 

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Just another Wannabe
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I have always been told that for a gasoline engine you want the water as cold as you can get it. (I really don't know, I really only run alcohol.) That is why NHRA pro stock guys either have a water chiller in their pits, or feed ice cubes into the radiator between rounds. They want to stage the car with water temp as cold as they can possibly get it. In fact a crew chief told me that one run they made in testing was a total loss because the water temp was 110 when he let out the clutch. And that was unacceptable. as he said; "We should have caught that and towed it back to the pits."
Those guys would love to have an endless supply of 60 degree water.
 

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OOOPS yeh untill I put in an oil temp gauge I'd never have thought my water could be 120* and my oil 220*.
 

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Just another Wannabe
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Actually that is quite common. My little boat I just built runs wide open and the oil temp stays about 120 to 140 degrees hotter than the outgoing water.
 

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Or Seth, either one
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Discussion Starter #13
Guys, I don't have a race boat. I just want to be able to go out for the day and have a great running boat. If 120 is where I want to be, then how do I adjust things so that it wont go too much higher? I really don't care what NASCAR or even "Grave Digger" runs. This is not a max output situation. What will make the engine reliable and trust worthy?

Am I asking the wrong guys??? :)sphss
 

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If you had an oil temp gauge you'd see how little water temp had to do with the price of tea in china. btw I have a rex 4 port therm housing sitting on my shelf It's yours if you want to pay the shipping.
 

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Or Seth, either one
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Discussion Starter #15
I prefer 120-140... in that range anyway.

Worry more about oil temp more than water temp in our boats.
Our boats, Your Boats?
Our boats, Race Boats?
Our boats, V 8's?
Our boats, ???

Your boats are WAY beyond my current scope... Is this advice really for me???
 

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Guys, I don't have a race boat. I just want to be able to go out for the day and have a great running boat. If 120 is where I want to be, then how do I adjust things so that it wont go too much higher? I really don't care what NASCAR or even "Grave Digger" runs. This is not a max output situation. What will make the engine reliable and trust worthy?

Am I asking the wrong guys??? :)sphss

All stock merc motors run thermostats. If you run a 140, your motor should run around 160 or so. Remember, it STARTS to open at 140 and will be fully open by 160. I run them on my blower motors and they always stay between 150 and 160 depending on winter/summer water temps. In the long run, i think it will help engine longevity.


Darrell.
 

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Is a v-drive and a jet themostat the same I know they make 3 port and 4 port ?? mines a 4... I don't want to blow budwiser's chit up. Can't find the frickin spring either. I'm thinkin a v-drive therm set up is prolly different than mine???????????
 

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I have everything but the spring, brass t's, and thermostat. I'll keep looking I should post a pic of my garage , you'd all say holy $hit clean that place.lol
 

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No Race Boat Here

I run this Rex Kit on my Hydro and Flat, LS6 Chevy Iron Heads pump gas no problems. I have used the same kit on my jet boat for 10 years no problem, however I just installed and new 540 Dart Block Iron Head in the jet and added a Rex bypass pressure valve on the inlet to block. I was pegging a 60 pound guage on the discharge of jet pump. Now I wonder what kind of pressure a cam driven water pump pushes and 7000rpm?
 
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