Thermostat or restrictor plate?

Automotive powered airboat discussion.
jeepinocala1111
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Thermostat or restrictor plate?

Postby jeepinocala1111 » Thu Jul 28, 2016 6:53 am

What is the best most reliable let's just say I want to do this once. Like a lot of people it has been 15 years since I messed with car engines as for performance and have never owned a car engine airboat so this is the new start for me but I watched my temps go from 180 to 200 back and forth and when at 200 it would all of a sudden go down to 180 pretty fast my though is sticking thermostat. My second thought is why the hell run one in this engine? I always ran restrictor plates in my race cars. HELP :dontknow:

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Re: Thermostat or restrictor plate?

Postby CactusJack » Thu Jul 28, 2016 8:39 am

I would run a quality thermostat myself.... yes, many people have never used a thermostat.... don't need one, always chuck it in the trash first thing....

However, a thermostat (good quality) will get your motor UP to temp quicker, then keep the coolant temp more constant. The thermostat also makes the coolant in the motor circulate and pick up more heat then stay in the radiator longer to get rid of more heat..... so, imo, a thermostat is very necessary... after all, car manufacturers wouldn't have spent $ designing the motor with a thermostat if it didn't need one. Motors are designed to run at a particular temp.... running the engine cooler for longer with no thermostat will only cause the motor to wear.... so a quality thermostat will get it up to temp much, much faster.

Race cars often get away with just a restrictor plate in place of the thermostat because the motor is going to be going flat out most of the time and isnt expected to last anyway..... when you compare how many miles/hours a race car engine runs in a season and gets rebuilt every few race meetings anyway..... longevity isn't considered.

If you want your airboat motor to last many years without rebuilding it.... I would definitely get a good quality, early opening thermostat that has a little ball thingy to let air thru (or one 3/16 hole drilled in the skirt).... run good head gaskets and coolant....... and forget it for about 5 years :wink: I keep saying 'Quality' thermostat, because the cheap ching chong junk will more than likely cost you your engine.... when you least expect it :cry: If you have to, get a thermostat from your engine make's dealership.... not from a crappy ching chong parts distributor.... they are cheap for a reason.....

Just my opinion.... now.... where is my flame proof suit..... Ahhhh here it is :lol:
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Deano
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Re: Thermostat or restrictor plate?

Postby Deano » Thu Jul 28, 2016 9:27 am

If you've said, I didn't see it, but what engine are you running that we are talking about?

The way you describe the temperature acting, it sounds like there is still air in the system and it needs a better burping. With that being said . . .

My preference is to run a 160* which generally has me running a little warmer than that. Sometimes a Caddy can be reluctant to come up to temp without one and they run better warmer. Most late model engines are designed to run at, and are more efficient running at a higher temperature. But the reality in any case, is that the warmer you run, the less time there is recover when something takes a dump. Obviously, after you are familiar with how it acts and determine how to best size it, it is quite possible to run a restrictor in lieu of a thermostat. Consequently, running one or not is a personal preference dependent on how warm it runs, how it is typically loaded, how you use it, etc.

You didn't mention if the gauge was mechanical or electrical. With a new (to me) engine I would use a heat gun to determine and/or confirm where it was really running heat wise before did to much different. It may be possible that the sending unit needs replaced, which could also yield the screwy gauge results. Mechanical can have capillary tube issues as well. Here again, I would start with a heat gun and independent confirmation of what I was really dealing with before I changed to much.
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blow boat
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Re: Thermostat or restrictor plate?

Postby blow boat » Thu Jul 28, 2016 10:37 am

I cut out stat with a pair of dikes remove
Stat and just run the base of stat which
Is just a restrictive not running anything
Coolant moves to fast and does not remove
Heat as well it sounds like you may have
Air pockets or low coolant level....?!

Now if you have efi motor and not carb disregard above post :P

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Re: Thermostat or restrictor plate?

Postby scottyroll » Thu Jul 28, 2016 10:52 am

jeepinocala1111 wrote:...but I watched my temps go from 180 to 200 back and forth and when at 200 it would all of a sudden go down to 180 pretty fast my though is sticking thermostat.


I think that is a clear sign that your thermo is working properly.

The opening and closing allows the radiator to do it's job by cooling down the hot water rather than just circulate hot water all the time.

People will swear both ways whether to run one or not but the fact is that GM include them for a reason and that's why I run one.
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John C
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Re: Thermostat or restrictor plate?

Postby John C » Thu Jul 28, 2016 11:51 am

I always ran a 1" or 7/8" restrictor plate. Never had any problems. Temp would not fluctuate, it was always consistent. but that's down here in Florida. Probably run a T-stat if you have to contend with cold weather.

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Re: Thermostat or restrictor plate?

Postby SthrnStyle3 » Thu Jul 28, 2016 1:16 pm

I have a sbc with a gearbox and I was running a gutted out thermostat. It did fine, but when it got colder during hunting season, it would take forever for my motor to warm up. I was usually already to my spot before the motor had a chance to get warmed up. I am currently running a 160 thermostat. It helps to warm it up faster on cold early mornings and when it's hot out, it stays open anyway acting like a restrictor plate. With this heat we are having though it's hard for anything to stay cool. It's not uncommon for my motor to run around 195 cruising and spike around 200 if ran a little hard, during these summer months.
12' aluminum hull, 350 sbc w/ flattop Pistons and camel hump heads, side by side seating w/ double in front, 2:1 gearbox and a 78" whirlwind whispertip 2.0

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Re: Thermostat or restrictor plate?

Postby jeepinocala1111 » Thu Jul 28, 2016 1:28 pm

Deano wrote:If you've said, I didn't see it, but what engine are you running that we are talking about?

The way you describe the temperature acting, it sounds like there is still air in the system and it needs a better burping. With that being said . . .

My preference is to run a 160* which generally has me running a little warmer than that. Sometimes a Caddy can be reluctant to come up to temp without one and they run better warmer. Most late model engines are designed to run at, and are more efficient running at a higher temperature. But the reality in any case, is that the warmer you run, the less time there is recover when something takes a dump. Obviously, after you are familiar with how it acts and determine how to best size it, it is quite possible to run a restrictor in lieu of a thermostat. Consequently, running one or not is a personal preference dependent on how warm it runs, how it is typically loaded, how you use it, etc.

You didn't mention if the gauge was mechanical or electrical. With a new (to me) engine I would use a heat gun to determine and/or confirm where it was really running heat wise before did to much different. It may be possible that the sending unit needs replaced, which could also yield the screwy gauge results. Mechanical can have capillary tube issues as well. Here again, I would start with a heat gun and independent confirmation of what I was really dealing with before I changed to much.


I believe you are correct on this I always use either a thermostat with a bypass hole or a water pump with a bypass and mine has neither so when filling up there is airpockets to rid. I am going to get a bypass thermostat to rid the issue. The boat was rebuilt so it was just refilled explaining the air pocket. Thank you for the help.

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Re: Thermostat or restrictor plate?

Postby blow boat » Thu Jul 28, 2016 1:44 pm

jeepinocala1111 wrote:
Deano wrote:If you've said, I didn't see it, but what engine are you running that we are talking about?

The way you describe the temperature acting, it sounds like there is still air in the system and it needs a better burping. With that being said . . .

My preference is to run a 160* which generally has me running a little warmer than that. Sometimes a Caddy can be reluctant to come up to temp without one and they run better warmer. Most late model engines are designed to run at, and are more efficient running at a higher temperature. But the reality in any case, is that the warmer you run, the less time there is recover when something takes a dump. Obviously, after you are familiar with how it acts and determine how to best size it, it is quite possible to run a restrictor in lieu of a thermostat. Consequently, running one or not is a personal preference dependent on how warm it runs, how it is typically loaded, how you use it, etc.

You didn't mention if the gauge was mechanical or electrical. With a new (to me) engine I would use a heat gun to determine and/or confirm where it was really running heat wise before did to much different. It may be possible that the sending unit needs replaced, which could also yield the screwy gauge results. Mechanical can have capillary tube issues as well. Here again, I would start with a heat gun and independent confirmation of what I was really dealing with before I changed to much.


I believe you are correct on this I always use either a thermostat with a bypass hole or a water pump with a bypass and mine has neither so when filling up there is airpockets to rid. I am going to get a bypass thermostat to rid the issue. The boat was rebuilt so it was just refilled explaining the air pocket. Thank you for the help.


Yeah, just burp it after you run it when it's
Cooled down and top it off may take a
Few times, but a 20 degree swing is
Not normal and will make hot spots

Best of luck..!!

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Re: Thermostat or restrictor plate?

Postby terrible ted » Thu Jul 28, 2016 5:45 pm

If it a burping problem on my 350 i drilled and taped a small hose fitting right into the top of the t sate housing and piped it up to the fill can.

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Re: Thermostat or restrictor plate?

Postby jeepinocala1111 » Thu Jul 28, 2016 5:47 pm

I think I am going to go with one of these Stewart High Performance Thermostats 301 because it will do away with chances of air pockets when filling, flushing, and I believe my boat does not have a bypass.

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Re: Thermostat or restrictor plate?

Postby terrible ted » Thu Jul 28, 2016 9:15 pm

thermostat or no thermostat wont really effect air pockets. The air pocket created by air trapped at the top of the motor.
My thermoset housing hose went to the rad below the motor. The air moves up and doesn't flow out. with out a way to burp the system it always returns. If that's the problem.

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Re: Thermostat or restrictor plate?

Postby jeepinocala1111 » Thu Jul 28, 2016 10:00 pm

terrible ted wrote:thermostat or no thermostat wont really effect air pockets. The air pocket created by air trapped at the top of the motor.
My thermoset housing hose went to the rad below the motor. The air moves up and doesn't flow out. with out a way to burp the system it always returns. If that's the problem.


The radiator is below the engine what is going on I believe since it has a thermostat it has one with no bypass holes and since the water pump has no bypass on it the air would take a bit to get out of the engine but with the one I am buying it has small bypass holes so it will not trap air under the thermostat. I can burp it but want to be able to flush it out once in a while without having to go through this.

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Re: Thermostat or restrictor plate?

Postby crazycoonass » Thu Jul 28, 2016 10:58 pm

Definitely sounds like air in system. If everything is working right with no air in system your temperature will swing five or so degrees under normal conditions. Of course if you are running harder your temp will most likely go up. But it won't swing twenty degrees suddenly. I had trouble with air until I moved my radiator above the engine. Burped air out one time and no trouble since. I run a 160 degree thermostat in my engine. Also having the correct pulley size is important. If you under drive the water pump slightly you'll get good water flow at lower rpm's. And I firmly believe GM engineers put thermostats in engines for a reason. So why remove it?

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Re: Thermostat or restrictor plate?

Postby terrible ted » Fri Jul 29, 2016 7:08 am

I know I seen t housing for small blocks that have a neck that have a cap at the top. I think all my t stats had weep holes. I even has issues with restrictor plates.

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Re: Thermostat or restrictor plate?

Postby jeepinocala1111 » Fri Jul 29, 2016 11:08 am

terrible ted wrote:I know I seen t housing for small blocks that have a neck that have a cap at the top. I think all my t stats had weep holes. I even has issues with restrictor plates.


Mine has the t housing with the cap at the top what was going on is it may be higher but that still will not bleed the air from under the thermostat.

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Re: Thermostat or restrictor plate?

Postby John Fenner » Fri Jul 29, 2016 11:20 am

My MGB with a 350 sbc has a thermostat but I ran a 1" reducer plate with a smaller radiator before I restored it, now with a bigger radiator the heat climbs at highway speed, will be making another reducer plate to cure this. I guess it is all in tuning your rig, whatever it might be.
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