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Unread 05-29-2008, 09:05 AM   #1
diamatron
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1978 CJ7 
 
Join Date: Dec 2001
Location: ohio
Posts: 102
Thermostat Temp.

I have crawed a few threads and found mixed results on the recommended thermosat in my 304. I have a leak at the housing and am going to replace the thermostat while I am in there. Right now I am runnning a 180. My heat inside is just okay, not great.

My opinions:

To stay at 180... BEcuase I am experiencing aome fuel boil problems in my edelbrock carb after shutdown. I installed a new HEI, and now its pretty easy to start anyways, but the fuel bowls will boil over flooding my engine on hot days. Not while the engine is running, it happens after I shutdown, making the next startup flooded. Also, I do tend to burn off some oil somehow. I am not sure where my oil goes exactly, but A hotter engine may birn off more. I havent any leaks on my garage floor, so I assume is goingat a out through my piston alittle.

To goto stock 195... I am running a fan clutch, and it probably is looking for the 195 to make the radiator work properly. And, I do believe and hot engine is a efficient engine.

I was wanting to here some other opinions on my setup. My last upgrade was Edelbrock headers, and they have given me some more HP!!! Low end is much improved!! I realize they run hotter in the engine bay, but they also cool off faster, so far I have not noticed fuel boil issues anymore. Though it's only been in th e 70's so far this year too.

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Unread 05-29-2008, 10:19 AM   #2
jfwireless
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I run a 160 degree thermostat in my 304 down here in South Florida. I added dual exhaust 2.5 inch exhaust to the back of my Dynaflow headers. I have an edelbrock performer intake feeding a TBI throttle body. I moved over to a junkyard TBI setup to get rid of all those carburetor issues and hard starts. No more fuel bowl in the carburetor to deal with. The high pressure fuel system constantly flows fuel through the system back to the fuel tank keeping the fuel cooler. The 304 has more power, faster starts no matter how long she sat, better gas mileage and smoother running all together.

It did take me some time to figure all this TBI stuff out, but now I am very happy with it.

Jim

Jim
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Unread 05-29-2008, 12:07 PM   #3
SuB8HaVeN
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I always run whatever is stock (195 in this case). A hot motor is not good, but if you're running the stock spec thermostat and you're overheating you have other issues you need to take care of. A motor running cooler than it is supposed to will also cause it to not burn the fuel as efficiently as possible. They're made to run at a certain temperature for a reason. If they needed to run cooler they would already come with a lower thermostat.
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Unread 05-29-2008, 12:50 PM   #4
Mike Romain
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You should run the 195. The thermostat only controls how 'cold' the engine runs, not how hot. The fuel vaporizes better when warmed up also.

Stock, Jeeps have a serious vapor lock issue so they started making them with a fuel return line and a dual outlet inline filter. This filter has a center line going to the carb and a top metered one going to the return line. It is up top so the air that boils in on a hot shutdown rises up and gets blown back to the tank instead of emptying out the supply line to let off pressure. The return also has to be up top or gas will siphon back to the tank when it sits causing vaporlock no matter how cold or hot it is.
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Unread 05-29-2008, 05:11 PM   #5
jfwireless
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[QUOTE=Mike Romain;5275044]You should run the 195. The thermostat only controls how 'cold' the engine runs, not how hot. The fuel vaporizes better when warmed up also.

Mike, the thermostat does raise the temp of an engine to the operating temperature designed for the thermostat. For examples my 160 degree thermostat puts me in the 170 -190 degree range, a 195 would most likely put you in the 190 -220 temp range. So a 195 thermostat runs a engine hotter than a 160 degree thermostat. Obviously, if you don't have the capacity to cool an engine than no thermostat will keep an engine running as cool as possible.

Manufacturers raised the operating temperature of engines in the 79's to meet environmental emissions parameters, in my opinion to the detriment of some engines. When I removed all that pollution control stuff and went to a TBI controlled engine, I lowered the engine temp with a 160 degree thermostat and it runs better and cooler. Nothing harder on an engine than heat.

As far as fuel temperature, the cooler the better, the cooler the fuel and air the more power you will receive from the combustion process as the air and fuel will be denser per unit volume giving you more power.

Jim
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Unread 05-30-2008, 09:49 AM   #6
Mike Romain
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[QUOTE=jfwireless;5276247]
Quote:
Originally Posted by Mike Romain View Post
You should run the 195. The thermostat only controls how 'cold' the engine runs, not how hot. The fuel vaporizes better when warmed up also.

Mike, the thermostat does raise the temp of an engine to the operating temperature designed for the thermostat. For examples my 160 degree thermostat puts me in the 170 -190 degree range, a 195 would most likely put you in the 190 -220 temp range.
You must have a well behaved cooling system, most of the 258's I have seen up here in Canada run right at the edge for cooling to the point the heater fan is sometimes needed to cool them down. Same for the Cherokee, ours only had the one fan on it and in 4 low on a hot day, it just plain wasn't enough to the point of the engine light coming on. 'With' a new radiator and a new fan clutch also. If we had of kept it, (it rotted away) I was going to put a second fan in it.

My engine also runs like a pig when cold, it likes to be warmed up seeing as the fuel/air mix is set for a warmed up engine.

I don't have a lot of experience with the V8's. Do you run a 3 core rad?
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 05-30-2008, 02:01 PM   #7
jfwireless
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Mike:

Yes, I run a 3 core radiator. But I live in South Florida and its hot all the time. The temp swing here is less than 50 degrees from august (100) to January (50), so I have used a 160 degree thermostat to get ahead of the heat. In Canada, you most likely have something like a 100 degree temp swing at least, so I would think you would use a higher degree thermostat. When its August and you are stuck in a traffic jam things start to break down, but somehow this little rig seems to stay fairly cool, never goes over 200 on a really hot day. I have not installed an electric fan yet, I am still running the stock original 7 blade fan without any clutch. It works so well I have not had the courage to change it out to an electric, although I have one ready to go.

Jim
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Unread 05-30-2008, 02:33 PM   #8
Mike Romain
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Quote:
Originally Posted by jfwireless View Post
Mike:

Yes, I run a 3 core radiator. But I live in South Florida and its hot all the time. The temp swing here is less than 50 degrees from august (100) to January (50), so I have used a 160 degree thermostat to get ahead of the heat. In Canada, you most likely have something like a 100 degree temp swing at least, so I would think you would use a higher degree thermostat. When its August and you are stuck in a traffic jam things start to break down, but somehow this little rig seems to stay fairly cool, never goes over 200 on a really hot day. I have not installed an electric fan yet, I am still running the stock original 7 blade fan without any clutch. It works so well I have not had the courage to change it out to an electric, although I have one ready to go.

Jim
I run a fixed four blade fan on a 2 core. When I got it recored from the stock one, they put in 25% more cores which made my temp gauge actually drop the same 25%.

I do see more like 150+F degree swings in my CJ7. Have been out in -40 and 110-120F. It is my daily driver for over 10 years now. I also have to keep the minimal of emissions on it for the sniffer.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 05-30-2008, 06:45 PM   #9
OldSailor
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I run a 180-deg thermostat, 4-blade steel fan with fan clutch, and 3-row radiator on my slightly-warmed-up AMC360. I replaced the radiator about 10 years ago. I flush the cooling system every 2 or 3 years. Engine coolant temp runs 205 in the winter and 220 in the hot summer. Never overheaats.

I tried a 160-deg thermostat in the winter to get the thermostat to open up sooner. Didn't like that -- engine bogged a little on hard acceleration until warmed up because the quickly opening thermostat didn't let the engine warm up quick enough. I also tried a 195-deg thermostat, but that took too long on cold winter days for the cab heat to work good. Didn't want to change thernmostat's twice a year, so I stuck with the 180-deg 'stat and I've been happy with it.

Mike's right - the thermostat only controls engine temp until the engine temp is at the temp setting of the thermostat. Once the thermostat is fully open, it doesn't have any more control on engine temp (unless it's clogged or otherwise damaged). Some people think that installing a 160-deg thermostat is going to keep their engine coolant temp down at 160 all the time. Not so. In fact, if the engine ran at a constant 160 degrees, fuel utilization would be crappy, even on an older V8 like mine.
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Unread 05-30-2008, 07:40 PM   #10
SuB8HaVeN
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I run the stock 195 with a 3 core radiator and electric fans, and I can sit and idle all day long on the trail (have done so many times) and it won't skip a beat and has never overheated. I have also driven it to work on several occasions in stop and go rush hour traffic in downtown Tampa and have never had an issue.

My motor also runs best warmed up. It will run a little rougher and won't pull as strong until it warms up, so I don't see the point in installing a lower-temp thermostat.
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Unread 05-31-2008, 07:50 AM   #11
jfwireless
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I have tried 180, 195, but mine down in this heat just runs better and cooler with the 160. I think it is just were you live. I never need the heater so warming up is not an issue, more like air-conditioning weather, of course I do not have an air-conditioner in my CJ, just doesn't seem right.

When I ran a carburetor, with the 180, 195 on a hot day after shutting the engine down and and starting up again in a few minutes sometimes it would vapor lock, and I did run the return filter with the return line up. Must have been boiling some gas in the fuel bowl. I haven't tried a 180 or 195 with the TBI setup, I doubt I would have that problem with the TBI as it is constantly cycling fuel through the throttle body back to the gas tank.

I understand that a 160 degree thermostat just sets the operating range, doesn't increase the cooling efficiency of the cooling system, but with the 160 I just do not get the large engine temperature swings I do with a 180 or 195. The upper temperature limit also is some 20-30 degrees cooler than with a 195. Most of the time I am in the 170-190 temp range. So running an average temp of 180 seems OK to me. I never get any heat radiating or blowing into the interior.

After running this Jeep since 1976, bought it new, I am happy with this set up, runs best just like it is.

Jim
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