Best high flow thermostat for a 1970 440?

Northcoast300h

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Last year, Car had a Motorad 195F, then I tried a Gates 195F thermostat. Over 85F, car was running at 210F (225F in traffic), so I put a 180F Summit thermostat in. Over 85F, it runs at 200. (210F in long traffic). I kind of understand why the drop, since thermos start to open at that rated temp and are not fully open until 5 or 10 degrees hotter, plus rated opening temp is not accurate, but whatever, I was happy.

My problem is now when weather gets under 60F, it runs at 160F. It warms up to 160F within 5 minutes so I think thermostat is working properly.... or is it stuck open?

Mr Gasket has a high flow 180F thermo, but gets bad ratings for sticking closed. I could not find any RobertShaw and Stewart rated at 180F for a 440. So is there a real "High Flow" 180F thermostat for the 1970 440? Some say High Flow, but measurement of opening is still 1.125" just like standard, so how is it high flow?

PS - I guess I can try the 195F RobertShaw High Flow 1 7/16" opening since they say 195F rated opening temp very accurate and it fully opens at 195F, but after trying a Summit and then a Gates standard 195F thermostats, afraid car will run 225F.

Thanks for any help!
 
Back in the day, people in cooler climates would change out their thermostat depending on the season. 190F in the winter then back to 165F for the summer.
 
The old "Robert Shaw" brand of thermostats was used OEM by Chrysler for many years. Then the company got sold to another entity, back then, and Chrysler went to the normal style of thermostat, with no real issues that I recall. So, the "normal" style should work good enough, by observation, as that style is OEM with GM and such, "forever". Over receent history, the "Robert Shaw style" thermostat has resurfaced from a few sources, from Mr. Gasket first, as I recall, then a few other "performance" vendors, even OReilly Auto Supply.

"High flow" can NOT always be your friend. Having the coolant flow too fast will NOT let it absorb enough heat for transfer to the radiator . . . as there is a window of opportunity for such flows to work best. In my case, I goT a reman pump for my Camaro 350 that was an aftermarket casting, with smoother inner casting surfaces, even a bit larger, and all the time it was on the car, the needle on the temp gauge ran 1 needle-width higher than it did with the OEM-casting pump that had been on there and the OEM-casting pump that replaced it. Just my experiences.

If the car is running a bit warmer in traffic at higher ambient temps, two things. The lower parts of the radiator can be getting clogged (although things look fine through the filler neck) AND similar with the lower sections of the coolant passages is the rear of the block, where everything settles out. So two things for consideration.

The OEM t/stat was a 195 degree F thermostat, although by 1972, Chrysler had gone to a 185 degree F thermostat OEM, although this was a short-lived item. So, pick your choice of temps, either 180 degrees F or 195 degrees F, although most would probably choose the 180 item. Do determine of the fan clutch is doing all that it can, too, as to the higher temps in traffic.

For additional diagnostics, you might get a infra-red heat gun thermostat to check coolant system temps. Top, middle, bottom, and hose temps at the radiator. Cyl block temps, front to back, top to bottom, rh to lh to look for patterns, too. Plus at the thermostat housing.

Things might not really be as dire as they might seem. KEY thing in the coming months is that the heater works well.

Just some thoughts,
CBODY67
 
Last year, Car had a Motorad 195F, then I tried a Gates 195F thermostat. Over 85F, car was running at 210F (225F in traffic), so I put a 180F Summit thermostat in. Over 85F, it runs at 200. (210F in long traffic). I kind of understand why the drop, since thermos start to open at that rated temp and are not fully open until 5 or 10 degrees hotter, plus rated opening temp is not accurate, but whatever, I was happy.

My problem is now when weather gets under 60F, it runs at 160F. It warms up to 160F within 5 minutes so I think thermostat is working properly.... or is it stuck open?
I would stay with the current thermostat unless it's causing your engine to run rich and fouling spark plugs.
 
Sounds like the T stat is working properly.

Cover part of the radiator with cardboard in cooler weather so it will run a bit warmer. Works at my house.
 
I did notice a drop in MPG and a black exhaust while running at 160F (power seems the same), so one last try. I've bought MotoRad 2006-195F high flow thermostat but what cbody67 said makes sense. These openings are up to 50% more over OEM. Maybe the standard 180F one I have in there is sticking open. I'll play around with it over the next year.

Car was abused before I got it. Engine is tired. I've replaced every part of the cooling system, checked the heat riser was not stuck closed, cleaned out 2 rear freeze plugs I could get to (or whatever they're called) and there wasn't much gunk in there, and even removed the cowl rubber so the fan would blow the hot air out of the engine bay. With standard 195F thermostat last summer, my heat gun was picking up the heat from exhaust manifold (700F), so anything near it was wrong, but all other areas of engine were all 205-220F. Maybe 195F thermostat was only partially opening? I thought worn valves and timing system had something to do with the heat, but its running at 160F now, so maybe not?

If that fails, I'll do what 413 said....but with my memory, I'll forget to remove it in summer.

Thanks for everyone's help!

(pic was when it was 93F degrees outside running the old 195F thermo. (aftermkt temp gauge said 215F degrees)
Screenshot-3.jpg
 
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Black smoke is bad, needs more heat as you know.

Where are you pointing the temp gun to show the 185? Should use the WP housing thermostat area.
 
Thanks for the additional information. Engine thermostat temp should not affect exhaust system "smoke".

Agree, black smoke is bad and indicative or an automatic choke not opening fully for some reason (vac break/choke pull-off needs adjusting or is not working, automatic choke thermostat is adjusted too rich or needs some tweaking leaner). Not to forget that the spark plugs are getting sooted-up, too. Might check the (metering rods, if an AVS) primary jets in the carb, too. And the air bleeds in/near the primary venturi cluster.

Possibly the air cleaner is a 1974 model or so which will accept a hose to go to the radiator area for cooler intake air?

Just some thoughts,
CBODY67
 
Get a manual choke carb, IFF you're comfortable using one. I get sooty exhaust when running the morning warmup the first 30 seconds or so, then I open my choke and let Gertrude have plenty air, save on VERY cold days. I also just changed my air filter, which did nicely for improving Gertrude's running well enough to stop the "head cold sneeze" she demonstrated while running at sub par temperature. I run a Mr. Gasket 180F stat, and once Trudi warms up enough, to around 190-200F, she is ready to produce "That Highway Sound" rather like Old Maybellene in the rain. (Truth is, I reckon Trudi could spank Old Chuck's Ford pretty smart, rain or no.)

I pulled the mech fan OFF for the cold season here, running just the electric pusher when needed. This helps reduce warm-up time a fair bit. My fan is nicely clutched, a 7 blade, 18" Mopar 2.25" fan from the early 1970s which helps keep things cool on summer daze, but just robs Gertie of power at higher revs and maybe overcools the system in cooler weather. When daytime high temperatures stay below 80F, we have NO need for the mech fan, with that treasure of an old radiator we have.

225F would worry ME, but if you can cruise along at 200F, then I'd say you have an ideal thermal setup.
 
Interesting cold air intake which I presume isn't factory. If I may, what kind of tube is that and where did you get it?
The great Ebay wonderland. Some cheap rice burner cold intakes. I think they were 3" X 4ft but not sure. It was a long time ago. I think all old carb cars should have something like this. No more loss of power when fully heated up or too hot outside. Seems like a bump in power over 30mph due to forced air, but never had it tested, so maybe just my imagination.

If you do this, you'll need to weld the inlets to the frame, weld fencing inside the inlets and slightly play around with your carb settings. Even so, you'll get more crap in the filter housing, so I'm cleaning it out every 2000 miles. Odd that there hasn't been any problems in rainstorms.
IMG_1278.jpg
 
Thanks for the additional information. Engine thermostat temp should not affect exhaust system "smoke".

Agree, black smoke is bad and indicative or an automatic choke not opening fully for some reason (vac break/choke pull-off needs adjusting or is not working, automatic choke thermostat is adjusted too rich or needs some tweaking leaner). Not to forget that the spark plugs are getting sooted-up, too. Might check the (metering rods, if an AVS) primary jets in the carb, too. And the air bleeds in/near the primary venturi cluster.

Possibly the air cleaner is a 1974 model or so which will accept a hose to go to the radiator area for cooler intake air?

Just some thoughts,
CBODY67
When I stick my hand inside the exhaust, its black. Running, its clean except if I punch it, then some dirty black/grey color comes out. If I keep punching it, then the exhaust is cleaner. Not sure if that normal, but car runs good, no stumbliing, shaking and I can start driving right after I start it, even at 30F. It never stalls. However this engine should really be overhauled since it probably has over 200K on it, but don't have money for that. Carb is new and choke opens perfectly. I know I have the metering rod putting more fuel in, but it starts/runs much more smoother that way. Air cleaner is original. I have an electric fan pusher, plus a new mechanical OEM fan.

I got the Motorad "high flow" thermo in today, but it looks like the same opening as original, so I guess I just have to play with different thermostats until I get it dialed in. Thanks for your help.
 
Thanks for the additional information.

In the prior "leaded fuel eras", it was normal for the tail pipes to have a light gray color in them, unlike the black, sooty look of current eras. I wondered about this. I knew the gray color was normal and if the pipe was black internally, it meant the carb was running too rich, even to the point of black exhaust smoke.

In 1977, I had purchased my new '77 Camaro 305 and it consistently had a black color on the inside of the exhaust pipes. Yet it was running well and was averaging over 17mpg average in my driving. I inquired with our service manager about that. He asked what was not in unleaded gasoline that was in leaded gasoline. I replied "lead", to which he said it was the lead in the fuel that put that gray coating on the inside of the exhaust pipes. With that realization, I didn't worry about the color of the inside of the end of the tail pipes again, on anything. Unless I could see "black smoke" coming out of the pipe.

During the engine's "warm-up" phase, a good bit of condensate is produced as the pipes are warmed by the hot exhaust gases. Whatever is inside the pipes can be wahsed out. Some engines make more than others, by observation. If the engine is idled a good bit before driving off, more condensate will usually come out.

ON THIS NOTE, all Chrysler OEM mufflers (and many OEM-spec replacements) have some small holes on the bottom of the exhaust system. One toward the rear bottom of the muffler and another one near the bottom of the very rear pipe at the low spot before the pipe turns up before the final turn-down exit, a few inches from the pipes end. These are condensate drain holes. The one in the muffler is there for obvious rust-preventative concerns. The other one at the very rear for similar, but for the rear pipe/resonator section. If you let the engine idle for a good while during warm-up, especially in colder weather, you can see the holes work.

On a realted note, the last Walker Exhaust muffler I put on the '67 Chrysler had some literature with it that stated it had some sort of "magic" absorbent material costing the bottom of the inside of the muffler. There to collect any moisture so it could be evaporated by the hot exhaust gases after the engine was warmed-up. I could tap the bottom of the muffler and it sounded "dead", compared to other mufflers I had done that to. Seems like there was also a "Lifetime Rust-out Warranty" too? Guess it has worked as it's till under there after 30 years of limited use.

One time, about 10 years ago, I started to notice (on new Toyotas at work) that they seemed to produce a LOT of condensate. The ones I was seeing had been idling (from cold, after being outside) for a good bit, when they were pulled outside, the first throttle application resutled in up to about a CUP of condensate out the rear of the exhasut pipe. Being they were new, the water was clean.

DO check the automatic choke thermostat to see that it manually closes the choke valve with everything at ambient temps (engine, especially!) of 68 degrees F (which might mean the car needs ot be in a warmed garage in this season of the year in North America). JUST fully closes by itself. If needed adjust the choke thermostat, to get this. Then, as the engine starts, make sure the choke pull-off is doing its job, too. If needed, it can be adjusted to widen the adjustment link in the pull-off's shaft, with a wide-blade flat screwdriver, carefully. If this adjustment is a slight tad "lean", no real problem, but the link can be shortened (usually NOT needed) with a pair of pliers, too.

With that "generally as lean as it will run decently well" choke calibration, plus some tinkering with the fast idle speed screw (where the last step on the cam results in no significant fast idle speed increase over hot base idle speed), the choke should be off after the first mile (or few blocks) of driving. There might be an initial "bog" or "want to die" moment, but that can be "caught" by quickly putting the transmission in "N", followed by a quick "pat" of the accel pedal, then quickly putting the car in gear and driving off. This is where the choke pull-off link adjustment is used to fine-tune the choke's initial operation.

END RESULT is that the choke comes off, or at least off of the highest fast idle step as soon as it can while still having good non-bog drivability. And, relatedly, fewer exhaust emissions and better warm-up fuel economy as the engine is running more toward it's best fuel calibration in those times.

NOW, spark plug gap design can affect these things, too, but can be done with normal-gap style plugs. Just that the NGK V-power and later "fine wire" plugs put more of the spark kernel exposed to the air/fuel mixture for a better "POW" when the mixture is ignited, being more tolerant of leaner mixtures (as the Toyota pamphlet I found, which is where I learned of
"V-gap" plugs initially, made by NGK, OEM to Toyota and later learned of them as "V-gap" NGK plugs). Although the V-gap and fine wire electrodes work well as is, you can also get close to them by filing the ground electrode back so that it only covers 1/2 of the center electrode of teh spark plug ("J-gap" as Champion called it back in the 1960s, for "racing plugs") or hold the plug firmly in one hand as you use a pair of pliers to gently turn the ground electrode so that it only covers 1/2 of the center electrode, without changing the gap dimension (I stared doing this on my lawnmower spark plugs).

Sorry for the length, but wanted to mention my orientations on my tweaking away from "factory specs" and how they worked for me. Not everybody may want to do these things, which I fully understand. OR should attempt these things, by observation. BTAIM

Of course, when the ceramic of the spark plugs is beige-to-white, but not flaky white, then the main system fuel calibration is "in the ballpark" as to working well. Absent of the prior indicators of end-of-the-exhaust pipe internal coloration, correctly reading the spark plugs' ceramic can be more important.

Enjoy!
CBODY67
 
Thanks for the additional information. ....
NOW, spark plug gap design can affect these things, too, but can be done with normal-gap style plugs. Just that the NGK V-power and later "fine wire" plugs put more of the spark kernel exposed to the air/fuel mixture for a better "POW" when the mixture is ignited, being more tolerant of leaner mixtures (as the Toyota pamphlet I found, which is where I learned of
"V-gap" plugs initially, made by NGK, OEM to Toyota and later learned of them as "V-gap" NGK plugs). Although the V-gap and fine wire electrodes work well as is, you can also get close to them by filing the ground electrode back so that it only covers 1/2 of the center electrode of teh spark plug ("J-gap" as Champion called it back in the 1960s, for "racing plugs") or hold the plug firmly in one hand as you use a pair of pliers to gently turn the ground electrode so that it only covers 1/2 of the center electrode, without changing the gap dimension (I stared doing this on my lawnmower spark plugs).

Sorry for the length, but wanted to mention my orientations on my tweaking away from "factory specs" and how they worked for me. Not everybody may want to do these things, which I fully understand. OR should attempt these things, by observation. BTAIM

Of course, when the ceramic of the spark plugs is beige-to-white, but not flaky white, then the main system fuel calibration is "in the ballpark" as to working well. Absent of the prior indicators of end-of-the-exhaust pipe internal coloration, correctly reading the spark plugs' ceramic can be more important.

Enjoy!
CBODY67

All your advice gets covered in sundry FSMs on carb adjustments, or the old Chrysler "Tech" videos. I actually diddled that BBD auto choke for a week or so with surprisingly good result before the major lung and throat surgery this October. You do a very nice job of succinctly instructing folks on the pull-off link and fast idle stuff.

All Things considered, I prefer to just set a manual choke cable to control that butterfly, but my old cable got mighty stiff after the little fire this summer. Still, manual chokes aren't for everybody.

Uncle Tony does a video on "side-gapping" plugs for that bigger bang. I tried it for a bit this past Spring, and it might have helped a bit, though by then my old 516 heads valve misguides leaked enough oil into my bores to foul things up regardless after a kilo-mile or so....

I plan to try old style Bosch platinum plugs with the upgraded setup, and landed a nice stash of those. I understand that the heat of these compares to a range of Champion plugs from about the J11-13 range, making them GOOD summer plugs. I'm still running J14s right now, for the cooler weather, with good result.
 
Thanks Cbody and everyone else. I took out the 180 thermostat and tested it. It starts to open right at 180 and fully open at 190F, so I put it back. My cheap infrared gun said 165F when the thermostat opened up (top rad hose became hot). My cheap 20yr old JCW gauge said 125F. So both are not accurate. I'm guessing its just the 20yr old cheap sending unit went bad, correct, or is it the cheap gauge?
 
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Thanks Cbody and everyone else. I took out the 180 thermostat and tested it. It starts to open right at 180 and fully open at 190F, so I put it back. My cheap infrared gun said 165F when the thermostat opened up (top rad hose became hot). My cheap 20yr old JCW gauge said 125F. So both are not accurate. I'm guessing its just the 20yr old cheap sending unit went bad, correct, or is it the cheap gauge?

Cheap gauges can only be relied on to give WRONG DATA. Toss that junk and get a good Stewart Warner for ~$60, or an AutoMeter one for about $80. I copped a new SW from Scummit, checkec it against my IR gun, a good kitchen thermometer, and the fan switch, and it passed all three of these measuring instruments with VERY consistent results. I like best THICK capillary tubes for temp gauges, as these respond quickly, last longer and give more consistent readings. I use the idiot lights also, as a fallback, but I never like to rely on electrical instruments when it can be helped.
 
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