67 GTX 440 Engine Temperature With AC

[67GTX440]

Hood to radiator seal. Found one in Classic Industries catalog for a 67 B body. How much would this missing impact my airflow through the radiator, or is this like the seal at the cowl that just keeps dirt and water from the engine compartment?

 

[Dennis H]

Hood to radiator seal. Found one in Classic Industries catalog for a 67 B body. How much would this missing impact my airflow through the radiator, or is this like the seal at the cowl that just keeps dirt and water from the engine compartment?

I suspect more about channeling air flow than debris prevention. Part of the recipe. If you get one, be sure to investigate the proper fasteners.

 

[Ranger16]

I suspect more about channeling air flow than debris prevention. Part of the recipe. If you get one, be sure to investigate the proper fasteners.

It IS for channeling air flow, but I found I always had a bunch of those little no see 'em's on the underside of my hood if I drove in the evening. I no longer do so I know it is somewhat effective.

P.S.
It comes with 10 retainers for installation, but you'll have to make your own cutouts.

 

[AR67GTX]

Hood to radiator seal. Found one in Classic Industries catalog for a 67 B body. How much would this missing impact my airflow through the radiator, or is this like the seal at the cowl that just keeps dirt and water from the engine compartment?

I have it on my car. I don't remember noticing any big change when I installed it but my car does run pretty cool with AC. It probably doesn't make a great deal of difference as my radiator shroud doesn't seal all that well to the radiator anyway. But, it can't hurt and it's not very expensive from memory.

 

[Ranger16]

$33.94 from Classic Industries.

P.S.
I saw no change in temperatures after the install, b ut I like not having to clean those damned little bugs off the underside of the hood.

 

[TxDon]

Not sure what the rubber piece is in the picture of your hood. I don't have that on my car. What is its function? To keep the fan from pulling air through the grill but over the top of the radiator? Was there one originally on a 67 GTX?

I think you answered my question, since you have a factory air car you would have one or at least the holes where it was mounted. Another thing the 68 and later cars had was an "air dam" at the bottom to guide air into the radiator - do you have anything like that on your 67?

 

[MarPar]

Very similar climate and issues on same car. I have the Hayden 2947 on order and am going to remove the thermostat to see what temp I get. Currently running straight distilled water with water wetter for anti-corrision since pure water dissipates heat better than a 50/50 water/antifreeze mix. Running factory fan and shroud, a 30 percent higher flow water pump and radiator was just recored. No real heating issues until I reinstalled the condenser and got he A/C up and running. Running a more efficient Sandin compressor.

this may contribute to your problem. if the water runs too fast it will cavitate and not dissipate the heat effectively enough.

what brand of water pump is it? how many blades?

 

[67GTX440]

this may contribute to your problem. if the water runs too fast it will cavitate and not dissipate the heat effectively enough.

what brand of water pump is it? how many blades?

Water pump is a GMB 120-1200P. It has six blades and is supposed to have 30% better water flow than the original eight blade. I have no idea what the GPM flow is on the stock or eight blade or the new six blade water pump.

I keep hearing comments about water running too fast. I have been testing the 180 degree thermostat I plan to install in 180-190 degree water and at full open it does not appear to open much. Does anyone know the GPM flow through an open thermostat? That would have to be the primary point of flow restriction regardless of the water pump. It would seem that the GPM water pump flow should be approximately equal to the GPM maximum flow of the thermostat, but this information seems to be lacking from the manufacturers and is replaced with the phrase "meets or exceeds OEM standards."

My wife was pissed I was testing the new 180 degree Stant Superstat in her toaster oven and melted the plastic rather than glass face on her temperature probe. Who new it would melt from the heat in the toaster oven before the toaster oven heated the water to 180 degrees. I guess you are supposed to take the meat out of the oven and insert the probe to check the temperature, rather than leave the probe in the oven while cooking in a 400 degree oven. Live and learn. It goes with out saying it was passed down to her by her now deceased mother.

I installed the new HAYDEN 2947 heavy duty clutch fan and rolled up a towel into a tube shape with duct tape. I duct taped it where the radiator/hood weatherstrip would go to block any air flow it normally would block. I have one on order and the one I ordered says it comes with the pins mounting pre- inserted.

With the 195 degree thermostat, the car ran about 215 degrees at 90 degree outside temperature with the A/C on an exactly the same with the A/C off. It seemed to run hottest on the highway at 65 and to drop to about 205 degrees if you stopped and let the car just sit and idle. Seems weird, but it seems to run cooler at idle.

I removed the 195 degree thermostat and am going to try running it without a thermostat to get a temperature baseline with none before I install the 180 Stant Superstat. The gasket sealer is setting up as I write this.

So far I have replaced the water pump, fan clutch, radiator hoses, thermostat (195 degree) and had the factory 26" Mopar radiator recored. Car is an original factory air car and has the original seven blade fan and shroud. I have the radiator/hood seal on order.

I am running out of things to try. I will put in the 180 degree thermostat after I get a no thermostat baseline. If that gets things no cooler, I have ordered a second temp gauge and sending unit to rule that out, although both are new. The gauge was installed by tapping the factory plug between where the radiator hoses go into the engine. The factory gauge works, but is a repop that has always shown on the cool side. It is just above the low end of normal operating temperature when the the new gauge reads 215. A probe in the radiator shows the radiator temperature at over just over 200 degrees. The car does not gurgle when stopped or spit any coolant. It did after I got the A/C up and running but quit after I had the radiator recored. I am running straight distilled water and water wetter for anti-corrosion right now until I get this resolved and can add antifreeze. Straight distilled water dissipates heat better than and antifreeze mix although the mix may have a higher boiling point.

I am not aware of any valance on the underside to force air through the radiator on the 67 GTX.

Is there any chance of a blockage in the water pump housing itself? I only replaced the water pump.

I did read a post here where someone found an old freeze plug inside of their engine block causing a blockage. I am not aware of any way to test actual water flow through the block.

this may contribute to your problem. if the water runs too fast it will cavitate and not dissipate the heat effectively enough.

what brand of water pump is it? how many blades?

 

[TxDon]

Great step by step coverage and scientific method approach, anxiously awaiting the final results!

 

[67GTX440]

Water pump flow does appear to facilitate radiator cooling up to a point. The primary flow restriction appears to be the thermostat and radiator. This article indicates that this may cause a sight positive pressure at the upper hose.

Since the water pump flow increases with engine RPM, but this does not facilitate greater flow in the radiator due to thermostat or radiator restriction, the time in radiator for cooling may be a moot point. Whether the positive pressure may cause cavitation is another issue. In a full and closed system with no air, it seems like the flow will be determined by the thermostat or radiator flow capacity. Someone above my pay grade will have to answer this.
It is a 50 year old Plymouth, not a nuclear submarine, and although they are overhead in my area constantly, I have never been picked up by a P3 to my knowledge.
The boys on the boomers tell me they have to create noise for the P3's to find them in training simulations.
The time in radiator question will hopefully be answered when I run the car tomorrow with no thermostat and see if it runs a cooler high temperature.

I have people saying if you want it to run 165, run a 165 thermostat and if you want it to run 180 run a 180. Life would be good should things be that simple. Running 215 on a 195 has proven that to me so far.

Update tomorrow.

Water Pumps
Usually centrifugal pump is used for the circulation of water in the cooling system. Figure 12.7 shows the construction of a centrifugal pump, which is driven by a fan belt mounted on a common shaft with the fan. The centrifugal pump is non-positive in action and does not build up high pressure. It simply consists of a casing inside which an impeller containing vanc-s is rotated. Water enters the inlet pipe from the bottom of the radiator and is directed by a passage to the centre of the impeller where it is caught by the rotating vanes. Due to centrifugal force the water is thrown out into the stationary casing. The kinetic energy imparted to water by the impeller is converted into pressure energy in the stationary casing so that a pressure difference is created between the inlet and outlet of the pump causing forced circulation of water in the system. Since the impeller is always submerged in the water, a seal is used to make a water tight joint where the impeller shaft passes through the casing.

Fig. 12.7. Sectional view of a centrifugal pump.
The water pump on a V-8 engine at cruising speed pumps about 475 litres per minute of operation. Depending on the restriction of the thermostat and radiator, the water pump may create a slight positive pressure at the upper hose. The pump insures an adequate flow of coolant through the water jackets and radiator. The pump usually causes a flow of about 0.3 to 0.6 m/s through the radiator tubes. A slightly higher velocity although produces a greater efficiency in the radiator but causes a higher power loss at the water pump. Coolant flow with a velocity more than 1.8 m/s is considered a waste of power.
The water pump impeller shaft is supported by a double set of ball bearings which are permanently lubricated and sealed. A carbon seal is used to keep the coolant from leaking along the pump shaft. A weep hole in the housing allows any coolant that seeps past the seal to escape from the pump preventing corrosion or damage to the pump bearings.
12.4.2.

 

[Dennis H]

Hood seal picture from a non-ac car fyi.

 

[67GTX440]

Hood seal picture from a non-ac car fyi.

I hope there is no difference A/C to non A/C. The one I order did not have but one 67 B body listed.

 

[Ranger16]

I'm putting my money on the 180 thermostat.
Keep in mind that you still have a 160 in your hip pocket.

 

[WileERobby]

Reading thru this quickly... the seals are there for a reason, whether its hood, lower bumper, etc. , and that is to direct air flow from the grille THROUGH the radiator, and not above the top core support or below the lower support. Fan positioning in the shroud is important. I've run 180's for over 45 years in all my cars, factory fan/clutch/shroud. By the way, how is your air/fuel ratio & your timing ?

 

[67GTX440]

Reading thru this quickly... the seals are there for a reason, whether its hood, lower bumper, etc. , and that is to direct air flow from the grille THROUGH the radiator, and not above the top core support or below the lower support. Fan positioning in the shroud is important. I've run 180's for over 45 years in all my cars, factory fan/clutch/shroud. By the way, how is your air/fuel ratio & your timing ?

I have no idea on the A/F ratio or timing. The car runs great, the exhaust looks clean and it can sit for weeks and fire on the first bump of the starter and immediately go to a smooth idle. I will take a look at these if nothing else resolves the issue, but I am ruling out the obvious suspects first. I am frankly a little hesitant to mess with these unless I know there is an issue. I hate to fix what does not appear to be broke. I will try it with no thermostat tomorrow and see how that goes.
Fan is about an inch from the radiator and probably half way in the shroud. All this should be factory.

 

[AR67GTX]

I was also going to ask about your timing - it can be critical to engine temp. My old BB Corvette operating temperature dropped about 15 - 20 degrees just by switching from factory ported vacuum advance to manifold vacuum. Full vacuum advance operating on manifold vacuum is very important to keeping engine temperatures in check at idle and low speed. Interesting your car seems to idle at cooler temps than going down the road. That may indicate your timing is OK and something else is going on as you suspect.

 

[WileERobby]

Oh, and by the way, you don't test a thermostat in a toaster, LOL ! Put it in a pot of water, and heat the water & watch the opening with a thermometer in the water.

 

[67GTX440]

Oh, and by the way, you don't test a thermostat in a toaster, LOL ! Put it in a pot of water, and heat the water & watch the opening with a thermometer in the water.

A bowl of water in a toaster over, not a toaster. A toaster would have been really stupid! Advice noted and lesson learned. LOL

 

[67GTX440]

Update-

With no thermostat, the car runs right at 200 with the A/C on at 65 and appears to run the same temperature with the A/C off. It appears to drop about 5 degrees at idle at a light to about 195. Stuck in traffic overheating does not seem to be an issue, just the car running hotter than I would like. That is 10-15 degrees lower than with the than with the 195 thermostat. The radiator should now be the definite point of flow restriction rather than the thermostat. This should also tell me a 180 thermostat won't make it run any cooler than it does now without one.

The 180 or lower thermostat solving the problem theory should be pretty much disproved at this point.

The cooling time in radiator of the water may or may not have changed dependent on whether the thermostat or the radiator was the main flow restriction. Since the car is running 10-15 degrees cooler, I would say that the thermostat was the main point of flow restriction and more and faster flow through the radiator is the reason for the temp drop.

The more flow through the radiator from a higher flow fuel pump or removal of the thermostat causing less cooling time in the radiator and higher temperature should be disproved at this point, at least for my setup.

I am out of ideas on the cooling system side, so I am going to look next at the A/F and timing, to see if A/F or timing advance could be the problem. The running cooler at idle seems inconsistent in a Riddle Me Batman sort of way.

I have a Pertronix distributor conversion to electronic ignition and when the engine was rebuilt it was pretty much stock with some minor changes, mostly to better accommodate unleaded gas. I don't know the specifics.

Should timing be the same as the factory manual?
12.5 degrees BTC at set at idle
0 degrees advance at 325 to 425 RPM
0 to 4 degrees advance at 425 RPM
4.5 to 6.5 degrees advance at 640 RPM
8.5 to 10.5 degrees advance at 2200 RPM

Is J-11Y Champion or P3-3P Mopar gapped at .035 still the recommended plug and still available?

 

[Mike67]

Just my 2 cents, but I still think it might be your after market gauge or sending unit... Your factory gauge is still showing normal ??? And you aren't boiling over... Correct? Like I said earlier just swap the two sending unit leads an then see what your reading is...