1955 runs hot- water pump smaller diameter pulley

[jack-in-sac]

Do yourself a favor remove the thermostat and drive the car with out it let it idle and drive it on a hot day the car should run at lower temperature and if this fixes your problem put a 160 degree thermostat in it and be done. Y blocks don’t have any overheating problems they have been used in cars and trucks up to 1964

In this situation a temporary check can be a good idea. The smaller pulley if moving coolant through the radiator faster does not make things cooler. The coolant moving faster just returns coolant that is less cooled by less time to give off heat from air flowing across the radiator surfaces.

 

[Joe lemay]

Advice wanted: Some articles I've read mention that below 850rpm's there is little water flow even with the high output water pump, modified spacer and big mouth thermostat. Some suggest replacing the stock water pump pulley with a smaller diameter pulley. Has anyone changed out the stock water pump pulley with a smaller one and if so what diameter would you recommend? Did it help? Did you have to use a smaller fan belt?

Thanks in advance.

 

[Joe lemay]

Still putting my 55’ together and adding a small foreign car recovery tank to scavenge boiled over water back in to prevent air pockets high in the motor hoping to keep temps down.
Once on the road I’ll report in .

 

[Ward 57]

In this situation a temporary check can be a good idea. The smaller pulley if moving coolant through the radiator faster does not make things cooler. The coolant moving faster just returns coolant that is less cooled by less time to give off heat from air flowing across the radiator surfaces.

I don't know why you keep on insisting this. The whole reason new pumps have been designed and bigger thermostats to increase the flow. The radiators are big enough you just have to get the heat out of the engine faster so no hot spots.

 

[jack-in-sac]

I don't know why you keep on insisting this. The whole reason new pumps have been designed and bigger thermostats to increase the flow. The radiators are big enough you just have to get the heat out of the engine faster so no hot spots.

Well I guess I am just stupid. No more comments on this from me. Thank you for correcting me.

 

[Ward 57]

Well I guess I am just stupid. No more comments on this from me. Thank you for correcting me.

You are not stupid. Fluid dynamics are sometimes not easy to grasp. Just as radio waves and cell phones are a black science but I have been in the field, literally and understand the physics.

 

[zeroroadkill]

Don’t know why I didn’t ask this before. My ‘55 has a chrome water pump pulley which I’m sure isn’t stock???

Can anyone with a stock’55 water pump pulley measure the circumference, diameter or the radius, (which ever is easier), so I can compare mine?

Thanks

 

[Tom Alpers]

Well I guess I am just stupid. No more comments on this from me. Thank you for correcting me.

It's a common thought and while it is not correct there was a time when it seemed correct for at least some vehicles... so you're not stupid, it was common wisdom, and for good reason, at one time. The main reason it sometimes was seemingly correct was due to how some vehicles had the radiator bypass set up... when the thermostat was removed the natural thinking was that that allowed more flow (it did) AND it was thought that flow was thru the radiator. But the flow was actually bypassing the radiator and the car would run hotter. People naturally thought the water was going too fast thru the radiator when it was actually bypassing the radiator. It is, in fact, true that if you have super high flow (well over 3 times the flow our tbirds will ever have), as some race cars do, there can be an issue of the water going "too fast", i.e. laminar flow and not enough tumbling action thru the radiator tubes. They make tubes with a rough inside to break up the laminar flow so the problem doesn't happen in those cases.

 

[zeroroadkill]

Ok, if you follow my threads on over heating I have tried everything I can think of. New 4 core radiator, modified water pump spacer, 6 blade fan, high flow water pump, 7 gaskets under the carb, insulated fuel lines, electric fuel pump, vented gas cap, and she still doesn’t like stop& go traffic on warm days! I get stumbling and vapor lock when the temp gauge goes towards the right past normal 90% normal driving. We Did a 130 mile trek today at 80° and ended up in stop & go traffic at the end and she started hesitating again. I thought I had it licked, but I guess not!
Has anyone had this problem ( as 292cid engine’s run hot) resolved this problem with an electric fan in front of the radiator? I’m at my wits end!

 

[Tom Alpers]

Ok, if you follow my threads on over heating I have tried everything I can think of. New 4 core radiator, modified water pump spacer, 6 blade fan, high flow water pump, 7 gaskets under the carb, insulated fuel lines, electric fuel pump, vented gas cap, and she still doesn’t like stop& go traffic on warm days! I get stumbling and vapor lock when the temp gauge goes towards the right past normal 90% normal driving. We Did a 130 mile trek today at 80° and ended up in stop & go traffic at the end and she started hesitating again. I thought I had it licked, but I guess not!
Has anyone had this problem ( as 292cid engine’s run hot) resolved this problem with an electric fan in front of the radiator? I’m at my wits end!

On the factory gauge, when everything is "factory spec", the top of the white arc is around 190 degrees. The "hot dot" itself is 212 degrees. With the correct radiator cap and 50.50 mix of coolant you won't get boiling till it goes past 250 degrees. Of course, it is possible you could get vapor lock even if the engine isn't overheating. If you are getting vapor lock it may be you have a weak fuel pump. I have an electric backup pump on mine in case the mechanical fails and also in case it starts to vapor lock. I've had it start to vapor lock and I kick on the electric pump, and it immediately clears up.

You said earlier it ran at the end of the arc and sometimes a bit past it. To me that is not overheating and on a modern car with that temperature the gauge would have the needle right in the center and no one would give it a second thought. Also, when you think the car is overheating what happens when you shut it off? If there is no noise of boiling water in the engine and no water coming out the overflow in the first couple minutes after you shut it off when you think it's overheating, it's probably not overheating. Did you ever get an actual measurement of the temperature at the thermostat housing? Until you do that you are very possibly chasing ghosts. I have roughly the same setup you do plus AC. It never overheats but it will, on a hot day, push the factory gauge needle up between the end of the arc and the hot dot. That's the nature of these old temperature gauges, the peg at about 220... modern cars put 220 near the middle and don't peg till 260... we're all used to seeing the needle in the middle and when its way up toward the end it's just psychologically a bad feeling.

All that said, if you find it really is running hot, say approaching 220, it may be your distributor timing is set incorrectly or the loadamatic vacuum advance from the teapot is not working correctly.

 

[zeroroadkill]

It does run normal temperature, around 60% on the gauge most of the time. Climbing hills or on hot days in traffic it will go 90%. Digital temperature reading about 190°. So maybe NOT overheating but causing vapor lock @ 90% on the gauge. Because most replacement mechanical fuel pumps are Chinese junk, I bypassed it with a CASCO electric pump witch puts out from 2.5-4.5psi. Like I mentioned I have insulated the fuel lines and have 7 gaskets under the carburetor (stock is 5). Fuel filter new, bowl clean of debris, carb input filter/screen clean, new fuel tank and flushed fuel lines. Timing is set to factory specs (6° BTDC). Not sure what else to do.

What is the psi output of a factory mechanical fuel pump?

 

[Brax]

Advice wanted: Some articles I've read mention that below 850rpm's there is little water flow even with the high output water pump, modified spacer and big mouth thermostat. Some suggest replacing the stock water pump pulley with a smaller diameter pulley. Has anyone changed out the stock water pump pulley with a smaller one and if so what diameter would you recommend? Did it help? Did you have to use a smaller fan belt?

Thanks in advance.

These cars should have a 160 deg thermostat for the summer and a 180 for winter I have never had a problem with over heating. If the radiator is clear and clean there is no problem with stock water pump and radiator. If you only drive in the warm months leave the 160degree in also put the correct radiator cap on I believe it is 8 or 9 lb cap(from memory)

 

[doug7740]

It does run normal temperature, around 60% on the gauge most of the time. Climbing hills or on hot days in traffic it will go 90%. Digital temperature reading about 190°. So maybe NOT overheating but causing vapor lock @ 90% on the gauge. Because most replacement mechanical fuel pumps are Chinese junk, I bypassed it with a CASCO electric pump witch puts out from 2.5-4.5psi. Like I mentioned I have insulated the fuel lines and have 7 gaskets under the carburetor (stock is 5). Fuel filter new, bowl clean of debris, carb input filter/screen clean, new fuel tank and flushed fuel lines. Timing is set to factory specs (6° BTDC). Not sure what else to do.

What is the psi output of a factory mechanical fuel pump?

According to the service manual, the fuel pump pressure specification is 4.0 to 5.0 psi at 900 rpm and you said that your electric fuel pump puts out 2.5 to 4.5psi. That would lead me to believe that you have a defective fuel pump.

Did you perform a fuel volume test on your new fuel pump? The volume specification is 1 pint in less than 45 seconds, at 900 rpm.

doug7740
1955 Thunderbird Blue

 

[Tom Alpers]

Alternate opinion: There was a reason automakers stopping installing 160 thermostats.... Running a 160 thermostat promotes oil dilution and contamination and also increased wear. A 180 should be used year-round.

 

[ron56]

My idea would be to install a fuel pressure gauge and note the pressure during your problem times. That will tell you where to look and what not to look for. If the pressure stays up during that time then no need to worry about the fuel pump or vapor problems.

 

[zeroroadkill]

Good point, I think I’m going to try a fuel volume test (1 pint in 45 sec) and install a pressure gauge to insure I’m getting 4-5psi 👍🏼