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322 Nailhead Water Temperature Gauge Range / How to aovid Vapor Lock


Ralph55
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Does anyone know the temperature range of the gauge in 1955 or 1956 Buicks?

My 1955 Super shut down the engine while driving when the temperature reached N (the center position of the gauge). After 20 minutes of cool down the engine started again.

 

When checking the actual temperature of the radiator  (with a BBQ thermometer 😋 ) when the needle pointed to N I found out that's just 150 deg Fahrenheit! With my 66 GTO the regular temperature is 170 deg.

 

I tried to find the water temperature range in the shop manual - but no luck there:

 

temp-gauge.PNG

Edited by Ralph55 (see edit history)
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Water temperature.  Upper limit of the gauge is about 200*F.  Your Super did not shut down the engine...it shut down probably due to vapor lock.  All 55's need an electric fuel pump mounted near the tank due to the highly volatile available fuel.  Check the temp with an IR temperature gun at the thermostat housing.  Temperature will depend first on the thermostat installed and later on environmental temperature.

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Thanks for the hint, Tank 🙂 Never heard of a vapor lock before - but I'm here to learn...

 

I added an electric fuel pump in the engine compartment. What would be the reason to mount it near the tank?

The current thermostat is brand new and was replaced during the engine revision in winter.

 

So when the pump is electrical - can a vapor lock still occur? I think the pump keeps pushing fuel to the carb - even if the fuel between pump and carb is vaporized.

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‘56 was the first yeat for permanent (ethylene glycol) anti-freeze. There was a service bulletin in late ‘56 that explained that with the change, customers were complaining about running hot, because the water temp needle was buried in the red. 

 

Buick engineering’s solution:  Remove the red from the gauge. If it’s not boiling over, it’s not overheating. 

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14 minutes ago, Ralph55 said:

Thanks for the hint, Tank 🙂 Never heard of a vapor lock before - but I'm here to learn...

 

I added an electric fuel pump in the engine compartment. What would be the reason to mount it near the tank?

The current thermostat is brand new and was replaced during the engine revision in winter.

 

So when the pump is electrical - can a vapor lock still occur? I think the pump keeps pushing fuel to the carb - even if the fuel between pump and carb is vaporized.

Vapor lock occurs on the suction side of any pump.  Any pump can push fuel, but cannot always pull fuel well.  An engine compartment mounted pump is useful to prime the carb on a cold engine, but is no better than the stock mechanical pump to prevent or treat vapor lock.

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I believe that the OEM engine thermostat was a 160 degree F unit, unlike the more common 180 degree F units which others used.  Hence, the middle of the "N" range should probably be near that 160 degree temperature.  Which also means that the "H" line will be lower than what came later, too.

 

When a liquid is placed in a low-pressure situation, it vaporizes easier.  Putting the pump at the REAR is closer to the supply tank and can lessen the "low pressure vaporization" issues.  If put near the engine (as many hot rodders used to do), that puts the whole fuel line in the "low pressure" area.  Even hot rodders from the '60s or so put the pump on the frame rail near the tank.

 

Compared to other makes in the middle '50s, Buicks seemed to have more issues with vapor lock on hot days.  Not particularly from engine heat, but from heat radiated from the pavement/road surface the car was driving/parked on.  As Old-Tank has found out, it doesn't take a 8psi electric pump to do the job.

 

You can get an IR heat gun thermometer at Harbor Freight or Northern Tools or similar.  Even the 1000 degree F models are not more than $30.00 now.  MANY uses in the automotive and residential areas of things!

 

NTX5467

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Reflecting on Tank's input and having a look at the new arrangement of the fuel line after motor revision (Image 1) it seems the metal line right over the engine block creates a "grill enviroment" 😁

 

So if the engine heats up it "grills" the fuel inside the pipe over the whole length. Probably the pipe literally soaks up the heat because being made of metal 😱

 

from-pump.jpg

Pump to filter

 

to-pump.jpg

Tank to pump (it's a low pressure one)

Edited by Ralph55 (see edit history)
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42 minutes ago, Ralph55 said:

Reflecting on Tank's input and having a look at the new arrangement of the fuel line after motor revision (Image 1) it seems the metal line right over the engine block creates a "grill enviroment" 😁

 

So if the engine heats up it "grills" the fuel inside the pipe over the whole length. Probably the pipe literally soaks up the heat because being made of metal 😱

 

 

You are correct.  Fuel in that line will probably boil, but a pump mounted back at the tank will push fuel and any vapor into the carb.

That Airtex pump you have is junk.  It will soon fail (how do you spell tow truck?). This Carter Pump is what I use.

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@old-tank the recommended Carter fuel pump P60504 is discontinued. 😪 The successor is P90091 which only makes half of the gallons per hour.

 

Do you think 15 GPH are still enough? The P60504 had 30 GPH...

 

Though the Carter info tells me P90091 is the replacement part for P60504, my guess would be https://outlawspeed.com.au/shop/fmp60430  

Edited by Ralph55 (see edit history)
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  • Ralph55 changed the title to 322 Nailhead Water Temperature Gauge Range / How to aovid Vapor Lock

Electric fuel pumps are a fine "pusher"' but a very weak "sucker". For this reason, your supplemental electric pump should be mounted in-line as low, and as close to the fuel source (tank) as reasonable.

Some also recommend adding a relay from your oil pressure switch so that if the car is stalled, you'll not flood the carb -

or if the car is in a wreck and the engine quits, you'll not be adding fuel to a possible fire-

Overkill? - maybe, but as a son of a career firefighter I believe in precautions.

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Oh... after a quick check: I didn't install the safety relay a year ago - because I couldn't find the oil pressure switch back then 😬

 

After doing some research I think there is only an oil pressure sensor for the gauge - but no switch because there's no separate warning light.

I found one article on how to "retrofit" the 322 with an electric oil pressure switch using  the 'little tapped hole just above the oil filter mount'.

 

Do I have to get an oil pressure switch or would it work if I just attach the wire of the relay reading "to oil pressure switch" to the pressure sensor? 

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THIS would be easier than installing a "T" fitting and then trying to fit lines in that very inaccessible location.  

On 8/20/2019 at 7:44 PM, Marty Roth said:

Some also recommend adding a relay from your oil pressure switch so that if the car is stalled, you'll not flood the carb -

Even when installed it seem that you will have not power to the fuel pump until the engine is running...seems there would have to be a "momentary switch" to bypass??

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2 hours ago, old-tank said:

THIS would be easier than installing a "T" fitting and then trying to fit lines in that very inaccessible location.  

Even when installed it seem that you will have not power to the fuel pump until the engine is running...seems there would have to be a "momentary switch" to bypass??

 

Needs to be installed like a 1990s era FoMoCo setup so in the event of a crash the fuel will not be pumping to support a blaze

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After a 20 miles highway drive I sampled the temperatures along the fuel path - it turned out the fuel is probably boling inside the metal fuel filter close to the carb which draws heat from the engine block obviously!

 

As there are two filters (one is right after the pump) I'll remove the one right before the carburetor. To avoid the fuel boils inside the carb bowl I'll add an additional insulating base gasket for the Carter WCFB.

temp-samples.PNG

Edited by Ralph55
typo (see edit history)
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2 hours ago, Ralph55 said:

After a 20 miles highway drive I sampled the temperatures along the fuel path - it turned out the fuel is probably boling inside the metal fuel filter close to the carb which draws heat from the engine block obviously!

 

As there are two filters (one is right after the pump) I'll remove the one right before the carburetor. To avoid the fuel boils inside the carb bowl I'll add an additional insulating base gasket for the Carter WCFB.

It won't make any difference.  A pump back at the tank will push fuel and any vapor along into the carb.  Now an attempt at insulating the base of the WCFB might be of some benefit to address percolation (fuel boiling in the carb and flooding the manifold) after a hot run.  But if using the stock air cleaner assembly, there is not enough room between the hood and air cleaner for anything too thick.

Hey, I tried all of those remedies, including clothes pins on the fuel line:  vapor lock occurs on the suction side only!

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Sorry,  I did forget to mention that my Carter pump arrived from the US yesterday and I'll replace the Airtex in the engine compartment with the Carter back at the tank. Great thing aside: Because amazon International couldn't meet the delivery date they didn't charge shipping - so the pump was really a bargain... 😁

 

But are you really sure with the suction side?  At 1:54 it''s boiling between pump and carb -->

 

 

Edited by Ralph55
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32 minutes ago, Ralph55 said:

But are you really sure with the suction side?  At 1:54 it''s boiling between pump and carb

Yep, really sure!  The pump at the back will push all that into the carb and it will continue to run fine.  And get rid of all that rubber and plastic chit and replace as much as possible with metal.  It makes me plumb sick when someone becomes a crispy critter.

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I'm not running a separator. Bypassed the mech pump. The brass tee has pipe thread fittings so there is a nipple to pipe thread on the inlet. Outlet to carb is a union pipe to pipe thread. On top the return line to tank is a pipe to Swagelok 1/8" tubing.  The constant gas flow keeps it cool. Have had zero vapor lock since this upgrade. I now have stainless 1/8" return line for durability. I drilled a 1/8" hole high in the filler neck for return. 

Good luck!

Phil

 

carb.jpg

carb2.jpg

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