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Just Some Dude in Jersey
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Discussion Starter · #1 · (Edited)
While I've been working on my Opel Motronic fuel injection install, I only recently learned that the oem throttle bodies on these systems are water cooled/heated. We had decided right off the bat to go with an aftermarket throttle, so I spent no time pondering the mysteries of why the oem throttles had so many pipes and hoses sticking out of them. The oem throttle bodies have two water passageways or "jackets" on either side of the throttle body to help warm up the air as it enters the air manifold on cold days.

This got me to thinking about my long held belief that vapor lock and difficult restarting on hot days is due to the carb getting baked, NOT that your fuel is getting heated up on it's way to the carb. I have often thought that a fan blowing at the carb or some sort of water jacket/spacer in place of the phenolic spacers that many down draft carb guys have would be a better way to keep your fuel from boiling.

So now, imagine a slightly bigger phenolic spacer, but made out of aluminum, with water passageways around the perimeter, fed by the water and hoses that make a water choke work. This water constantly circulates when the engine is running and could, theoretically prevent the carb from exceeding the temp of the water in the system.

Since I believe that the heat that's making the fuel boil is coming from the intake manifold soaking up heat and giving it to the carb, which is why the phenolic(insulating) spacers work pretty good at reducing vapor lock, a water jacket could be bolted to the bottom of the intake manifold where the chimney from the stock exhaust used to bolt to.

Open discussion, talk about whatever you want, I just felt like starting a thread......:p
 

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Opeler
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Spacer with circulating coolant are not new. Calling those spacers "water cooled spacer" is somewhat deceiving. Its purpose is to warm-up carburetor and prevent its freezing in the cold climate areas.

Circulating coolant will keep steady temperature of the carburetor when driving but it will not prevent difficult start after the engine has been shut as the carburetor will still soak-up the heat from the exhaust. Hoping that the water cooled spacer will help is not realistic as the water stops to circulate after the engine has been shut.

 

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Can Opeler
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I have no idea if this would help but have you considered Peltier devices on the fuel bowl?

These won’t work. Both sides heat up if you don’t have an excellent head dissipation system. Also the power they draw would offset any benefit.

And Gordo that’s not a water cooled manifold. The coolant is to prevent the manifold from icing.
 

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This is my snowmobile engine. It's a 20 year old, 700cc triple cylinder, 2 stroke, with three carburetors.

There's an antifreeze in series circuit that flows from the water pump threw each carburetor (air box side), to a valve, and back to the cylinder head. In this case it to prevent the carburetors from freezing up and sticking in very cold climates .

You can actually see the hose leaving the carburetors, to the valve on the air box, and the hose leading back to the head on the right side in this picture.
 

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I thought that's what the electric fuel pumps were for so it didn't matter if the fuel boiled off or not
But what do I know I'm still on a mechanical pump.
Pretty sure I just fell into the scifi trap
I just wanted to start a thread LOL Good one my friend good one
 

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Detroit,where my home was
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My wife's Volvo 340 has a special part between the carb and the intake and has engine cooling fluid running thru it
 

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Just Some Dude in Jersey
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Discussion Starter · #8 ·
And Gordo that’s not a water cooled manifold. The coolant is to prevent the manifold from icing.
That's what Gil told me the passages and water were for, to warm the air. But it's the same difference: Warm the throttle body(and air passing through it) and you decrease the chance of icing up as well as providing slightly warmer air to the engine. :)
 

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Just Some Dude in Jersey
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Discussion Starter · #9 ·
Spacer with circulating coolant are not new. Calling those spacers "water cooled spacer" is somewhat deceiving. Its purpose is to warm-up carburetor and prevent its freezing in the cold climate areas.

Circulating coolant will keep steady temperature of the carburetor when driving but it will not prevent difficult start after the engine has been shut as the carburetor will still soak-up the heat from the exhaust. Hoping that the water cooled spacer will help is not realistic as the water stops to circulate after the engine has been shut.

I'm sure that's true, but as it pertains to the unique problem our Opels have with carb boiling or vapor lock while stuck in traffic, a water jacket could potentially limit the temperature of the carb while stuck idling in backed up traffic on a hot day.

Having an automatic car, I'm always in gear and generating heat due to friction when I'm crawling in traffic. I have had to throw it in Neutral and/or rev the engine to 1200-1500 to spin the water pump and engine fan faster and/or turn on my heater and fan to control the heat.

This problem disappeared when I installed the angled single side draft manifold, which moved the carb a lot farther away from the engine and exhaust. I anticipate not encountering this problem with the FI set up I'm installing either. :)
 

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Pedal Smasher
1973 Opel GT
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I don't believe the problem involving vapor lock after shut down is due to the carb soaking up too much heat once the vehicle is parked. Once you shut off the engine, the engine bay will have a momentary increase in temp since no air is flowing through it and then it will start to cool down. I believe the carb has soaked up plenty of heat by the time you shut off the engine and with no more fuel being constantly pumped into it, that heat can now heat up the fuel in the float bowl which will cause it to evaporate. So, putting a coolant spacer between the carb and the intake manifold could do the trick if the water going through it was significantly cooler than the temp of the intake manifold. Even after shut down, this spacer would still be better than the carb being attached to the intake without a spacer but most importantly, it would keep the carb from soaking up too much heat while driving. You could even design it to include a phenolic spacer between it and the intake manifold, so there isn't any significant metal on metal heat transfer. The studs will always be a conduit for heat transfer from the intake to the carb and that can't be avoided but what studs contribute is marginal compared to the whole intake manifold bolted up to the head with the exhaust right there.
 

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The cooling system should be separated from the engine and have its own radiator and electric water pump that circulates the coolant.
A heated manifold doesn't stop carb icing, which happens when the temperature is around 0°C, to stop that you have to mix alcohol in the fuel.
 

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Pedal Smasher
1973 Opel GT
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The cooling system should be separated from the engine and have its own radiator and electric water pump that circulates the coolant.
Or find a way to divert some coolant right before the water pump to the coolant spacer. I'm not sure this could be done however without the pump's suction actually reversing the flow through the coolant spacer, pulling hot water from the thermostat housing. The easiest way to implement this, would be to have it plumbed into the water choke or if an electric choke was used, the same plumbing for the water choke. An inline finned cooler / radiator could be incorporated after the water choke, to cool water down before sending it to the coolant spacer. It wouldn't be as effective as a stand alone system, but it would be easier to install. No separate electric pump, radiator, and reservoir.
 

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Pedal Smasher
1973 Opel GT
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I was doing some reading on carb icing and Hemmings has an interesting article on it...


"...a carburetor will suffer the most dramatic icing when the ambient temperature is between 45 and 50 degrees F–well above freezing."

This of course requires a relative humidity at like 70% or above, enough for the air to be carrying a decent amount of water vapor.
 

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I had a Manta B with a 20S engine once that was very prone to freezing when the temperature was around 0°C if I had forgotten to add ethanol in the tank, and once when the engine stalled due to the ice, I heard a big bang after coasting a while, which was caused when the fuel that had flowed in the first muffler during coasting, suddenly ignited when the engine fired again after the ice melted. But the funniest part was that the muffler split from the blow.
:)
 
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