TODAYS GASOLINE
I am curious....Is there an additive that can be used with todays gas to help
prevent it from VAPORIZING at higher temps.
I have encountered problems when the gas enters the CARB and either the heat shield
or the exhaust flange (heat riser) is not sufficient to reduce heat build up in the CARB.
The gas VAPORIZES and the car will NOT start again or run till the car cools down.
An electric fuel pump is NOT a solution because it just continues to deliver gas to a heated carb and it continues to VAPORIZE.
prevent it from VAPORIZING at higher temps.
I have encountered problems when the gas enters the CARB and either the heat shield
or the exhaust flange (heat riser) is not sufficient to reduce heat build up in the CARB.
The gas VAPORIZES and the car will NOT start again or run till the car cools down.
An electric fuel pump is NOT a solution because it just continues to deliver gas to a heated carb and it continues to VAPORIZE.
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Comments
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Try a pint of diesel fuel or Marvel Mystery Oil per tankfull.
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Sta-Bil will help and should be in any collector car all the time if it is not driven on an almost daily basis. Ethanol is an evil joke from the politicians.0
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AS SAM SAID MARVEL WORKS GREAT FOR ME
YOU CAN ALSO INSTALL A ELEC. FUEL PUMP TO BOOST THE GAS LINE PREASURE AND IT WILL NOT VAPOR LOCK THAT IS WHAT I DID ON MY 50 HUDSON CV0 -
This is a tinkering idea but what about a small electric fan wired into the car and aimed at the carb? I dunno0
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Aaron D. IL wrote:This is a tinkering idea but what about a small electric fan wired into the car and aimed at the carb? I dunno
My buddies 89 Bronco (300 six) had a small blower and ducting that cooled off the injectors after shutting off the engine. It ran for maybe a couple minutes after shutdown. Nice little blower too, might keep an eye out for one in the junk yards on the FI 300 Ford sixes.0 -
Talk to anyone that had a carb rebuilt by Walt. I have a fix that makes all cars start right up after it has be shut off hot. I can drive 500 miles in hot weather, stop at rest areas, get in and start right up and on the way. Walt.0
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OK Walt I'll bite, what does it take? I have a 776S on mine.0
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And I'll bet you are keeping this FIX to yourself....
By the way that isn't the problem....The problem is that the FUEL VAPORIZES.
You can actually watch it turn to vapor as soon as it enters the HOT CARB.
Soooooooooooo unless you can alter the GAS I don't think that there is a mechanical
rebuild on a Carb that prevents this, but please enlighten me and everyone else.0 -
Tom. Silly question, but how thick is your gasket stack between the carb and manifold? I bought a Hudson years ago that had a similar problem. Turns out the previous owner had forgot to replace the stacked gaskets at some point when the carb was removed or rebuilt. I put in a stack of gaskets and problem was solved.0
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TOM-WA- wrote:I am curious....Is there an additive that can be used with todays gas to help
prevent it from VAPORIZING at higher temps.
I have encountered problems when the gas enters the CARB and either the heat shield
or the exhaust flange (heat riser) is not sufficient to reduce heat build up in the CARB.
The gas VAPORIZES and the car will NOT start again or run till the car cools down.
An electric fuel pump is NOT a solution because it just continues to deliver gas to a heated carb and it continues to VAPORIZE.
Tom
Vaporizing gasoline in a carburetor is due to too high a heat for the vapor temp of the fuel. To prevent vaporization and subsequent vapor lock, the fuel delivery to the carburetor must be constant pressure. The pressure will vary due to several factors and you will have to make a determination if these factors fit your particular problem.
The fuel pump pressure should remain at the recommended pressure when the engine is running and when the engine is shut off. Test the pressure of the pump, constant pressure will keep the delivery line full of gasoline and there for prevent space for it to vaporize.
The needle and seat in your carburetor must function as described in the Hudson manual and keep the fuel in the carburetor from draining into the manifold as well as keep the fuel pump pressure from overpowering the needle and flooding the carburetor.
As mentioned in a previous post the carburetor is designed to have a heat shield as well as a gasket stack between the carburetor heat shield and manifold. The stack count is 5 under the carb, then the heat shield and five under the shield between it and the manifold.
Aside from these points of concern... the ability of a 6 volt equipped Hudson to successfully start when hot includes a properly charged battery that spins the starter at proper speed. This requires a right sized battery cable from the solenoid to the starter along with clean terminals and good tight connections.
Test for vapor lock in the following manner:
After the car is hot... take a small rag and wet it, place the rag on a zip lock bag of ice to chill it. Using the chilled rag, cool the fuel line to the carburetor. If the engine starts... the fuel is vaporizing between the pump and the carburetor indicating incorrect fuel pressure. If the initial test does not work repeat test, cooling the fuel pump with the rag. If the car starts the fuel pump is vaporizing the fuel.
No guarantees, but some means to test for the source of your problem.
The Fuel oil to gas ratio generally used is 20 to 1.
Good luck0 -
You can also wrap insulation around the fuel line from the pump to the carby to keep it cooler. Regards, Barry0
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If you guys would spring for Walt's reasonably-priced books, you'd have the answer to this, and a lot of other things.0
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I have also heard about placing wooden cloths pins on the line between the pump and carb. Anyone try that one yet?0
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I've been interested in the vapor lock issue for some time. Obviously, having your system set up properly is key, and Walt's books are great guides. That said,contributing factors to the problem are altitude and gasoline volatility. Gas, alcohol and everything else evaporates faster at higher altitudes. (Less air pressure on the surface of the liquid) Add ambient heat, and problems arise. I live at 7,000 feet. Norm Blackmer rebuilt my '40 carb with high-altitude jets. (Since there's a minimum of vacuum to move the vacuum advance, the timing is advanced considerably, too.) Members coming east on I40 will be running at 4,000 feet + from Flagstaff through Oklahoma, cresting at 7,000 or so a couple of times, notably when climbing out of Albuquerque to Santa Rosa. Of course modern fuel-injected cars and trucks have computers that make the necessary adjustments.
As for volatility, today's gas is much more volatile than it used to be, so it evaporates faster. Thus the suggestion to add diesel or Marvel Mystery oil, which makes the gas less volatile.
However, if it's high and hot when you pull over for a pit stop and your baby won't start, open the hood and go back for another coffee. Things will cool down, and she'll go. :cheer:0 -
Uncle Josh, they listen to to many people and never get the correct answer. I drive my Hudson on route 40 and up to 12,000 feet and never have a hot start problem, my carbs are 968s, and with the standard 75-834 metering rods Any one that sets their car up like I tell them, my rebuilt carburetor, and my fuel return system, will never have vapor lock. Must also get rid of that Hudson fuel pump if you intend to drive on long trips. My thermostat block off plate kit also helps as it keeps the engine a little cooler. My modern oil filter kit also helps as it cools the oil also a few degrees. 11 trips across this country in June, July and August and have never had any vapor lock problems. I'm going to OK, and if anyone wants to take a run with me, on a hot day to higher levels, I'm ready. Walt Mordenti0
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I was wondering, does a insulation pad under the hood(bonnet) reduce the engine compartment temp enough to warrant the cost and labor. Has anyone tried this? PS, I started adding qt of kerosene to a tank full, Juries out at this time. I was thinking about that fan idea. Cutting a hole in the right side radiator grille deflector baffle to allow air to pass, aimed right at the cabs. A small fan might be placed there. The engine compartment, on the step downs, is like a pressure cooker. The only air circulating is drawn in through the hot radiator and the sun beating down only adds to the grief. Anyway, any thoughts?0
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Ron, I once debated taking a small bilge ventilator designed for bass boats or some inboard ski boats, and cutting a hole like you said then put the fan in there to blow cooler air onto the carb. Instead I cut the steel line from the outlet side of the fuel pump about 5 inches up then loosened the fitting nut and turned the tube towards the fenderwell and ran a new rubber line to a small fuel filter and from the filter over to the carb. I have had no problem with vapor lock since doing this. I have a 2bl(NOT TWIN-H) I don't know if that makes a difference or not. If I were able to do it I would probably use Walt's system. But for now this works for me.
I have to say that the tallest mountains around here are the Great Smoky Mountains. Which some say are but warts on the Rockies.
Bob Hickson0 -
Ron, I once debated taking a small bilge ventilator designed for bass boats or some inboard ski boats, and cutting a hole like you said then put the fan in there to blow cooler air onto the carb. Instead I cut the steel line from the outlet side of the fuel pump about 5 inches up then loosened the fitting nut and turned the tube towards the fenderwell and ran a new rubber line to a small fuel filter and from the filter over to the carb. I have had no problem with vapor lock since doing this. I have a 2bl(NOT TWIN-H) I don't know if that makes a difference or not. If I were able to do it I would probably use Walt's system. But for now this works for me.
I have to say that the tallest mountains around here are the Great Smoky Mountains. Which some say are but warts on the Rockies.
The insulation is more there to protect the paint on the hood than to protect against vapor lock.
Bob Hickson0 -
I have to go with Walt on this one. Never had a problem with my stepdowns and as I read through Walt's books and Tech Tips it is easy to understand why. I found that most of what Walt did (He did have a few tricks that I have learned in speaking to him in the past few years.) was pretty much what I did over the years.
When I set up the "Salt Flats Racer" I went the extra mile and opened up all the water jacket ports when we boiled out the engine. The temperature on the Salt Flats is normally above 110 and often around 120. After you make a run you pull into the inspection tent and pop the hood and shut down the engine. Often they take a quick look and let you go. If your car does not start they push you away for the next car. I added a electric fuel pump that would permit me to adjust the fuel pressure so I could be sure that with the lighter viscosity gas of today I would not have any problems with vapor lock. I would set the gage to 11 psi before each run and ever have had a problem.0 -
Brownie,did you say your fuel pressure is 11 psi? I believe Hudson calls for 3 1/2 - 4 1/2 on the twin h carbs. I tried Walts feedback system a couple of years ago. Still fuel starved, albeit, it took longer. Solved problem, at least this year, with a direct electric pump and lost the mechanical one. Hey, where did you guys mount a rotary vane pump on a stepdown? Park has one on his 47, any on stepdowns?0
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Did you mount the restricter in the return line, using a 30 or 40 thousand hole? Without this part you are starving the engine as fuel is going back to the tank faster than to the carbs. I run 4 1/2 lbs of pressure and have never had a problem. Walt0
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RonS wrote:Brownie,did you say your fuel pressure is 11 psi? I believe Hudson calls for 3 1/2 - 4 1/2 on the twin h carbs. I tried Walts feedback system a couple of years ago. Still fuel starved, albeit, it took longer. Solved problem, at least this year, with a direct electric pump and lost the mechanical one. Hey, where did you guys mount a rotary vane pump on a stepdown? Park has one on his 47, any on stepdowns?
For normal driving I would run it at 5 psi. When I went to the Salt Flats to race I would move it up. If I ran at the 5 psi it would cut out when I hit 90. And, when I stopped at the inspection area the engine was hot (around 210/220) and the day was around 120 on the salt. I continued moving it up 2 psi after each run. When I hit 9 psi it quit cutting out but I could only get it to 115 mph. I moved it up to 11 to hit my top speed of 129 mph. My average for the day was two runs at 122.683. I called it quits. I sold the car last year and took the pressure boost gage off the car when I sold it.0 -
You asked if anyone used a vane pump on a Hudson .I used one for some time on my 51 Super 6 with good results. Following instructions included in box I mounted it low in engine compartment. Basicly across from factory fuel pump on the inner fender just above the frame,
Roger0 -
RonS wrote:Brownie,did you say your fuel pressure is 11 psi? I believe Hudson calls for 3 1/2 - 4 1/2 on the twin h carbs. I tried Walts feedback system a couple of years ago. Still fuel starved, albeit, it took longer. Solved problem, at least this year, with a direct electric pump and lost the mechanical one. Hey, where did you guys mount a rotary vane pump on a stepdown? Park has one on his 47, any on stepdowns?
I have a Carter P4070 rotary vane pump mounted inside the rear unit body in line with the fuel line. The pump is preceded by a fuel filter. The pump is bypassed as Park W has done with his 47 and I am able to operate all the time or at will via a relay and on and off switch. This pump is currently operating through a Hudson dual action fuel pump. At times in the past I have bypassed the mechanical and used the electric alone.
Previous to converting this Hudson Stepdown to 12 volts an identical 6 volt pump was mounted in the same location. The output line from the Hudson pump is connected to a second fuel filter and followed by an adjustable fuel pressure regulator.
This fuel system has fed several carbureted intakes, stock Hudson 2BBL, Chrysler carburetor on the Hudson 2BBL manifold, Hudson Twin H and a Clifford intake running a Holly 500.
The car is street driven and is also equipped with a Dodge B400 van radiator and an AC system.
The fuel system has not failed to delivery appropriate performance and to date no vapor lock experiences. The ambient temps in my area range from freezing to 100+ degrees. Our local fuel has been a 10% minimum ethanol blend for at least 8 years. When I fill up I generally add enough diesel to get a 20-1 mix ratio.0 -
Hudson added a functional hood scoop in '54 to "ventilate" the engine, maybe they were aware of a vaporizing issue. Anyway, the above interesting discussion is why early on (after much research) I decided to:
go to 12 V
reduction gear starter
install electric fuel pump (at tank)
high flow electric fan
remote oil filter with cooler
'56 engine (improved cooling)0 -
Doug, what type of pump are you using? Wild W, where exactly is the R vane pump mounted. I am using a solenoid type alone, mounted at the tank, straight into the carbs with a pressure regulator in between( 4PSI). I like the rotary better, but could not find a good place to mount it close to the tank and out of sight of nosey judges. Also in some spots the terminals were lower than the frame.0
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dougson wrote:Hudson added a functional hood scoop in '54 to "ventilate" the engine, maybe they were aware of a vaporizing issue. Anyway, the above interesting discussion is why early on (after much research) I decided to:
go to 12 V
reduction gear starter
install electric fuel pump (at tank)
high flow electric fan
remote oil filter with cooler
'56 engine (improved cooling)
Not to derail the thread... But what starter are you using, or is a custom job?
Thanks.0 -
Ron S asked: Wild W, where exactly is the R vane pump mounted?
The fuel pump is attached to the inside right frame structure on which the gas line traverses. The bracket provide with the pump was used to mount it. The pump is large and if one stoops down the bottom of the pump would be visible. My installation includes a thick rubber shield to prevent road debris damage, so the pump is not visible except from below.
I suppose one could fabricate a mounting system that mounts the pump nearer to the fuel tank. For me the current location provides the service I need.
My car is a driver and I do not participate in judging events.0 -
Sorry for the delay. The pump is a standard over-the-counter auto store Facet-Purolator solid state "interupter" style that assures no vaporizing. Very quiet when pumping. I tried a rotary pump on another car and it made a racket. The starter is a Mopar style reduction-gear that will be mounted on the Wilkap transmission adapter I purchased.
http://www.facet-purolator.com/index.php?option=com_content&task=category§ionid=7&id=14&Itemid=360 -
Ski4 had an interesting thought. I checked out the stack of gaskets on the Twin H carbs, I have 5 below the shield( between the shield and manifold) and one above it ( between the carb & shield). Any thoughts if this is OK? The book says 4 & 4, someone said 5 and 5.
Walt, sorry,regarding the feedback system, the restrictor was 030 as you stated. Only change that I made was that I substituted a T fitting instead of the Chrysler fuel filter, since I have a AC glass bowl filter in the near location and it would look weird.0
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