Vapor Lock

[OUTFXD]

So.  Had a Doctors appointment in the next city over.  about 45 miles.  I figured this was a chance for Jacquiline to dazzle me with her reliable ride and longevity!

 

Boy was I wrong.

 

Mistake one.  I wanted to avoid the local freeway so I asked Google Maps to find me the fastest route avoiding freeways.

 

On this glorious 85 degree day,  the google algorythim chose what had to be the most convoluted path of slow speed, heavy curve, Steep hilled, four lane heat soaked hiway with a stop light every 100 meters with the highest statistical probability of catching a red light in the world.

 

Seriously I must have hit 3/4 of them! And this meant hot hot hot engine bay.

 

It got to the point where I could barely pull out when the light changed. Totally felt like fuel starvation.   a couple of hard starts after she stalled.  Finally stalled out on a hill on  what had to be the most popular road in the country, so as I sat there in my broken down Vintage car with the hood up, every judgemental looky Lou in the word drove by.

 

I popped the hood and sure enough the Fuel filter was about 1/5 full.  and on top of that I could see the gas Boiling.  Nothing I could do but sit there suffering the gazes of fools until the engine cooled down.

 

I pulled the fuel lines as far away from the exhaust as possible (and yes they where HOT).  and taped a pop can to the fuel filter as a make shift heat shield.

 

Did it work?  Meh.  I was able to eventually limp my way home with only a couple stalls and occasional engine/fuel starvation.

 

So.  Is this hereditary to our cars and what is the best way of dealing with it? 

 

I was thinking a couple of those heat sleaves motorcycle sport enthusiasts enjoy putting on their spark plugs. an actual heat shield for the fuel filter. 

 

Havent decided on a heatshield/spacer plate for under the carb.

 

Thoughts? Ideas? Advice?

[Bryan G]

I blame newer gasoline formulations more than I blame our cars. I have a feeling this wasn't very common when they were younger. The most common remedy is an aux. electric pump, and that's the crutch I lean on. You could also add something to the gas to try and lower the boiling point. On one car I found that a gallon of kerosene or diesel, added with each fill up, made a real difference. 

[Worden18]

I use a finned aluminum shield under the carb.  Wrapping the lines should help, too.  Yep, electric fuel pump as well, although I haven't made it that far on my car.  

[Dan Hiebert]

The companies that cater mostly to racers, (Summit, Jegs, ETC.), sell various methods of insulation for fuel lines.  A couple of our local auto parts houses up here sell it too, but with limited options.  I'm with BryanG, ethanol improves the vaporization of gasoline, which means it also improves the potential for vapor lock.  Finding straight gas, and/or anything that keeps the fuel system cooler will help.  Electric fuel pumps help immensely. 

[Kilgore47]

The fuel line from the pump to the carb on the P15 has been re routed away from the exhaust manifold.  No more vapor lock.  And you should consider changing that plastic fuel filter for a metal one.  The plastic one can melt and leak.

[Sam Buchanan]

You can see the fuel line on my P15 running across the firewall a long way from the exhaust manifold. Since I run a full-time electric pump at the tank the fuel line can run directly to the carb. By the way, the little red-topped gadget is the inertia shut-off switch for the electric pump.

 

 

[plymouthcranbrook]

I agree that the major issue is fuel volatility. My 52 has a modern EMPI carb mounted on a pedestal adapter and still on a very hot day(90+) I occasionally have a situation where the fuel in the carb boils over into the manifold and makes a restart after a short wait a bit harder with a over rich response when it starts.

[kencombs]

I Plan to run water instead of exhaust through my intake.   Mainly because my grinding to taper my two barrel adapter hit the exhaust passage, oops!  So I filled it with epoxy and will place a thin stainless plate between the manifolds.  When I split the manifold for duals it will get blocked there also.  Then run water be routed in and out of that chamber.  So the manifold temp under the carb should be much cooler than it would be with exhaust access to that area. 

 

I think I'll also adapt the fuel routing pictured above as I plan to install the 2bbl carb with the fuel inlet in the back anyway for throttle lever clearance.

 

And, electric pump too, near the tank with an inertia switch. 

 

Hopefully that will get a lack of both starvation when running and perculation when shut off.

[plymouthcranbrook]

2 minutes ago, kencombs said:

I Plan to run water instead of exhaust through my intake.   Mainly because my grinding to taper my two barrel adapter hit the exhaust passage, oops!  So I filled it with epoxy and will place a thin stainless plate between the manifolds.  When I split the manifold for duals it will get blocked there also.  Then run water be routed in and out of that chamber.  So the manifold temp under the carb should be much cooler than it would be with exhaust access to that area. 

 

I think I'll also adapt the fuel routing pictured above as I plan to install the 2bbl carb with the fuel inlet in the back anyway for throttle lever clearance.

 

And, electric pump too, near the tank with an inertia switch. 

 

Hopefully that will get a lack of both starvation when running and perculation when shut off.

I kept mine with exhaust heat as my manifold is in good condition. I did see the adapter that Langdons has for use with the headers they sell.  I don’t really drive my car after it gets beyond modesty cold so I have no problems. I will be interested in seeing how your setup works

[keithb7]

The firm quick long term fix is indeed an electric fuel pump. Also a possible pressure regulator if needed. The longer I am here, I can see that @Sam Buchananhas been around the block a few times.  I see some modern comforts in the one photo he posted above. I count 6 things that ain't what I find under the hood of my old Mopars. How many do you see?

Edited August 18, 2022 by keithb7

[Booger]

1 minute ago, keithb7 said:

The firm quick long term fix is indeed an electric fuel pump. Also a possible pressure regulator if needed. The longer I am here, I can see that @Sam Buchananhas been around the block a few times.  I see modern comforts in the one photo he posted above. I count 6 things that ain't what I find under the hood of my old Moopars. How many do you see?

Well a wise ol codger, Sam. Yeah VL is a real thing on a hot day. Lots of thing-a-majiggs and do- hickeys under that hood. get too many add-ons you forget what they do.

now that these cars are getting alot older right along with us, they tend to need more attention. When I was a lad I beat the ever loving dog snot out of my Plymouths

[Los_Control]

Different ways to cure VL.  ..... First thing is to acknowledge the modern fuel will percolate faster then older fuel .... something to live with.

 

The fuel will be pumped from the fuel pump to the carburetor.

If we are in town, driving slow. The float bowl will shut off the fuel to the carburetor.  Then when you park & shut the engine off .... the fuel evaporates turns to vapor.

 

The key is too add a T before the Carburetor. Run the line back to the fuel tank.  The carb is fed with fuel, any extra is routed back to the tank & always a constant supply of fresh cool fuel to the carb.

 

Simply how modern cars fixed the issue.

A quick fix to add a electric pump is a good get me by.

Adding a return line to the tank to actually cool the fuel, prevent the problem in the first place ..... your choice.

 

 

[Sam Buchanan]

1 hour ago, keithb7 said:

The firm quick long term fix is indeed an electric fuel pump. Also a possible pressure regulator if needed. The longer I am here, I can see that @Sam Buchananhas been around the block a few times.  I see some modern comforts in the one photo he posted above. I count 6 things that ain't what I find under the hood of my old Mopars. How many do you see?

 

Thanks, Keith. Yep, the purists probably look askew at some of the mods I have in the wonderful old '48 Plymouth.

 

But the changes haven't been made just for the sake of change. I've carefully evaluated common trouble areas of these old cars and addressed them. I love driving this car a lot, often 30+ miles at a time--it has make the 25 mile trip to the airplane hangar so many times the airport lizards want to know where it is if I show up in something else. I expect it to start...every time...in all conditions, stay running...in all conditions....and keep me in the driver's seat instead of crawling under it during an excursion. I haven't eliminated all the weak areas, but most of the common ones. Spending a little extra money is worth it to me to have a reliable old car.

 

I come from the custom-built aviation community. If an aircraft I have built has a shortcoming, I can't ignore it and use the aviation laugh line. "Oh, it'll probably be ok". The item in question gets a long-term fix for good reliability. So my P15 has an alternator which eliminates the often trouble-prone genny/regulator, a dual-chamber master cylinder for added safety margin, disc brakes, a spin-on bypass oil filter, a paper element inside the original filter housing, an electric fuel pump which eliminates the issues discussed in this thread and its associated inertia safety switch. I've added turn signals, and rewired the car where necessary. As long as the trip doesn't require more than 60mph, I'll drive it anywhere (except in rain, still have vacuum wipers and bias-ply tires!).

 

This has not made the car more complex, in many cases it is now less complex and far more reliable. I've never had anyone criticize the mods, most are complimentary and appreciate the rationale. And in no way has the intrinsic charm of this old Mopar been compromised. But if someone wants to keep their car "original", I'm ok with that. 

 

 

Edited August 19, 2022 by Sam Buchanan

[Booger]

shes a Beauty!

[OUTFXD]

17 hours ago, Sam Buchanan said:

 

Yep, the purists probably look askew at some of the mods I have in the wonderful old '48 Plymouth.

 

But the changes haven't been made just for the sake of change.

I hear you.  My car isnt and will never be a concourse restoration.   I settled that debt when I bought her.

 

I am making her look as original as possible and dont plan on swapping out the flathead engine or the non-synchronized 1st gear transmition.   And hope/want her to retain the spirit of a vintage automobile

 

However I can see where there have been technological advances that she will benefit from,  that wont detract from her spirit.

 

Disk Brakes and seatbelts are in her future.   As are a 12v alternator, full LEDs, Mopar Electronic ignition (from the 70s), a solid state Voltage regulator, and an electric fan.  I am considering milling the head for improved compression.

 

Now I know that there are purists out there that will not approve of my modifications.  But as a disabled bloke with limited skills/finances. It was never going to happen anyways and is worlds ahead of the plan the kids I took her away from had.  Sand blasting the paint and Using salt and peroxide to intentionally cause her to rust. 

 

But in my opinion I am making small improvements,  that can be reversed at a later date with minimal work.

 

I am individualizing MY car to best suit how I want her to be. And  I feel that my intended modifications will improve her for the way that I intend to use her. 

 

She will not live in my garage to be brought out to be washed or taken to a show.   I intend to drive her on the regular,  and need her to be suitable to my life style.

While retaining the spirit of a vintage car.

 

Edited August 19, 2022 by OUTFXD

[Sniper]

Mine will be a sort of vintage hotrod.  I could rip out the flathead and slap in a V8, in fact I passed on a Magnum wagon that would have been a good donor.  Front and rear IRS, Hemi V8, automajic trans, etc.

 

Passed because that's not what I wan to do.  Yes I converted to 12v, put in LED headlights so I can actually see at night, put in discs so I can stop.  Yes I know the drums work, for values of work, but I drive it hard.  Updated the front suspension, mostly a rebuild, with cut Aerostar springs and good gas shocks.  The reasr will get good gas charged shocks and we will see how that affects the wheel hop.  Engine, upsizing to a 230, with a high compression aluminum head, dual 1bbl TBI, maybe a cam, split exhaust. 

 

The rest of the car, plan to add AC, otherwise keeping it stock.  But if I can figure a way to put more modern self energizing rear drums on I will.

[JBNeal]

additional information - flathead hot-starting improvements