Vapor Lock

[SierraJoe]

Another post about vapor lock. I fixed the overheating problems, but I?m still held hostage by vapor lock. I was only able to go out once last year because of the fires in the Tahoe area where I live, but the one time I did get out vapor lock struck again. My Clipper has the Dodge 440, dual headers, and a fairly new Elderbrock Performer Q-Jet Carburetor (model 1905). The Clipper runs fine, but the campground I like is off a steep climb up in the mountains. If the engine is running around 210 degrees on a hot day in the mid 90s and I slow down the engine rpm such as to pull into the camping area, the Clipper will die and not start again till I let it cool down and spray starting fuel into the carb as pumping the gas pedal will not get gas to the carb.  I know this was probably a problem in the past with my Clipper as there are several cans of starter fluid in the cabinet. The carburetor already has a composition spacer block installed between the carb and the engine cylinder head. I am going to add a new mechanical fuel pump and install an electric fuel pump next to the gas tank that will have a switch in the cab to flip on when needed. I am ordering the parts to install and hope to get out later in the month once the snow is gone.  If this works, great, if not I going to try adding a hood scoop like Clipper Joe recommended to get more air into the engine compartment.

[Toedtoes]

Yeah, the 440s are just too big for the engine space to be able to cool down easily.  As most folks better insulate the doghouse so they don't get burned, that will also prevent the engine heat from dispersing.

I'll ask Clipper Joe to check this thread and offer more guidance for you.

[Clipper Joe]

Hello SierraJoe,
Glad To Hear From You Again,
Thanks To Toedtoes She Emailed Me About Your Problem.
It Took Me Many Years And A Lot Of Trying,
To Stop The Heating & Vapor Lock Problems.
What Is Vapor Lock, Is We?re the Gas Turns Into A
Vapor. It Is Over Heating.
That Is Why Dodge Went To The Thermoquad
Carb, It Has A Special Plastic Float bowel.
Also, I Found That The Fuel Filter Is On Frame, Under Passenger Door.
I Found It Wound Ge So Hot That It Was Also Close To The Exhaust Pipe.

What I Did To Solve That, Filter Getting Hot.
1.) Installed New Metal Wix Fuel Filter.
2.) Insulated Around Fuel Filter With Wall Installation.
3.) Made A  Galvanize   Cover And Add 2? Solid Installation & Glued to Cover Shield,
Screwed To Frame. This Really Helped.

I Did Install A Hood Scoop & 2 Ea.6? Diameter Holes/ With Screens On Hood.
I Think I Still Have A Template For Scoop, I Got Online. Note: Had to Modify To Fit Dodge Hood. 

One Last Thing Joe, I Had That Problem When I Had The After Market Carb, Eldebrock  Carb,
Go To OEM Carb,
I Still Have A Few Carbs & Ca SmogApproved Carb  Eldebrock . At Home, Have Sold My Clipper.


One Thing My Diesel Pusher Monaco Does Not Vapor Lock, Cummins
Motor.

Hope This Helps You,
Clipper Joe

[SierraJoe]

Hi Clipper Joe, nice to hear from you again. I've heard the same thing about these carbs being prone to vapor lock. I'm hoping to keep the carb as my Clipper runs smoothly with no issues and idles like a purring kitten. I never thought about the fuel filter, I'll implement your suggestion. I have aftermarket headers on my Clipper that might be adding to the problem of heating up the filter. I don't remember how close they are to the filter. From what I have read, an electric fuel pump can make a huge difference. I decided to replace the mechanical filter verses remove it when I add the electric fuel pump. I'll add a switch to the electric fuel pump inside the cab that I can flip on when climbing grades or to pump gas to the carburetor when the Clipper has sat a long time. The 440 is such a big engine to be in such a tight configuration. My brother has a 1970 Dodge Challenger with the same engine and when you open the hood you realize how big the engine really is. Thanks again for you help!

[Clipper Joe]

Hi Joe,
Remember, If The Electric Pump Has To Meter Fuel To Carb.
So You Have To Have A Gas Flow Meter, Remember The While Switch Is On,
Fuel Is Still Flowing, Chance Of Engine Fires.

Have You Thought Of Using Header Wrap On Passenger Lower Header.
That Helps.
My Ex Father In Law Had A Class A He Added A Electric Fuel Pump, Have To Work Out Right Fuel PSI
And Proper Regulator.
You Get Right Fuel Ratio, It Should Work For You.

Just Get The Heat Out Of Engine Bay Area, I Found That My Hood Scoop Did A Good Job,
Also Flip Your Air Cleaner Cover Over To Allow More Air Flo Into Carb.
Try That.

Good Luck,
Clipper Joe

[SierraJoe]

Hi Joe,

The electric fuel pump I plan to install is the Carter P4594 which puts out 6-8 PSI and 50 GPH. My Elderbrock carburetor is rated around 6.5 PSI and from what I have read, the Carter being a low pressure pump will not require a fuel regulator. I was on the fence about replacing the mechanical fuel pump and just sealing it off with a metal plate but decided against it. The new manual fuel pump will be rated at 6 PSI and 29 GPH. I'm replacing it also because it's 45 years old and I bet the rubber membrane inside is shot. I don't want a leak to put gas into the crankcase. I'm with you and an engine fire is always a real concern of mine. I've already replaced all of the rubber fuel lines and will hook the electric fuel pump on/off switch to the ignition so that I don't accidentally leave it on. I was thinking about what was different about the last time I had vapor lock. I camped about 3/4 way up the mountain grade verses crossing over the summit into the 7000 foot valley. When I camped in the valley, no vapor lock on the drive as the engine cooled off while I was driving in the valley to my spot. In the time I drove about 20 miles from my house, the outside air temperature dropped from 95 degrees to around 75 degrees. Last trip when I pulled off the pass to camp instead of crossing over to the higher valley. When I stopped to back into my spot, The engine died and would not start again. It was still much cooler, but the engine didn't have time to cool off like it would if I crossed over into the higher valley. I tried a half hour later to start the Clipper but couldn't get gas to pump into the carburetor. I had to pull the air cleaner and spray starter fluid into the carb to get it to start and pull gas from the tank. I'm thinking vapor lock is occuring either in the fuel filter or the manual fuel pump or perhaps even both. As you can see from the photo and your own experience, the fuel filter is tucked into a confined space where heat probably builds up pretty quicky without any air flow. I'm betting on the fuel filter being the main culprit. I will take your advice and insulate the filter. Today it's 34 degrees and snowing at my house. 20 miles away at my camping spot it is also snowing and 20 degrees. Monday and Tuesday it's suppose to get down to around 11 degrees. I can't remember May ever getting temperatures this low around here. On the bright side it's suppose to be around 85 degrees next weekend. Thanks again for your advice!

[SierraJoe]

I'm was just looking at Fiberglass Wrap Shield Sleeve on Amazon and it is suppose to reduce heat by 60%. I think I will use this for my fuel lines. I'll encase the fuel line from the mechanical fuel pump to the carburetor. I probably should also encase the line from the fuel filter to the input of the fuel pump also. The sleeve might also be good for the spark plug wires. I had one of the wires melt in the past when the engine was running too hot.

[Clipper Joe]

SierraJoe,
I Got My Heat Res. Tape From Autozone,
Anything You Do To Keep Heat Away, Is A Plus.
I Also Used Header Wrap On My Exhaust Pipes.
I Got 8mm High Temp Silicone Wires, And Put High Temp.
Covers On Them Also.
Dodge 440 CI Put Out A Lot Of Heat. Some Clipper Owners, Installed Ram Air
Piping From Under Front Bumper, And Try
To Bring Cooler Air To Air Cleaner Intake.
I Really Like My Air Scoop On Hood, I Also Put In Under Carpet, Dynamat Sound Deading,
I Also Redone The Doghouse, Do Not Put Duct Tape In Doghouse,
Use Fire Proof Of 500+ Degrees Rated Material & Tape/Glue.
Should Be Photos Or Posts On Forum  Or YouTube.
Good Luck, Let Us Know How You Make Out.
Post Results..
Clipper Joe

[rvguy101]

thing is you got to keep the fuel from getting hot, i don't own a clipper anymore. but i went with efi on my other dodge, amc 727 with a lockup converter. but i added new steel flex line with heat Wrap. & added the fuel Filter next to the pump. as it efi, it have a electric fuel pump. a electric fuel pump will pump more fuel fasted as well. i would Header Wrap the lines, & move the filter away from heat.  i also would add the pump away from heat to. add it any where from heat.