Help with Flathead vapor lock

[Tim Berry]

Here is a problem. How do I prevent vapor lock in the old cmp without fitting an electric pump. The vapor lock is very bad and the V8 at times simply stops.

Lately in my area it has been 40 degrees C. Any ideas.
Tim

[Jordan Baker]

Tim I posted my reply in the softskin forum. It involed Alex Blair and Geoff and some hissing and lots of steam.

[Col Tigwell]

Have you tried lagging the pipes with some non asbestos type tape.

We used to have this problem and it gave relief. Also you can then pour water on it too, which helps even more.

Regards

Col Tigwell
Downunder

[Tony Smith]

Try to source AVGAS. It has a lot lower amount of volatile additives and is less suceptible to vapour lock.

[Phil Waterman]

Vapor lock or flooding take your choice, but electric fuel pump with an isolation switch is the answer. Hot Rod Lincolns and Fords have run in my family as long as I can remember. I suspect that at times what is blamed as vapor lock is actually a combination of boiling the fuel in the fuel line and flooding the engine because the fuel boiling pushes excess fuel from the carburetor into the engine as soon as you shut of the engine. My first car was a 49 Lincoln which had been extensively modified, it had been by dad’s, it didn’t like the hot southern weather and the fix had been to replace the mechanical fuel pump with a electric fuel pump mounted back at the tank. It also had an under dash switch to turn off the fuel pump (early antitheft device). I leaner early on that to start that 350 cubic inch high compression flathead V8 on a 6 volt battery you did want to crank it over for long. So starting procedure was to turn on the fuel switch and ignition wait for the pump to stop clicking, meaning fuel line and carburetor were full of fuel, then hit the starter button. Usually the reward was the nice rumble of the dual exhaust. If however it didn’t start and it was hot out then you turned the fuel pump switch off pushed the gas peddle to the floor held it there and hit the starter button again usually this resulted in the engine catching after a couple of turns.

When my brother started playing with flat head Ford V8s he found that they really did like to vapor lock or boil the fuel line he tried the same fix but didn’t completely cure the problem so he added a return line to fuel tank using small tubing. In this way the electric fuel pump back at the tank could purge the line of any vaporized gas in the fuel line.

There even use to be a little after market fuel pressure regulator and return line connection that went just before the inlet to the Stromberg Carbs it allowed you to run a higher pressure fuel pump with out flooding the engine particularly useful when fitting multiple carbs.

[Alex Blair (RIP)]

Phil....
That is a good point when you said....

When my brother started playing with flat head Ford V8s he found that they really did like to vapor lock or boil the fuel line he tried the same fix but didn’t completely cure the problem so he added a return line to fuel tank using small tubing. In this way the electric fuel pump back at the tank could purge the line of any vaporized gas in the fuel line.

Actually the small return line give the fuel a continuous path and the electric pump a continous load..
It must be sized that it won't starve the carburator under extream load ..It must be after the electric pump and before the carb....
With out that return line when your float needle is closed the electric fuel pump will dead head and eventually burn out the pump motor..

This was a problem on the forum a few years ago.and I mentioned that the addition of a return line would eliminate the burning out of the fuel pump..I think three pumps met their maker before a return line was installed..I think anyway..Memory plays tricks some times..

[Phil Waterman]

Originally posted by Alex Blair
Phil....
...
With out that return line when your float needle is closed the electric fuel pump will dead head and eventually burn out the pump motor..

This was a problem on the forum a few years ago.and I mentioned that the addition of a return line would eliminate the burning out of the fuel pump..I think three pumps met their maker before a return line was installed..I think anyway..Memory plays tricks some times..

Bendix had a shuttle (piston moved by mag field) came in both 6 and 12 volt was far better than the motor type it was design not to over preasure the float and yet could put out enough fuel flow to handle 350 cubic engine on big 4 barrel carb at full throttle. I'll go take a picture and try to find a source.

See http://www.mapleleafup.org/forums/sh...&threadid=5461

[Phil Waterman]

Found a source for inline 6-volt fuel pumps that have 4-6.5 psi fuel pressure. Go to http://www.macsautoparts.com/index.html and search part number EFP-9350-6

I've order parts from them in the past with success, they have a large number of parts for flat head V8s that might be of use to CMP owners.

Originally posted by Tim Berry
Here is a problem. How do I prevent vapor lock in the old cmp without fitting an electric pump. The vapor lock is very bad and the V8 at times simply stops.

Lately in my area it has been 40 degrees C. Any ideas.
Tim

Some very good suggestions already it seems.

I became heavily involved in these troubles with Dave's F15 Polsten and it is reported way back in previous posts.

Vapour locks occur on the inlet or suction side of the pump, whilst it was problematical when built, it is far worse now with high volatility fuel designed for injected engines; octane and volatility are not to be confused, AVGAS is high octane but low volatility to alleviate these situations and carb icing also. (see Reid Vapour Pressure)

The engine layout is ideal for substantially heating the fuel pump and the inlet fuel line, this starts the vapourisation process and the pump trying to draw fuel by creating a vacuum just lowers the boiling point further creating a vicious circle.

You will not get vapour in the output line as the pump pressure, provided it has liquid fuel supplied, increases the boiling point.

The original factory modification was a switchable (from the dash) electric pump (The Autopulse) located behind the battery at the back of the driver's step and effectively gravity fed. This kept some positive pressure to the mechanical pump inlet and was a standard fit to all these trucks being operated in hot/desert climates.

Dave and I decided to simplify the whole system for reliability after all the troubles you are having even in the cooler climate of the UK but probably with even more volatile, anti-pollution specified, EU standard fuel.

The mechanical pump has no push-rod fitted and the valves removed, the diaphragm remains just as a seal and the whole fuel supply is done by a 6V Facet pump located where the Autopulse would be. This cured all the fuel supply issues.

You'll still get the hot start difficulty as the carb is cooked by engine heat once stopped and simply percolates most of the fuel from the float bowl straight out of the main jets and quickly makes the engine totally flooded.

There is no absolute cure for this but four things can help a great deal.

Ditch the terrible Ford ignition coil and its ballast resistor (by just taking one wire to the other end) then use a modern 6V coil, the original can be left with dummy wiring for aesthetics.

Use decent modern, big name spark plugs, I think its NGK B6 for this engine. The B6M is common being a shortened insulator version for lawn mowers!

Ensure the battery is adequately rated and in good order; use the biggest cable possible with soldered lug connections from the battery to solenoid and then starter, don't forget the huge starting current has to flow back as well and the same size is needed from the engine back to the battery too. Standard 12V car size starter cable will not do. We saw an extra 1.25V at the starter by replacing these cables.

Employ a hot start technique, you know it will be flooded; open the throttle 1/3rd to 1/2, hold it there and crank it until it fires then slowly back the throttle keeping the revs up for a few seconds until its cleared itself.

R.

[Max Hedges]

With our F15a we still use the mechanical fuel pump, the glass bowl type, and with all the trips we have done the pump has worked fine. I will agree that an electric pump would be handy when it comes to starting the blitz after it has been sitting for a while.
When we bought our ford one toner it had an electric pump fitted and it used to flood the carby so we reinstalled the original pump, so now we use the electric pump only to start the old girl after its been sitting in the shed for a while. The old ute certainly has a lot more grunt than the blitz's you can nearly keep up with the rest of the traffic.
There is a lot of good advice in what the others have stated, we did have trouble once with a worn push rod so we just brased the end of it up and made it the right length again.
Mind you to ease the starting problem we also use 12 volt on most of the vehicles except the carrier.

Max

[Tim Berry]

From memory on my circuit breaker board the resistor has two wires attached. Do I simply disconnect these and join these together to bypass the resistor?

Thanks for the info on vapor lock

Tim

[rob love]

Originally posted by Tim Berry
Here is a problem. How do I prevent vapor lock in the old cmp without fitting an electric pump. The vapor lock is very bad and the V8 at times simply stops.

Lately in my area it has been 40 degrees C. Any ideas.
Tim

Move to Canada and your problem will be solved. -40 will then be your problem.

The old car club guys felt that since the vapor lock problems weren't realized nearly as much in the old days, there must be some part of the equasion that had changed. Their answer was it was the fuel that had changed fromulas, and was more prone to vapour lock on the old stuff. Many of us started mixing up to 15% kerosene with the gas, and much of the problem went away. The kero also was reputed to help lubricate the valves where the lead additives had been legislated away.
I had found that improvements in the ignition system actually did the most to assist the problems.
Many of us also installed the boat outboard motor primer pumps inline to the fuel pump to assist in the initial priming and to also reduce the back flow of the fuel to the tanks. Only costs about $8 and saved a lot of cranking with that poor 6 volt system.

[Lynn Eades]

Tim. Yes.
Phillip. 4 to 6.5 psi from your electric pump may be too high and blow petrol sraight through your neede valve. I dont have the specs here, but memory tells me that the mechanical pump delivers about 2.5 to 3 psi.
The delivery pressure of a mechanical pump is solely dictated by the SPRING.
Your fuel pipe shape/ location has a bearing on these problems
Neoprene tipped needle valves work well, if available.
Wear in the push rod etc results in fuel starvation due to loss of volume of fuel delivered.

Originally posted by rob love
Many of us started mixing up to 15% kerosene with the gas, and much of the problem went away. The kero also was reputed to help lubricate the valves where the lead additives had been legislated away.

Bit of a nomenclature/location problem here.

Kerosene could mean, AVJET, AVTUR or to me paraffin, the stuff for blowlamps, Primus stoves, Tilley lamps and parts washing owing to the cheapness and non-volatility.

If the latter, its effect as a valve lubricant may possibly be folklore but may be derived from the fact that it doesn't necessarily vapourise or get burnt. What it definitely does do is scour the oil from cylinder walls on intake and compression with accelerated ring and bore wear; the advice from the Chief Chemist at the Ass. Octel Co. in the UK is don't.

R.

[rob love]

Originally posted by FV623
Bit of a nomenclature/location problem here.

Kerosene could mean, AVJET, AVTUR or to me paraffin, the stuff for blowlamps, Primus stoves, Tilley lamps and parts washing owing to the cheapness and non-volatility.

If the latter, its effect as a valve lubricant may possibly be folklore but may be derived from the fact that it doesn't necessarily vapourise or get burnt. What it definitely does do is scour the oil from cylinder walls on intake and compression with accelerated ring and bore wear; the advice from the Chief Chemist at the Ass. Octel Co. in the UK is don't.

R.

We use white kerosene, which we use in things lke torpedo heaters. It is a cleaner version of diesel fuel. Not exactly cheap either, it was priced a bit higher than gasoline. I haven't bought any in a few years, but have to get a gallon today when I get to town to run the reddy heater.
FIrst I heard of the cylinder washing problem. We used to use a light grade of diesel while fogging the engine to preserve gasoline velicles for long term storage. Hard to believe the kerosene, which is a lighter grade of diesel, could cause problems.
We use the term Naptha on this side of the pond when talking about campstove fuel, and mineral spirits when talking about the solvent you use to was parts in. I guess we shoud pull out our NATO STANAG conversion charts and talk in mil-spec codes so we can all be in the same language.

Originally posted by rob love
We use white kerosene, which we use in things lke torpedo heaters. It is a cleaner version of diesel fuel. Not exactly cheap either, it was priced a bit higher than gasoline. I haven't bought any in a few years, but have to get a gallon today when I get to town to run the reddy heater.
FIrst I heard of the cylinder washing problem. We used to use a light grade of diesel while fogging the engine to preserve gasoline velicles for long term storage. Hard to believe the kerosene, which is a lighter grade of diesel, could cause problems.
We use the term Naptha on this side of the pond when talking about campstove fuel, and mineral spirits when talking about the solvent you use to was parts in. I guess we shoud pull out our NATO STANAG conversion charts and talk in mil-spec codes so we can all be in the same language.

Yup, we're where I thought we'd be!!!

You have many forms of "lamp oil" we don't have plus the Coleman fluid, white gasoline and stuff which we don't understand.

Diesel is certainly a good inhibitor and penetrating oil, red stuff is cheap too, but not on a par, certainly for cost (!) with Howe's Oil.

Our paraffin is much lighter than diesel, and a bit lighter than AVTUR, AVJET; these still have an oily characteristic which ("our") paraffin doesn't. It has their propensity of making a definite odour though which seems to permeate clothing and is difficult to be rid of and it does have a definite smell when used in a wicked lamp, heater or pre-heated pressure device.

The nearest I can get is this:
a group of high molecular weight alkane hydrocarbons with the general formula CnH2n+2, where n is greater than about 20. Its flash point is about 177ºC

When used for de-greasing parts it seems to remove the oil or grease and after blowing off with an airline there seems to be absolutely no lubricant or anything left, bearings washed in it that were previously apparently smooth with a hint of very light grade lube oil, become decidedly dry, gritty and slack. Its this ability to scour oil that makes it undesirable as a fuel additive unless wholly vapourised.

Surely someone here knows definitively what our domestic paraffin is to the rest of the world, or do I have to mail my tame fuel chemist!!

R.

[Richard Farrant]

Originally posted by FV623
Surely someone here knows definitively what our domestic paraffin is to the rest of the world,

R,

Domestic heating oil in the UK is known as 28 second and sometimes refered to as kerosene. There is now a premium grade available as well.

In NATO specs, what is known a 28 sec. Regular heating oil, is specified as NATO F-58 and British DEFSTAN as KERO/B Kerosene BS 2869 Class C2

Premium grade 28 sec heating oil is equivalent to DEFSTAN KERO/A , Kerosene BS 2869 Class C1. This one is not classified in NATO.

With the Blue Book (DEFSTAN), you will see the full spec.

Richard F.