My dads 78 F-350 used to vapor lock all the time, we added an electric fuel pump and solved the problem. I think that my 57 272 is doing the thing but I am a diesel mech. and no very little about these carborated engines. If I drive it very far or let it get very hot I can't restart it. I am thinking that it might be flooding also but don't know. It is backfiring a little under hard acceleration but I don't know if this is causing the problem or not. Any help would be appreciated because the engine is missing the injection pump and injectors(the fuel system that I understand)

Thank you,

Ben

 

No ideas?????????????

Ben

 

Backfiring under hard acceleration is usually indicative of a lean mixture, especially when engine is cold. Delayed hot starting is caused by fuel boiling or vaporizing in the fuel line between pump and carb. fuel expands when heated and forces its way past the needle and seat in the carb and causes flooding. try insulating the line between carb and pump.

 

Ben,

I've been having the almost identical problem with my C-600 (HD 272). My truck pops under heavy acceleration but usually dies. It will immediatly restart, but usually die again when you accelerate it. It does this 'thing' after about 5-10 miles. I have done it all from removing and cleaning the tank, replacing all lines, and fuel filter. I bought the truck in NC about 4 months ago. The guy had replaced the fuel pump the day I picked it up, so why check it? Wrong. Frustrated to the limit today, I pulled the pump to check it out.... it was the WRONG pump!! I happened to have a new one in the box hiding on a shelf in the shop. Slapped it on and like magic, problem solved.
This may sound stupid, but have you checked the timing? Light duty 272 I believe is set at 8 degrees Before TDC, heavy duty at 10 degrees before TDC. Unhook your vacuum advance from the dist. to time it. Then rehook and check time at idle then rev up to make sure the mark moves (know that your advance is working).

Good luck,

Randy King
Check out my page at msnusers.com/1956fordtrucks
I am into the heavy trucks...see them on my page
2003 F350 crew powerstroke auto srw
1956 F-100 (2)
1956 F-350 flatbed 272
1956 F-500 223/6
1956 F-600 272 5/2
1956 C-600 HD 272 4/2
1970 F-100 Sport Custom Street Rod
1953 F-350 flatbed

and still looking!!

 

I thought backfiring under a load was rich??? Anyway I drove it to my engine class last night and found a few things. The biggest ouch was a rotten rubber hose leaving the filter, found a few chunks at end of line that were to big to fit through the fitting(lots of little pieces plugging up the insides I'm sure). The fuel pump is new and builds some good pressure. I had the carb rebuilt and the timing set by a guy in town who does nothing but tune engines(everything from a honda to the alcohol racers) and is very good. I don't think it is vapor locking, I think there is just fuel leaking past the needles and flooding it. I should have it worked out next Tuesday during class.

Thanks for the help,

Ben

 

Ben,

If you determine that it is vapor lock, a simple way to correct it is to place an inline fuel filter in the line just before it goes into the carburetor. This has worked for me in every car I've ever owned where I experienced vapor lock. The filter serves as a cooler for the fuel as it enters the carburetor. Also, if the line going from the carburetor is metal, change it to a neoprene fuel line. This will also cool the fuel and prevent vapor lock in most instances.

 

Someone was talking about the timing of the engine and I would like to suggest that you check the condition of the points in the distributor. With that type of system the engine can back fire under acceleration too when the points are burnt. I have learned over the years to get points that have the copper strip installed with the spring for the free side of the points. The current flowing through the points can cause the spring to weaken and then points will bounce. Good luck.

Gear Up

 

All very good points I had the same problem, not only with my 1960 F100 w/292 all stock, but with my sons old mustang with the 302 in it. It would die going down the hwy. Say I would drive 30 miles and park for a half hour and drive home the engine would die and we would swear that it was vapor lock.

The problem is with the points, I called my buddy up who is my engine guru.. and he and I went out for a spin to test it. Everything was fine until we went to park it, and it starting dying out. He opened the hood, removed the distributor cap and put some dielectric lubricant on the distributor shaft where the points meet the lobe, and solved the problem instantly. I was shocked and dumbfounded. I hate him

Keep em adjusted and lubbed!

 

I have only ran the truck for a few minutes here and there since that post. Two wheel drive dually in 1 foot plus snow doesn't work well. I installed new points a year ago but I will try lubing them. Thanks for the tip.

Ben

 

Hey Ben,
If you are out there bucking snow don't forget that the distributor is in the front of the engine and the snow coming up though the various openings meet the dist. cap first. You may be having problems with getting moisture in the cap itself and that will the engine to run poorly. The spark will the path of least resistance.

Gear up

 

The distributor on the Y-Block is in the rear. I havent drove it for two months because we have over a foot of snow. I think I have a few more months to get it figured out, from the looks of the weather.

Ben

 

From what you describe it sounds like the timing. That would cause it to backfire and not crank after the engine warms up. Check the points. A set will burn up quick if the switch was left on. Be sure to really check your tank, filter and lines again. My truck had a dirty tank and did close to what your truck is doing. It let the fuel filter fill up but would not flow enough fuel to run for any length of time. It ran long enough to get me a mile or so away from my home then nothing. I changed tanks and that fixed it.

 

If it is the dreaded heat related vapor lock, I second the in line filter helping plenty.

I might suggest too that a good insulating spacer under the carb keeps that manifold heat from conducting up to the carb. That cured even this SC heat vapor lock

 

Gentlemen your fuel problem may also be do to the viberation of your fuel lines someplace or most of the place. Double the line fastners coming from the tank they may be spaced to far apart. Also the line from the frame to the fuel pump. If you think that line could be the problem put a loop in it. This may or may not be the problem but what will it hurt. If it is vibration or vapor loc the loop will help both. This is an old remedy from the 1950s it worked then why wouldn't it work now. We had to do it with the mechanical oil preasure guages to get an accurate reading of oil preasure on our race cars. I have used it on several gas lines and most of the time it worked including with lawn mower engines which vapor loc at the blink of an eye. Hope this makes sense to you.

POKY