I got some more bad news.

I have the original autolite 2100 carb freshly rebuilt about 2 months ago. The carb has always had a problem of boiling over. Whenever the engine gets hot it boils the gas out of the carb into the engine, emptying the carb and momentairily flooding the engine. The truck has had this problem for its whole life in colorado.
Now since gas is getting expensive ;$3.70 at the nearest gas station, so i dont run it very often. Every 2 or 3 days it gets started and driven around for about half an hour. sometimes more. I have always run 87 octane trough it since the rebuild. About 5 years ago.
Now since ive been running it less it has started crapping out some of the time. ill go out to start it after about 4 days of sitting and it takes about 5 minutes of priming and cranking to finally get it started. When it starts i have to keep mu foot down while it barley stays alive. i have to do this for about 5-6 minutes while it smokes like a mother. After about 6 minutes of this it finally gets better and runs perfectly fine. i can kill it and itll start right up every single time after that til it sits a while.

My question is what could cause this? Could my choke be off or should i rebuild my carb again?
I have a 4bbl Holley with a manual choke waiting for me (free) but its going to take me a while to get the new 4bbl intake manifold for $435. So id like this carb to work fine till i get it on the road this January.

Any help will be greatly appreciated. Thanks ya'll.

 

I'v used that carb a lot ,have a couple in use now and never had that problem. I'v heard of others having that problem with other carbs and some of them put a 1" heat spacer under the carb. They said the heat from the engine was doing it, best i can do but it is something to think about.


EDIT, I checked your C.B. out, looks good .

 

Ive been planning on the spacer for quite some time but have never gotten to it. Could that also effect its starting after sitting for a while?

And thanks

 

I think there may be a few issues going on...

1. The hot start/vapor lock issue as discussed.
2. Whatever fuel is in the carb evaporates or is boiled out after the last run.
3. The fuel pump could have an internal leak allowing whatever fuel in the line between the carb and pump to back drain. 'Sounds like the fuel pump is having trouble priming cuz it's dry. Hence, the long crank time before the fuel bowl can get filled up.
4. Does the white smoke smell sweet? As in coolant-smelling sweet? If not, I figure it is just condensation forming in the exhaust system. It goes away after it is up to temp, right? And there is no drop in coolant level?

 

Ive heard of vapor lock but never understood what it is. Can you explain?

I know the carb is boiling over. the pump has a very small leak. Small enough to not be able to tell where its from. But if it stays in 1 spot for the night the ground is spotted with gas right under it. No drop in coolant level. And the oil doesn't smell sweet. The next time i get it going ill get back to you on a certain smell.

If this helps any i have a 2.5 inch flowmaster 40 with a 2.5 inch tip exiting under and to she side of the cab at this point in time. But it still did this when i hhad the flow40 and a 2 inch pipe all the way to the rear.

 

Vapor lock is when the fuel is vaporized in the fuel line or carburetor due to intense heat.

Not the oil smelling sweet.. does the white smoke out of the exhaust smell sweet (as in coolant-smelling) ? Is it actually smoke or is it steam from condensation in the exhaust tubing?

 

Sorry ment to say smoke. No the smoke does not smell sweet. And im 90% sure its smoke. It smells like oil a bit. Oil and old truck exhaust

 

Also how can you tell if its vapor locked? or locking?

 

I had the same issue on my crew cab, until I replaced the 2100 with a Holley 2 bbl. and that ended the fuel perc problem. I've owned more of those pickups than I can count and only ever had a problem with one other, a 68 that liked to vapour lock after a heat soak.

 

Vapor "lock" is not a violent as you may think. Just means the fuel has evaporated out of the carb and left it dry(hard to start).

The heat from the engine(these trucks get HOT under the hood) basically cooks the fuel. It bubbles over into the engine(flooding it basically) and then evaporating what is left in the carb. These actions make it difficult to restart(no fuel and flooded all at the same time).

You need to get an isolater spacer under the carb to help with heat.

If there is fuel dripping out of fuel pump you need to replace it very soon. That will eventually make into your oil and that is not a good thing. The rubber diaphram inside the pump could be brittle and the fuel will leak to the other side and get into the oil. Oil thinned down with gas is not good on bearings or rings.

I've had a few trucks with this issue. I had real mechanical temp gauges and you could watch them climb after shutting truck off in the summer. You need to isolate the carb better.

 

If not pump then you maybe sucking air & your leak gas at the rubber line going to the fuel pump.. This one and the other rubber gas line at the under side of cab that connects hard line to tank line going into cab A.....common Problem orich

 

well my dad told me something interesting today. Ive never though about it until now.

The flash point of gasoline is about 140 +/- degrees. Where as diesels flash point is between 126 and 205 degrees.

Now my dad has had 12 fords with FE 3660's and 8 with 390. And a mix of other engines. also being a mechanic and now a industrial driller that works with chemicals and explosive gases he let me in on his secret.

What he has done with every one of his trucks is either adding a splash of diesel to a full tank so its flash point increases. Or ad a cooling cup. A sealed steel container filled with a copper tube(gas line) and water. So that the water helps keep the gas cold.

What do ya'll think about this? do either of these sound like a good idea?

 

I would not put diesel in the tank. A "cool can" was a popular race car item back in the day. Now it is obsolete. Unless you keep some ice handy the alum can will heat soak under the hood and give you more fits.

 

Sound like the old Acetone trick to get better mileage that many guys tested and found little to no improvement.. orich

 

The spacer is missing...as it had one originally: D1TZ-9A589-A .. 2V Carburetor Spacer / Obsolete

Applications: 1971/72 F100/350 360/390.

NOS PARTS SOURCE in Olathe KS has 1 = 913-220-5746.

KLIMESH MOTOR SALES in Calmar IA has 1 = 563-562-3241.

WESLEY OBSOLETE PARTS in Liberty KY has 2 = 606-787-5293.