Interesting shot for those with vapor lock

[stouchton]

This image is from a hot day last September.

Found the fuel line interesting where it enters carb. Kind of got me thinking to insulate the fuel line.

[Patrick L.]

It appears that the photo shows the fuel with a downward pitch to it. But photos can be deceiving. Is it pitched down all the way. That has been one of my thoughts about boiling fuel.

[stouchton]

I don't think it is, but got to admit the photo sure shows it that way. I'll check and post back.

[Brian T]

I posted this 2 years ago, ---
As we mostly are concerned with carburetors that work well enough that are as sophisticated as a flush toilet, with the vaporizer just above, and the carburetor within an inch of the exhaust --- heat shields and phenolic spacers work well on my engine.

In the picture my heat shield faces directly at the exhaust manifold reducing the radiant heat to the cast iron of the carburetor, all the shields I have seen thru the years are this way, the phenolic spacer slows down the heat traveling back to the carburetor after shut down.

This reduced the carburetor temperature from 160* to 120*, another benefit was increased engine performance and perfect hot starts , I do have to admit that prior to this I never had any symptoms of vapor lock, --Go figure.

As Patrick L mentions the fuel line should always go down hill to the carb, in addition any small restriction in the line will slow volume, example cutting a fuel line with a tubing cutter will burr the inside of the pipe causing a slight restriction.

[Big hammer]

The heat is coming from the exhaust manifold above the carb and line? A rubber hose the size of the fuel line nut, leaving air around the tube might fix the heated line? I would think the line near the exhaust outlet would be very hot also.

[Tacoma Bob]

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Something I tried with success in 107 degree heat for a week was to slip a Styrofoam beer can cooler over the glass sediment bowl. I also slit rubber fuel line and placed it over the steel line with several zip ties. While my traveling group registered very high temps (using a thermal imaging gun) my rig ran many degrees cooler. It's been a number of years now and if memories serves me (LOL) I think the other cars were running close to 200 degrees. I was running 150 or less.

[2manycars]

I like that heat shield. Not original, but functional. I recently made one for my MGBGT that has a camero V6 motor.

[Mitch//pa]

The FLIR thermal imager is a great tool for unlimited uses.....
I have the one which plugs onto my I-phone

[BILL WILLIAMSON]

Does anyone try opening the R/H hood while gassing up, to keep the CARB/LINES from getting TOO HOT?
Bill W.

[V4F]

tin foil & cloths pins

[wmws]

Originally Posted by BILL WILLIAMSON

Does anyone try opening the R/H hood while gassing up, to keep the CARB/LINES from getting TOO HOT?
Bill W.

Yes I do that on a hot day. I even drove through town once on a really hot day with the right hand hood open. Lots of stop and go traffic and I had no problem with vapor lock.

[Bob Bidonde]

Why is the carburetor cool in the infrared photo? It does not make sense to me.

[gweilbaker]

There is a cooling effect in the venturi area, it's common to have icing in cool damp climates.

[Kevin in NJ]

Let us stop and ask what we are seeing in the picture!!!

What is see is not a hot fuel line, but what I would expect to see if the infrared was being reflected off the top of the fuel line.

Notice the whole fuel line is not showing heat. Only the top and you can see the front and rear edges are blue. Notice how it comes to a sharp point as you go away from the carb. Notice the thin line on top as you go around the bend. If it were a hot tube I would expect to see a different picture.

Before I make any conclusions I would need more pictures from different angles. I would also want to touch the line and see if the picture makes sense.

Remember infrared is light and it reflects like light. I believe you are just looking at the reflection of the hot manifold above the line.

[stouchton]

Kevin - good point but I checked for that. Thermocouple agreed with thermal image - was curious as to the emissivity of the surfaces (I've done thermal designs for 4 decades now). Found it interesting that the local area was showing heating.

Remainder of fuel line was cool (cool meaning slightly below underhood ambient temp).

This picture was taken on a 91 degree day after 30 minutes of running. Drove the car home from work, parked on driveway and took picture. Idling time was less than 2 or 3 minutes (FLIR takes a minute or so to boot up).

As to the earlier question about fuel line - all downhill all the way to carb.

[stouchton]

Also - I do not have a picture of this, but the copper manifold gasket raised the carb temp almost 20 degrees higher than the paper gasket.

I idled the car for 20 minutes with hood down using copper gasket. Raised hood, and checked bowl temp. Shut down, swapped gaskets, rinse and repeat. Bowl temp almost 20 degrees cooler. Do not think anything environmental effected outcome (all down in about an hour on the same day....)

Needless to say, I left the paper gasket in place.

[Kevin in NJ]

I should point out that the heat problems of the A are not common.

Over the years of listening to people who have had problems and resolved them I believe most all the vapor lock issues are just electrical/ mechanical in true nature. The vapor lock is symptom of things being improperly built. Now I will add that the modern fuels coupled with other environmental variables may cause some issues, but not consistent issues. Such as having gas mixed for the spring in a car run at 110 degrees with 98% humidity (I am making this up) might cause fuel to boil.

Overall, it is only some A's that seem to have problems.

My favorite example was the guy who had constant vapor lock issues. When the engine came apart for other issues it was found the valves were on the hairy edge of incorrectly set. With the valves being properly set the engine no longer got too hot and caused a vapor lock.

People are asking the wrong questions. They need to question what thing or combination of things being out of specs is allowing the engine to be so hot. Of course, that is the hard stuff. Doing a tear down and checking everything. It is much easier wrapping the carb or something. (Yes I know I will draw some flak for these comments, maybe one day it will sink in)

[Kevin in NJ]

Originally Posted by stouchton

Kevin - good point but I checked for that. Thermocouple agreed with thermal image - was curious as to the emissivity of the surfaces (I've done thermal designs for 4 decades now). Found it interesting that the local area was showing heating.

Remainder of fuel line was cool (cool meaning slightly below underhood ambient temp).

This picture was taken on a 91 degree day after 30 minutes of running. Drove the car home from work, parked on driveway and took picture. Idling time was less than 2 or 3 minutes (FLIR takes a minute or so to boot up).

As to the earlier question about fuel line - all downhill all the way to carb.

That is also the surface temp at idle. What about the actual fuel temp?

Plus that is just one car. What about other cars?