29 model a exhaust manifold glowing and carb vapor locking

[acjohn]

I recently went on a ride with my 29 model a, the weather was I deal 72. After riding for about 20 minutes the car started to loses power, over heat, and stall. I went right to the carburetor side and noticed that the e manifold was glowing read and carb was dripping gas. After 20 minutes or so the engine cooled down, the carb held gas and engine began to run again. while driving back I noticed that the engine would start to over heat when pushing it. My cell phone gps told me I was max speed of 42. Am I running to lean and what should I do.

[700rpm]

Where are you running your spark rod?

[Bill G]

Welcome to the Barn.

The experts might be able to zero right in on the cause. I can only get general, like check timing, carburetion, or make sure there is water or antifreeze in the radiator. My stock '29 doesn't much like going over 45 either, but it doesn't heat up like that if I push it.

Are you new to Model A ownership or have you had this car for a while. Is this a new and sudden issue with the car? What is your normal cruising speed with it?

One thing for sure, you do have a problem and it needs to be fixed.

[Jacksonlll]

An easy thing to check is the condenser. They don't often go bad, but take a different one and ground the body of it and connect the other end to the side of the coil that goes to the ignition key. It has to be in the circuit between the key and coil, the points side of the coil. If it runs good, just change the condenser. The other thing that would cause the prob is low on coolant and you ran it hot. That could cook everything.

[acjohn]

what do you mean by spark rod? Timing, spark plug gap,

[michael a]

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He was talking about your timing where did you have your liver set at at the time your engine was overheating

Sent from my SM-J700T using Tapatalk

[Gary WA]

Check this site for information on timing etc.http://modelabasics.com/home.htm

[SSsssteamer]

Running your timing retarded can make your exhaust manifold glow red. During the cold winter days, to get a little extra heat out of the exhaust manifold heater, just to make the wife happier, I will retard the spark a little.

[1crosscut]

acjohn
Has the car been running well up to now and this is a new problem that has just started? Some history and background on the car will help us help you. Are you new to Model A's?

[steve s]

Definitely check the timing first, including making sure that you've pulled the spark (left) lever down at least half way AFTER startup. I'm betting that the timing is either set too retarded or the lever has been left up (same difference).

If the carb is dripping gas, it's unlikely that you're running too lean.

The car will start and run real smoothly when retarded--for a while!

A good analogy to understand the effect of timing on overheating is to imagine yourself pushing your kid on a swing. "Retarded" timing would be like if you were always a bit late with your push--you expend all of your energy running around and chasing the swing, and it wouldn't take long to overheat. Conversely, if your timing is advanced, you're going to break your wrists crashing into that oncoming swing seat--similarly, for the wrist pins and other connections in your motor.

[Dick Steinkamp]

I see "vapor lock" in your title. What symptoms are you experiencing that lead you to believe there is vapor lock?

[Dollar Bill]

As many have already mentioned, glowing red manifold is a classic case of retarded or late timing - Most likely due to the position of the spark lever on the left side of steering wheel. Good rule of thumb, on level ground at 40-45 mph, place advance lever midway of range, At full road speed, go full advance.

Yes, a lean A/F mixture runs hotter but its very unlikely you could lean it out enough to turn the exhaust manifold red - 1100°F.

[SuperDave]

I always thought vapor lock was caused by vapor in a fuel pump. A fuel pump is designed to pump a liquid, therefor if there is vapor in it, it doesn't pump. Since the Model A is a gravity feed (no pump) a vapor lock is virtually impossible. At least that is my understanding.

[BILL WILLIAMSON]

RED hot manifold will cause fuel to BOIL, creating AIR bubbles in the carb & fuel line. This causes POOR RUNNING/STALLING & is NOT TRUE VAPOR LOCK!
RETARDED timing AND/OR lean mixture is the common reason for GLOWING manifolds.
In SOME Les Andrews books, he says that OVER RICH causes it, that's NOT TRUE, trust me!
A RESTRICTED exhaust "might" contribute to it, but that's quite RARE. AND, under these conditions, it "might" FRY the CONDENSOR!
Bill W.

[Tom Wesenberg]

Originally Posted by SuperDave

I always thought vapor lock was caused by vapor in a fuel pump. A fuel pump is designed to pump a liquid, therefor if there is vapor in it, it doesn't pump. Since the Model A is a gravity feed (no pump) a vapor lock is virtually impossible. At least that is my understanding.

With this new crap gas that boils way too easily, vapor lock is possible and does happen quite often. I've had it happen to my car, but when I buy the better gas without corn crap in it I don't have vapor lock. Sure wish we could get the good gas of the 70's, even if the lead is removed.

I used to think vapor lock couldn't happen on a gravity feed system, until it happened to my friend, then to me. That's just one of the bad things about ethanol crap gas and what it does to our cars.

[George Miller]

Vapor lock does happen with a model A. At least in this part of the country. It will not happen if you do not drive your car.

[burner31]

Originally Posted by acjohn

what do you mean by spark rod? Timing, spark plug gap,

I think he has found the issue.
Now just need a little education/information and he'll be tooling down the road just fine.

[burner31]

Originally Posted by acjohn

what do you mean by spark rod? Timing, spark plug gap,

I think he has found the issue.
Now just need a little education/information and he'll be tooling down the road just fine.

[Dick Steinkamp]

The vapor pressure of ethanol is LESS than that of gasoline. Gasoline will boil (vaporize) far before ethanol will.

"The higher the volatility of the fuel, the more likely it is that vapor lock will occur. Historically, gasoline was a more volatile distillate than it is now and was more prone to vapor lock."

"Vapor lock is also less common in other motor sports, such as Formula One and IndyCar racing, due to the use of fuel injection and alcohol fuels (ethanol or methanol), which have a lower vapor pressure than gasoline."

https://en.wikipedia.org/wiki/Vapor_lock


"Gasoline does have a latent heat of evaporation. It varies, but is usually near 145-150 BTU/lbm, substantially easier to vaporize than ethanol. "

"Automotive gasolines fall in 5 different specification volatility classes, ranging from 9 to 15 psi. All of these are considerably more volatile measures than that for ethanol. "

"Low boiling points, high RVP, and low latent heats of evaporation act to make this problem more severe. All gasolines have severe disadvantages relative to ethanol by any of these measures. In tests, neat ethanol has proven virtually impossible to vapor-lock. "

http://www.txideafarm.com/ethanol_fu...s_and_data.pdf

Ethanol does have its problems. However, an increase in vapor lock over pure gasoline is not one of them.

[Marshall V. Daut]

George -
How times have changed - and attitudes. On the old "Ahooga" website back in the early 2000's, I was trying to help diagnose a poster's problem with stalling and bucking in the summer heat and mentioned it could be a vapor lock. Jeez, Louise! Did I get roundly jumped on for that! "You can't get vapor lock in a Model A, dumb*ss!" was the standard reply, ad infinitum, ad nauseum. Posting after posting parroting the first response like that appeared in the rapidly multiplying thread. It went on for pages. All kinds of technical explanations were advanced to explain why a vapor lock wasn't possible in a Model A. A few clear heads agreed it was vapor lock, but the majority of posters decried the possibility. O.K. Let me get off the rack! If it wasn't vapor lock, what WAS causing the gasoline flow stoppage on hot days? Give me the EXACT name for this condition. Postings noticeably dropped off.
I think that was the last time I ever mentioned vapor lock on a Model A website again, although there have been numerous threads over the years since then thrashing and re-hashing this subject. It seems in the past few years that "vapor lock" is generally being accepted as a real thing in Model A's, especially since this crap Ethanol gas has taken over since the early 2000's. It doesn't really matter to me what the phenomenon is called that stops the flow of gas in our Model A's on hot days. The cure is more important. Consensus runs the gamut from using wooden clothes pins clipped to the fuel line to putting some diesel fuel in the gas tank. The latter seems to work best. As we are now in an early winter, I don't think we'll be reading too many more posts about "vapor lock" until next summer. Maybe by then, a more accepted name could be found for this condition that some agree exists, others refuse to accept.
Marshall