Vapor Lock on 1966 Toronado

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Tuco
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Years Owned: 1966 Toronado
1951 Cadillac
1957 Pontiac
1965 Impala

Re: Vapor Lock on 1966 Toronado

Postby Tuco » Wed Sep 30, 2020 6:18 am

I’m not sure about all circuits. And I’m not sure that I have any experience with Daytona but I’ve had to adjust the idle air mixture on just about every carb I’ve had done.

The latest was on a 347 Pontiac that I rebuilt. Got the carbs back and ran the engine. It was lean and running hot. Adjusted the center carb and it was good.

Same with my Toro. Had the carb rebuilt and it was running too rich.

I don’t know that it will help but it’s a simple thing to try.

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Otto Skorzeny
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Re: Vapor Lock on 1966 Toronado

Postby Otto Skorzeny » Wed Sep 30, 2020 11:32 am

The car runs so well that I'm reluctant to fiddle with it but I will if I have to.

Are there any other symptoms of a lean carb? I know what a too rich exhaust smells like but are there any signs of too lean?

Schurkey
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Re: Vapor Lock on 1966 Toronado

Postby Schurkey » Sun Oct 11, 2020 4:10 pm

Stuck heat-riser valve? Restricted side on a dual-exhaust system? Either one will force excess exhaust gas through the exhaust crossover in the intake manifold, and BAKE the carburetor. If this is what's happening, your carb and carb gaskets are in danger.

There is so much heat in the exhaust crossover that aluminum manifolds could actually burn-though. Think about the melting point of aluminum!

GM used double-wall exhaust tube. It was possible for the inner wall to collapse while the outer wall looked fine. You'd have to cut the tubing to find the collapsed inner wall--but you could test for exhaust restriction. Again, if one side of a dual exhaust was restricted, the exhaust is forced across the exhaust crossover in the intake manifold.

There are inexpensive heat shields that can reduce carb temperature; if the heat riser isn't defective you could try one. Will probably need some custom-trimming of the aluminum plate. Or just buy some aluminum sheet and make your own. An aluminum cookie-sheet and a couple gaskets, tin-snips, drill and bits, and some labor. Hood clearance on Toros is tight, but these heat shields should be less than half-an-inch thick.

https://www.summitracing.com/parts/opg-87a0211
Image

Holley used to sell one very much like what I posted above, as did GM themselves. Mr Gasket (a division of Holley) still sells one, but it's likely it'd need even-more custom trimming than the one above.

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Otto Skorzeny
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Re: Vapor Lock on 1966 Toronado

Postby Otto Skorzeny » Mon Oct 12, 2020 2:18 pm

Unfortunately, due to the unique shape of the Toronado intake manifold, a heat shield won't work. The carburetor mounting base sits lower than the height of the intake runners. They rise from the intake just about 1/2" from the edge of the carb.

A half inch phenolic spacer may raise the carb high enough for the shield to clear.

I put a blob of plumbers putty on the top of the air cleaner and closed the hood. It mashed down to slightly less than 3/4".

I intend to purchase a 1/2" spacer and intsall it. If the shield fits, I'll put it on, too.

The exhaustheat valve on the driver side works perfectly but I unhooked it to be on the safe side. If nothing else works I intend to remove the intake manifold and install plugs in the crossover holes of each head.
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Otto Skorzeny
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Re: Vapor Lock on 1966 Toronado

Postby Otto Skorzeny » Thu Feb 04, 2021 7:47 am

OK, get a load of this.

All this time the assumption has been that the problem is vapor lock. No fuel in the carburetor 30 minutes after shutdown. Working the throttle by hand and peering down the throat revealed that no fuel was squirting from the jets.

After the fuel that remained in the fuel boal burned off, the car would not get more gas until it sat for a couple hours and cooled down.

Underhood temps are not out of the ordinary, nor are individual components. The car did not experience any negative problems while driving. The problem only presented itself after it sat for 20 or 30 minutes after being driven.

Fuel pump was replaced twice. A vapor return line was installed, a new fuel line to the tank was installed. Carburetor rebuilt once to 66 Toro spec. Carb sent back and inspected. New needle and seat installed even though no problems were found with existing ones. I even took advice from others who swore an electric pump would push through the air bubble and get the fuel into the carb. Nope.
Fuel tank removed from system and replaced with temporary tank under the hood had no effect.

I removed the fuel line from the carb inlet when problem presented itself. There was a dribble of fuel but mostly air. Vapor lock, right?

I installed a hose on the inlet and attempted to blow air into the carburetor. I puffed up like Louis Armstrong and could not get air into the carb. I had to use compressed air to unstick the needle valve from its seat to allow air into the carb!

What the heck??? How can this be stuck in the seat so hard that a 9psi fuel pump can't push fuel into the carb?

Carburetor was disassembled but no problems were found. Float was fine with no binding of the float arm or interference of any kind. Needle and seat showed no unusual wear or marks or defects of any kind. This was the third needle and seat installed during this entire problem and stuck the first time the car was run - so it wasn't worn out or anything.

The only solution was to install a steel tipped needle instead of a rubber tipped needle since there is no possible way for a steel needle to stick in a steel seat.

The problem went away immediately.

What the heck is going on that a rubber tipped needle that's used in thousands of Q jets without problems apparently swells up so much in my car that it firmly embeds itself in its seat and can't be dislodged with normal operating fuel pressure?

The only thing I can think of is that the carb is heating up after shutdown to a point that the rubber swells so much it jams itself in the seat.

Schurkey
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Re: Vapor Lock on 1966 Toronado

Postby Schurkey » Thu Feb 04, 2021 2:35 pm

I have long suspected--without proof--that "somebody" or groups of "somebodies" are disposing of industrial waste by dumping it into the gasoline supply. We the People are forced to run that crap through our catalytic converters in order to save Industry the cost of proper disposal.

The contaminant is raising hell with people's cars, and the owner's are blaming "Ethanol" for those problems created by some other chemical(s).

But what the hell do I know? It could be a matter of Communist Chinese defective Viton being used to make carburetor parts like the needles.

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Otto Skorzeny
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Re: Vapor Lock on 1966 Toronado

Postby Otto Skorzeny » Thu Feb 04, 2021 4:43 pm

What's weird is that not a single one of my other vehicles - all of which are 40-65 years old (I don't own any modern cars) - don't have any problems at all with this crap gas.None of them have Cats, either!

I've been driving my '56 Coupe de Ville as my main driver for 20 years and never had vapor lock or driveability issues. When the Feds mandated ethanol in Metro Atlanta in 2007, it killed the original fuel pump in a matter of months. The diaphragm swelled up and would only pump half the requisite volume.

After it was replaced with a ethanol proof pump its been fine.

You're probably right about the Viton. Daytona Parts Co which rebuilt the Toro carb (actually all the carbs on my vehicles) told me the Viton was very high quality when made in the USA. The company that made all the needles then moved the production to Mexico. Even then, he said, the needles were good quality.

The company then moved the facility to Asia somewhere - probably China - and there's no way to tell what kind of quality you're getting now.

He did say that he's never encountered this problem nor has he had customers complaining about stuck needles in any of his carbs so I think there's something unique going on with my car.

My guess is that whatever the problem is, it is compounded by today's modern fuel and the inferior components in carburetors and fuel systems. Where's that Tetra-ethyl Lead when you need it?


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