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140HP Vapor Locking?
Posted by: MtnVairMike ()
Date: March 10, 2017 12:13PM

Once is a rare while I get a brief dropout when pulling off from a light with my 66.
Runs great under all other conditions.

Yesterday after getting off the interstate and stopping at a friend's work parking lot I left it idling while we talked.
In about five minutes it stopped dead. No signs, burps, farts or noises. Running 93 octane in it and fresh gas.

I left it alone for about 5 more minutes while we talked and it started and ran fine on the way home.

Seems to be only when I am at low RPMs after extended heated runs.

OK experts weigh in with thoughts, suggestions, opposing viewpoints etc.

Thanks,

Mike

1966 Monza Convertible, 140HP-4 speed, Ermine White

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Re: 140HP Vapor Locking?
Posted by: Mike Stillwell ()
Date: March 10, 2017 12:27PM

I dunno, I had one that would vapor lock, but it was only when it was pretty warm out (85F+). I ended up rebuilding the carbs and going up a jet size. That cured it. Generally they do not overheat while they are sitting running, but instead, do not want to start up after they were shut off, as the heat soak boils the gas out of the carbs. Are you running lower shrouds?
I'd pull the air cleaner off the next time it does it and work the carb linkage to make sure whether it's squirting gas or not. It still could be vapor lock, but my gut says it could be something else.

Mike
YS-117

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Re: 140HP Vapor Locking?
Posted by: Wagon Master ()
Date: March 10, 2017 12:39PM

Seems to be only when I am at low RPMs after extended heated runs.

How low is your low idle and are you running a Petronix ignition? Seems heat and too low of an idle (below 700 rpm) are both enemies of this ignition. Easy place to start your troubleshooting.

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Re: 140HP Vapor Locking?
Posted by: MattNall ()
Date: March 10, 2017 12:40PM

I'd say a weak fuelpump

When you left it idling for several minutes... the Fan was turning and keeping things cooler...no carb boil, etc...

Can you post apic of your engine compartment looking straight down. We can see if anything is missing..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..................................PG........................................................Turbo

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Re: 140HP Vapor Locking?
Posted by: gnvair ()
Date: March 10, 2017 12:51PM

Vacuum leak
Carburetor synchronization
Low float level
Misfiring (plugs, wires)
Points/distributor issue.
If it was a weak fuel pump it probably would do it all the time including when driving.

Lee J
Southern New Jersey near Philly.
1966 Corsa 180/4 speed
1969 Monza convertible 140/4 speed

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Re: 140HP Vapor Locking?
Posted by: MattNall ()
Date: March 10, 2017 02:35PM

I've made it home a couple of times with poppet valve loose in a Mech. pump!


Just had to keep the engine revv'd





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..................................PG........................................................Turbo

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Re: 140HP Vapor Locking?
Posted by: BobV66Vair ()
Date: March 10, 2017 03:48PM

It's been a while but the last time I had vapor lock it turned out to be an old, dirty fuel filter. Those little brass filters in the carbs can look OK but still not supply enough fuel. It does seem odd that it runs great at high speeds when fuel draw would be the highest. Just tossing it out there.

Bob Vinnacombe
Sandy, Oregon
1965 Corsa 140 stock
1966 Monza Soon to be race car
1968 Monza Parts for now

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Re: 140HP Vapor Locking?
Posted by: vairTer ()
Date: March 11, 2017 02:08PM

This is perhaps not exactly relevant to your situation, but here's an experience I had with a 140.

After I installed Roger Parent's excellent throttle linkage on my 4-carb 140, I eventually started to have a significant stumble when aggressively accelerating from a stop. I discovered that part of the linkage operating one of the secondary carbs was sticking and preventing the secondary carb from opening properly on only one side (but the other secondary was still opening properly). When I put a bit of lube on the mechanism so that both secondary carbs opened in tandem, the stumble went away.

I imagine this would only be a problem if the gas pedal was being depressed rapidly enough so that the secondary carbs were attempting to open.

You probably don't have Roger's linkage, but maybe your symptom of "dropping out when pulling off from a light" is due to an imbalance in the operation of your secondary carbs. Perhaps one side is stuck closed and the other isn't...

Just a thought...

Terry

1966 Monza PG convertible
Ventura County, CA

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Re: 140HP Vapor Locking?
Posted by: MtnVairMike ()
Date: March 11, 2017 02:34PM

Thanks to everyone. Still gathering info from this thread so keep answering

Here is what I can add to answer the questions so far

Std ignition no Petronix
Not starting off from the light by opening the secondaries
Car is new to me from October with a lot of storage prior to that so a lot of things to check out maintenance wise
Runs strong and seems to have the secondaries kicking in at the right time
No surges on the interstate or at part throttle

Thanks

Btw see a lot of you at Helen GA show



Mike

1966 Monza Convertible, 140HP-4 speed, Ermine White

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Re: 140HP Vapor Locking?
Posted by: TIBCO ()
Date: March 13, 2017 08:07PM

when you come to Helen for the Springfest, be sure to bring your car. there will be plenty of help there.winking smiley

Cliff Tibbitts
Lexington, KY
CORSA, CKCE
66 Monza, 140/4sp

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Re: 140HP Vapor Locking?
Posted by: JimBrandberg ()
Date: March 15, 2017 05:13AM

The time in the parking lot when it quit, I would expect if the carburetors ran out of gas you would have to crank it over for a while before it would start. If it does it again, check for an acccelerator pump squirt. I think the level where it will not squirt is higher than the level where the main jet will run dry.
Just a thought and it gets you back to the top again.
Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: 140HP Vapor Locking?
Posted by: MtnVairMike ()
Date: March 18, 2017 01:52PM

OK folks thanks first for all the ideas. I have about an hour in the garage this afternoon to look into all the great suggestions and report back. Here is what I found out in no particular order.

Both chokes set correctly cold with the engine off, right one was open a bit more than the left.
Vacuum pump confirmed both choke pulloffs worked, right one may have a slight vacuum leak but it was very slow on the gauge.
Started engine, a little grumpy cold as always.
Both choke pulloffs were completely closed.
Chokes opened as the engine warmed up.
When fully warm I checked the accel pumps on both primaries
With a good snap of the main pedal rod had plenty of gas spray and nice pattern out of each.
Even manually gave each secondary a snap of their individual rods, engine bogged as you can imagine but both gave a nice squirt of gas and engine RPM picked up after the bogging.

Now for the interesting part, and maybe I'm going down a dirt road here but stay with me.....
I was checking the vacuum advance hose to see if it was on and my hand touched the noise suppression capacitor/condenser bolt to the coil. Wowsy was it hot. Made me wonder so I touched the coil. Could barely stand to touch it too hot for sure.

Now what could it be? We under the coil I felt a hot blast of air. Seems there is a shroud opening about 1" by 2" under the coil and it was getting a direct hot blast of air from under the turkey roaster shroud.

Seems to my mind that coils don't like to run too hot. Is there supposed to be a plug in that opening? Maybe I'm overheating the coil.
To my mind a coil getting too hot could cause ignition dropout under certain conditions and definitely the stopping while idling for a while after a long interstate blast.

What say the aircooled experts?

Thanks,

Mike

1966 Monza Convertible, 140HP-4 speed, Ermine White

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Re: 140HP Vapor Locking?
Posted by: steve c goodman ()
Date: March 18, 2017 02:02PM

Most of us move the coil from the head to the brace by license plate. Same place as A/C and smog cars. Fab a small metal strip to cover hole In cooling tin, too.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC



Edited 1 time(s). Last edit at 03/18/2017 02:25PM by MattNall.

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Re: 140HP Vapor Locking?
Posted by: MtnVairMike ()
Date: March 18, 2017 02:40PM

steve c goodman Wrote:
-------------------------------------------------------
> Most of us move the coil from the head to the
> brace by license plate. Same place as A/C and smog
> cars. Fab a small metal strip to cover hole In
> cooling tin, too.


Neat suggestion!

Thanks

Mike

1966 Monza Convertible, 140HP-4 speed, Ermine White

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Re: 140HP Vapor Locking?
Posted by: MtnVairMike ()
Date: March 21, 2017 06:04AM

Well another evening in the garage and help from my friend Bob. Attached are two photos, one of mine built in April 66 with the hole under the coil open. Another of Bob's built in Feb 66 with a cover plate bolted over the hole under the coil.

Now to find either the pn, a photo or sketch of that plate so I can make/buy one.
Any one see one of these before?

Thanks,

Mike





1966 Monza Convertible, 140HP-4 speed, Ermine White

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Re: 140HP Vapor Locking?
Posted by: gnvair ()
Date: March 21, 2017 06:32AM

MtnVairMike Wrote:
-------------------------------------------------------
> Well another evening in the garage and help from
> my friend Bob. Attached are two photos, one of
> mine built in April 66 with the hole under the
> coil open. Another of Bob's built in Feb 66 with
> a cover plate bolted over the hole under the
> coil.
>
> Now to find either the pn, a photo or sketch of
> that plate so I can make/buy one.
> Any one see one of these before?
>
> Thanks,
>
> Mike
>
> [c1.staticflickr.com]
> d91e86e_z.jpg
>
> [c1.staticflickr.com]
> 3e1090d_z.jpg


That is a home made cover. GM never had a cover for that hole.
I responded to you on the other message board but I will note this......
All of the 140's and turbos that I have had that appeared to be untouched including my March 66 turbo had the slot in the right side damper door housing under the coil.
I have found 95's and 110's with and without it. GM listed both numbers in the parts catalog but they did not detail which engines would have it.
It doesn't typically hurt anything and had to have a purpose but I have never seen anyone post what that purpose is.

Lee J
Southern New Jersey near Philly.
1966 Corsa 180/4 speed
1969 Monza convertible 140/4 speed

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Re: 140HP Vapor Locking?
Posted by: steve c goodman ()
Date: March 21, 2017 07:47AM

The slot is for smog plumbing.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo 1965 Crown V8
1967 monza 110/4 1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC

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Re: 140HP Vapor Locking?
Posted by: gnvair ()
Date: March 21, 2017 08:03AM

steve c goodman Wrote:
-------------------------------------------------------
> The slot is for smog plumbing.

Why would it be on 65 and 66 model year cars that never had smog? I know smog started in 66 on California cars but back east any LA built car is a very rare commodity. Like I stated earlier, my 66 turbo had it as well.

Lee J
Southern New Jersey near Philly.
1966 Corsa 180/4 speed
1969 Monza convertible 140/4 speed

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Re: 140HP Vapor Locking?
Posted by: 4carbcorvair ()
Date: March 21, 2017 09:04AM

My early built 66 (late 65) has the slot.

Not sure if your problem is vapor lock or your coil. In 06 at the Buffalo convention, I had horrible issues with vapor lock on my 140 on the way out. Slowing down at a toll plaza would cause the car to sputter and almost die, had all I could do to keep it running for a minute until it came out of it. If I stopped, I had to allow time for it to cool. I had to change the fuel pump on the way, so that got ruled out. Almost to buffalo someone suggested tin foil on the fuel lines in the engine compartment as a temp fix, definitely helped until I got home. Tried another fuel pump, check carbs, chokes, etc... The only thing that worked and I have honestly never had another issue with vapor lock was installing an electric fuel pump. This worked for me, you will have to do some more testing/trial and error until you find the issue. One thing to check, when it stalls out and won't start, check for fuel flow out of your accelerator pumps, make sure they are squirting. If not, you know it's a fuel issue.

--------------------------------
Ronnie
Southern Maine.
[www.dirigocorvairs.com]
66 Corsa Convertible, 140, 4sp.
65 Monza Convertible, 110, PG.




It doesn't leak, it's marking it's territory.

A mirror is a reflection of the miles travelled.

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Re: 140HP Vapor Locking?
Posted by: MtnVairMike ()
Date: March 21, 2017 10:04AM

Lee,

Thanks for responding twice, as you probably realized not everyone is on the same forum. Does look homemade now that you mention it. Also makes sense that cars with AC or AIR have the coil relocated to the back of the license plate panel inside since this slot and the coil space would be filled up with AIR hoses and the air pump. Since the coil is getting too hot to even touch and the air through the slot under the coil is like a hairdryer on med-hi it can't be good.

Steve,

That definitely makes sense why the slot is there. Puzzling since my car was a Willow Run build and spent a lot of it's life back East. Maybe they had a bunch of extra West Coast pans lying around, LOL.

Ronnie,

I have eliminated the vapor lock theory. The car has never had a problem starting back and running fine. I have another post from someone on the Corvair Forum that had the exact same problem/cure from overheating a coil. If a coil gets too hot the wire resistance climbs and the spark output drops until it doesn't want to run.

[www.corvairforum.com]


Thanks to all.

Mike

1966 Monza Convertible, 140HP-4 speed, Ermine White

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