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1968 Corvair floods after hot shutdown?
Posted by: me654hunting ()
Date: September 14, 2020 07:53AM

i have a 1968 corvair with a 140 hp motor 4 speed the motor is set up for a 4 bbl. holley what the problem is after running the motor and shut it off the heat from the motor boils the gas and makes it flood what kind of matreial can i use for a heat shield so i can put it on the bottom of the intake part thanks mike



Edited 1 time(s). Last edit at 09/16/2020 08:16PM by MattNall.

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Re: 1968 corvair
Posted by: pvholgado ()
Date: September 14, 2020 07:58AM

Don't they make a carb insulator for the Holley? Wouldn't it bolt up to the mount for the Holley? Just wondering- used to have a similar problem on several Camaros I had.

"A sign of great intelligence is being able to say 'I don't know'"
1966 Corsa Turbo Coupe current being "refurbished"
Located 25 miles East of Rochester, NY

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Re: 1968 corvair
Posted by: MattNall ()
Date: September 14, 2020 08:14AM

Insulator gaskets are available for ALL carbs.

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

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Re: 1968 corvair
Posted by: jjohnsonjo ()
Date: September 14, 2020 08:37AM

I don't think an insulator is the answer in this case. A 4bbl would already be isolated from the engine some what. Sounds like heat soak coming back up through the fan opening. Or vapor loc not replentishing the carb during hot start.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: 1968 corvair
Posted by: American Mel ()
Date: September 14, 2020 09:18AM

Gotta agree with J.O. on this.
me654hunting, try blocking the hood open about 4-6 inches when you shut her down. (a small piece of 2x4 or similar)
This will let heat escape out of the engine compartment.
See if that has any effect on what you are experiencing.

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry

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Re: 1968 corvair
Posted by: MattNall ()
Date: September 14, 2020 10:10AM

You do have all the factory sheetmetal installed? post a pic please.

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

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Re: 1968 corvair
Posted by: me654hunting ()
Date: September 14, 2020 01:54PM

the hood is open when you start it after it sets for an hour or so runs real rich after it clears up it runs fine then when you shutit off after 30 mins or so you see gas on butterflys holley techs says too much heat at the base of carb need to insulate and he is right it gets pretty hot when you shut it off new holly carb 350 cfm 2 bbl.

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Re: 1968 corvair
Posted by: me654hunting ()
Date: September 14, 2020 01:57PM

yes all sheet metal is on and in the right places it is heat coming up through the fan housing and ineed to insulate it to keep the heat away

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Re: 1968 corvair
Posted by: American Mel ()
Date: September 14, 2020 02:48PM

me654hunting, where are you located? In a HOT climate? (add a Sig-line, with location, and what Model & Engine you have)
My Holley set-up has never done anything like that.
Neither the one I have on there currently, nor the one I was running while in PDX. (which gets fairly hot in the Summer.)
I have had the fuel pump vapor-lock from heat, but never had Holley issues from the heat.

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry

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Re: 1968 corvair
Posted by: FLSteve ()
Date: September 14, 2020 06:47PM

Same here 4bbl holly never an issue here in South Florida but I do have an electric fuel pump.



American Mel Wrote:-------------------------------------------------------
> me654hunting, where are you located? In a HOT climate? (add a Sig-line, with location, and what Model & Engine you have)
> My Holley set-up has never done anything like that.
> Neither the one I have on there currently, nor the one I was running while in PDX. (which gets fairly hot in the Summer.)
> I have had the fuel pump vapor-lock from heat, but never had Holley issues from the heat.

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Re: 1968 corvair
Posted by: me654hunting ()
Date: September 15, 2020 05:15AM

im in southern mo. car is a monza coupe 140 hp 4 speed engine is a fresh complete rebuild cam pistons new standard cyls. bearings and rings new 350 cfm 2bbl. holley carb. the holley tech said yesterday the heat coming up through the fan housing aftre shut off is causing my problem any help would be greatly appreciated thanks mike

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Re: 1968 corvair
Posted by: me654hunting ()
Date: September 15, 2020 05:18AM

after shut off the new carb. is leaking through the butterflys it also has a electric fuel pump i have it set at 4psi and it still leaks down

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Re: 1968 corvair
Posted by: steve c goodman ()
Date: September 15, 2020 05:52AM

If you have a toggle switch to turn pump on/off then shut fuel pump off and let engine run for 30 secs then turn key off. Start up the same just let pump run for 30 sec then one one pedal stroke and start engine

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/V8 Registry

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Re: 1968 corvair
Posted by: Spectre ()
Date: September 15, 2020 06:33AM

If the carb leaks at shutoff, it sounds like a problem with the carb Float adjustment?

David Clamp


1965 Corsa convertible - 140 4spd/3.55/AM-FM

2013 Mustang GT convertible - 5.0, 6spd auto, Procharger i-1

2003 Miata SE - 6spd manual (wife's toy)

"Victory is mine!" - SG

Norman, OK



Edited 1 time(s). Last edit at 09/20/2020 02:49PM by MattNall.

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Re: 1968 corvair
Posted by: JimBrandberg ()
Date: September 15, 2020 06:42AM

I also was wondering about high fuel level in bowls. Or bowl I suppose if it's a 2-barrel.

Going O/T, I'm wondering about the choice of a 2-barrel rather than 4-barrel carburetor. Usually with a 4-barrel a person can motor around on small Primaries for fuel economy and good throttle response but have the Secondaries available when needed. I'm not saying it's bad or wrong, just wondering.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: 1968 corvair
Posted by: me654hunting ()
Date: September 15, 2020 09:32AM

brand new carb.was sent back to holley they said it was put on flow test machine everything was ok then was pressure tested they let it set for 3 days and it didn't leak down so what do you do im rasing the intake up 1/2" so it is higher don't know if it help then going to wrap intake pipes with header insulation and also the bottom of the intake with high heat inslating sheet 2 layers of that any suggestions im open for anything right now pulling my hair out ha!

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Re: 1968 corvair
Posted by: American Mel ()
Date: September 15, 2020 09:57AM

What you are describing is truly strange!
Most guys are out there trying to contrive ways to GET HEAT TO their intake.
Sounds to me like there may have been some kind of design change in how the Holley is manufactured?
It really should not need all of this Rube Goldberg stuff you are putting together.

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry

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Re: 1968 corvair
Posted by: jamesolefjensen ()
Date: September 15, 2020 01:21PM

Hear hear on the float level adjustment.

I wouldn't be surprised if the residual pressure in the fuel line after the engine is shut off is enough to push fuel into the bowl. If the fuel level in the bowl is too high, flooding could ensue. At least that's my hair brained theory.

And just in case you don't know how to spray gasoline all over your engine compartment, here's how Holley floats are checked and adjusted:

[youtu.be]

I have a 390 4 bbl on my Corsa and have never had fuel boil over. Not even in 100+ degF northern California summers with a factory warm air duct/damper style air cleaner.

James
65 Corsa
SF Bay Area

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Re: 1968 corvair
Posted by: jamesolefjensen ()
Date: September 15, 2020 01:32PM

Something like this would help keep the carb cool:

[pitstopusa.com]

James
65 Corsa
SF Bay Area

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Re: 1968 corvair
Posted by: Marco_a_p ()
Date: September 16, 2020 05:14PM

Is it a center pivot or side pivot bowls on that Holley 4bbl?
Are you parking the car on a slant or side tilt by chance?

Do the bowls on the newer holleys still have the "sight Plugs" on the side of the bowl to check float level?

On the ones with the "sight plugs" you unscrew the plug and look for just a trickle of fuel, just barely anything. If it's rolling out, its too high.
On V8's i'd adjust with engine running with mechanical pump, and some rags on the intake manifold to catch the fuel, but I suppose with an electric pump the pump only needs to be running. not sure how you would catch the fuel with rags on a running vair motor though eye popping smiley

Marco
A 2nd Gen Monza Wagon, a 2nd Gen GB 8door, a 2nd Gen (61's were 1st Gen) R/s and a 62nd Gen Turbo coupe..

Hanging out with the scorpions, king snakes, road runners, coyotes and quails In the southern desert of the silver state
Mesquite NV 89024

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