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Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: American Mel ()
Date: February 06, 2019 07:18PM

I have heard a LOT of Hearsay about center-mount 4 barrel set-ups on Corvairs.
The biggest negative that keeps getting reported is, . . .
"You can't run them when the temps drop below 50° because they will ICE UP!"
Well, I truly do not know what to make of this statement.
My (still new to me) '67 Moredoor came with a Holley 390 on a Center-mount manifold, and I have not had any problems with it yet.
Temps have been below 50° for a couple months now, AND . . .
We have been having an extremely COLD week (for us) with temps staying below freezing ALL day.
My front porch thermometer was reading 22° when I went to work this morning.
It had dropped to 20° when I came home for lunch.
And it had risen to a Balmy 26° when I got home tonight!
This is the 3rd. vehicle that I have run with a center-mount.
The Moredoor, a PG, and the other a 4spd., no terrible issues to report.
No PICS, or it didn't happen right?
Well, here ya go.
OH! And just for the record, as I was writing this I went outside and checked, . . .
Yep, it still has the Summer cover in place.
I forgot to open it this fall!

.
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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.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater
'67 A/C Moredoor Monza - 140 4-spd. driver

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: Charlie Kelly ()
Date: February 06, 2019 09:14PM

I've only experienced icy carbs when the air is still very humid and the moisture touches the even colder carb. I'd say just the heat of the air around the engine would prevent icing.

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: vairmech ()
Date: February 07, 2019 04:41AM

I can't say that I have ever had carb icing on a center mount, actually I have on the outside but not noticeable/detrimental on the inside. I have had regular Corvair carbs ice! That happens more on the FC's unless you have the shields for the carbs installed.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: Mel ()
Date: February 07, 2019 05:16AM

I would think the old school center mounts that are heated with HOT engine oil would work quite well smiling smiley

Orangeville, Ontario. CANADA

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: Spectre ()
Date: February 07, 2019 05:37AM

When I ran a centermount, I only had ice on one occasion and it was cold and very humid.

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

Click for Norman, Oklahoma Forecast

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: JimBrandberg ()
Date: February 07, 2019 05:41AM

My 6-tube Holley 390 manifold on my road racing car is very cold to the touch even on a hot summer day.
When we ice raced a center mount 4-leg Holley we ran warm air to the air cleaner with a Ford thermostatically controlled air cleaner.
Both worked well. On the road racing car I did some testing with warm air to a different air cleaner but never really ran it. There can be some very cold races in the Spring and Fall.

As I understand it, the cold manifold is caused by fuel that comes out of suspension and then evaporates again. The fuel tends to come out of suspension when it makes a turn. There's 2 or 3 right angle turns the air/fuel mixture has to make with a center mount on a Corvair.

I have 3 or more 4-leg manifolds with different carburetors that I'd like to research when I can find the time with an eye to warming when needed.

I'm glad you're having good fortune in cold weather. Sometimes as a group we get caught up in a story like carburetor icing and turn it into tradition or rule of thumb without due course.

When daily driving Corvairs through Minnesota winters, I would run a LM air cleaner getting it's air through a hose routed above the damper door on the right side. I could just move or remove the hose when we were having a heat wave. I also used a "Chevelle with AC" heater fan running off a relay but that's another story.

Jim Brandberg
Isanti, MN
CorvairRepair.com

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: scottymac ()
Date: February 07, 2019 09:49AM

Back in the Seventies when my car was first put together in Grand Forks, North Dakota, Ben Adam's shop came up with this solution. (Anybody that races in eastern N. Dakota or northwestern Minnesota knows Ben.) A substitute cover for the hot air vent below the oil cooler was fabbed, with a small snorkel. A flexible hose connected that to a generic GM four barrel air cleaner. I believe the thermostatic flapper in the air cleaner snorkel was propped open. I don't recall ever having problems with icing with this setup. The four barrel setup was sold after my Air Force discharge, jobs were hard to find in 1980.

Scott
'65 Corsa basket case
'66 Monza coupe

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: cnicol ()
Date: February 07, 2019 10:17AM

I had and used a couple of 4-bbl conversion cars when I lived in Southern California.

The Solar Sprint (Holley 390) never missed a beat; it was very well dialed in and had no crutches to keep the tubes warm but it was used mostly in the much warmer L.A. Basin.

A '66 Corsa convertible I had for a while also had a 4bbl (AFcool smiley but at that time I was living in a cooler, fog-ridden apartment on the ocean. That car was miserable and the chilly manifold tubes were frequently covered with condensation. Driveabilty below 2000/2500 rpm was basically not there.

I currently have a set of manifold tubes that actually rusted-out due to condensation.

I guess it's safe to say 4-bbl conversions are a mixed bag and no doubt relative humidity and dew point factor into their success or failure.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: chanceparker ()
Date: February 07, 2019 10:20AM

I definitely think it's a humidity thing. I had 2 different 140's with center-mounted Quadrajets and drove them 365 days a year while going to college in Utah. it got plenty cold but humidity is very low. Never had any issues at all.

Chance Parker
Golden, Colorado
Auminum LS-powered 1965 Corsa Convertible




More Pictures

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: Gregory_Miller ()
Date: February 08, 2019 10:09AM

The only real issues I had with the Holley 4 my dad put on our 68 when I was a kid was lag when you opened the throttles, maybe too much CFM? and the poorly designed cable that kept breaking under the car. I still like my 4 1 barrels better based ion that experience.

Greg Miller
Eugene, Oregon

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: hardcase ()
Date: February 08, 2019 12:08PM

I had a '76 VW Rabbit that would ice up in high humidity/cold weather. Driving between Boise, Idaho and the University of Idaho in Moscow during the winter in the early '80s was always an adventure, because the doggone thing would freeze up solid.

My '61 Dodge D100 with a long runner slant six intake has a great solution for this, which is a physical connection to the exhaust manifold at the base of the carb, to heat the air/fuel mix.

I solved the Rabbit problem by selling it.

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: v8vair ()
Date: February 08, 2019 12:21PM

Fuel mixtures don't like going around turns.Nearly horizontal tubes making a 90 degree turn ??? A center mount will never be as good as four good functioning stock carbs. Plus a 390 flows no better than the 4 stock carbs anyway. They hurt Horse power, maybe a bit more mid range torque, but it needs a rich mixture to achieve even that. Looks cool but that's about it. My opinion, yours may vary smiling smiley Mike

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: Willt65 ()
Date: February 08, 2019 12:27PM

v8vair Wrote:
-------------------------------------------------------
> Fuel mixtures don't like going around turns.Nearly
> horizontal tubes making a 90 degree turn ??? A
> center mount will never be as good as four good
> functioning stock carbs. Plus a 390 flows no
> better than the 4 stock carbs anyway. They hurt
> Horse power, maybe a bit more mid range torque,
> but it needs a rich mixture to achieve even that.
> Looks cool but that's about it. My opinion, yours
> may vary smiling smiley Mike

Just curious, what's you opinion on the 6 into 1 intake with the 750 quadrajet?
These ports have a ram effect to help out, and the 750 has small primary's.
Still don't have mine on the road. I am planning on plumbing hot oil around the base of the intake to fight the icing problem.

Will Teeter
Flintstone, MD
65 Corsa project

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Date: February 09, 2019 09:22AM

I helped a friend do a Center mount on his 140. We used one of these (2 years ago) it works perfectly (silicone heating pad for 3d printer)

[www.ebay.com]

He used a 2 part Epoxy to bond it to the bottom of the plenum. Car is driven a ton and never an issue.

Its just run off a switched 12V on the harness with an inline fuse and a switch under the dash. Extra oil lines and fittings.. no thanks..

Some of you forget that the corvair world is a LOT bigger then this forum.

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: American Mel ()
Date: February 09, 2019 10:44AM

I think you missed the point.
I have NO, ZERO, ZIP, ZILCH, NADA, NOTHING, per-heating my intake.
I do not even have the Summer cover removed.
Nuttin but cold air in my engine compartment!
We have been experiencing temps in the twenties, with highs hovering right around freezing.
As for moisture in the air, I live about a mile from Puget Sound, and work at our local marina, yeah, I am near the water!
I don't need no new-fangled high-tech plenum heater, oil an old school oil heated one.
And to quote a recent poster on this thread, "Car is driven a ton and never an issue."


I don't think that anyone on here has even begun to imply that there is no world outside of Corvair Center Forum. confused smiley

But those of us in the know, acknowledge that it is called "Corvair CENTER Forum" because the world/universe revolves around CCF ! ! ! spinning smiley sticking its tongue out grinning smiley spinning smiley sticking its tongue out

.
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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.
'66 Monza Coupe - 4spd, 140 Daily driver beater
'67 Monza Vert. - PG, 140 Daily driver beater
'67 A/C Moredoor Monza - 140 4-spd. driver

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: Mel ()
Date: February 10, 2019 10:29AM

I still think a bit of heat would make it run even better smiling smiley I like the idea of free engine oil heat smiling smiley

Orangeville, Ontario. CANADA

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: MattNall ()
Date: February 10, 2019 10:50AM

Jonathan McCreery Wrote:
-------------------------------------------------------
> I helped a friend do a Center mount on his 140.
> We used one of these (2 years ago) it works
> perfectly (silicone heating pad for 3d printer)
>
> [www.ebay.com]
> ater-Pad-3D-Printer-Heated-Bed-w-3M-PSA-Thermistor
> /271614085178?hash=item3f3d76083a:g:ux8AAOSwQItUH7
> 51:rk:15:pf:0
>
> He used a 2 part Epoxy to bond it to the bottom of
> the plenum. Car is driven a ton and never an
> issue.
>
> Its just run off a switched 12V on the harness
> with an inline fuse and a switch under the dash.
> Extra oil lines and fittings.. no thanks..
>
> Some of you forget that the corvair world is a LOT
> bigger then this forum.
======================================================

Jonathan, it would've been nice of you to SHARE this info two years ago!! gg





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: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: cnicol ()
Date: February 10, 2019 11:08AM

Fuel volatility has increased since the days of open vent carburetors and fuel tanks. This is why our open vent carburetors dry up in a few days.

With today's closed systems, increased volatility allows an engine to start easily and has emissions benefits. I wonder if this volatility is helping to prevent fuel mixture condensation inside the cool intake tubes?

I wouldn't expect any difference in external water-vapor condensation but increased volatility might be why central-carburetor driveability seems better these days.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: chris ()
Date: February 11, 2019 08:14PM

[www.holley.com]

Is Holley hybridizing their traditional style with others (small primaries, huge secondaries, fuel bowl gasket on top)? 625 cfm seems like a lot but since it has small primaries/big secondaries it seems somewhat like a Quadrajet to me.

'65 Monza 4 door
4 speed
110hp
Gardner, KS

Heart of America Corvair Owners Association

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Re: Center-Mount 4 Barrel, Hearsay eye rolling smiley VS Reality cool smiley
Posted by: MattNall ()
Date: February 11, 2019 08:17PM

Holley bought rights to Carter AFb's and Rochester QuadraJets...





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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