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Often overlooked on a carburetor rebuild...tip
Posted by: corventure Dave ()
Date: June 08, 2015 02:22PM

Here is something you won't find in most if any carburetor rebuilding instructions. Including the Rochester Products Line 9 manual.
Over the years I have had people call me with erratic carburetor performance after a rebuild. There are a few things that have been discussed here. but as I am rebuilding a pair of carburetors for a friend, I thought I would share this trick.

The Venturi cluster can and will warp over time. The worst I ever came across was in a Quadrojet!!! But even the small clusters in Corvairs can suffer from this.
First lets look at the brass tube ports on the cluster. I measure them with simple pocket rulers and mark their height installed. The individual height will be needed later.

On to page 2!

Corventure Dave

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: corventure Dave ()
Date: June 08, 2015 02:27PM

The next thing needed is a tool to extract the tubes without damaging them. I made my own with some cheap pliers. I drilled them out as shown in tow sizes to be able to grip the tubes but not crush them.
Extracting the tubes only takes a slight twist and pull. Just be sure not to bend these. also notice the perforations on the larger tube are aligned front to back on the cluster.

Corventure Dave

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: corventure Dave ()
Date: June 08, 2015 02:31PM

Now with a straight edge, check the gasket surface. This one appears to be pretty good... but wait!

Taking a piece of plate glass to provide a flat surface... and also some 400 grit sand paper.. carefully slide the venture cluster over the sandpaper. You are hand milling the gasket surface by doing this.

Corventure Dave

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: corventure Dave ()
Date: June 08, 2015 02:42PM

After just a couple passes the high and low areas will show distinctly.
A few more passes and we are getting somewhere.
Finally there is a smooth gasket surface area.

I have seen much worse clusters in Corvair carburetors. We can't do much about the gasket surface inside the carburetor, but by cleaning up the cluster side of the gasket surface, the gasket has only the cast housing surface to seal against.

Reassembly is just the reverse from disassembly. The small tube first can be carefully tapped into place, checking it's depth. Then the larger tube. Orient the perforations front and back. I use a plastic screwdriver handle to lightly tap these into proper height.
This is something I have done with carburetor rebuilds for over 30 years. It eliminates the possible leakage that can break the syphoning action of the venture cluster from the fuel well.

This hand milling technique can be used for any flat gasket surface. I have used a larger sheet of sandpaper for the rear engine cover and also the Delcotron adapter, sometimes called the Alt-Gen and oil filter adapter. It goes a long way to stopping oil leaks. Plate glass gives a good flat surface to do this.

Corventure Dave



Edited 2 time(s). Last edit at 06/08/2015 02:49PM by corventure Dave.

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: corventure Dave ()
Date: June 08, 2015 02:46PM

I wish I had more time to go back and correct my spellingz. This system locks you out real fast! Oh well. That's what I get for typing with my one eye closed and with thumbs!grinning smiley

Corventure Dave

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: 52bagman ()
Date: June 08, 2015 02:53PM

X-C-LENT

Sam C. Saunders,Pt. Pleasant WV
68 500 cp 95 pg ash gold
66 Monza cp 110 4spd black
68 500 cp 95 3spd blue "DAIRY QUEEN CAR"

1 link2 linkPhotobucket

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: rowin4 ()
Date: June 08, 2015 02:53PM

Good tip dave , As most ,I just put on a new gasket. I'll check the flatness next time I'm into the carbs

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: MattNall ()
Date: June 08, 2015 03:15PM

RTV works faster!! smoking smiley





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: Often overlooked on a carburetor rebuild...tip
Posted by: davemotohead ()
Date: June 08, 2015 03:23PM

Matt, if you use RTV there you need to be slapped!spinning smiley sticking its tongue out





Email me at: Dave Motohead

1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: Paulsgt ()
Date: June 08, 2015 03:44PM

Great Tip!!! thumbs up
Thanks Dave.

I've run across carbs that have mis-matched venturi clusters as well.

Paul Sergeant
CORSA Central Division Director / CORSA Treasurer <-new title
Lee's Summit, MO
CORSA since 1975
Member – HACOA, Corvair Minnesota, CORSA, Little Indians, POCI



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Re: Often overlooked on a carburetor rebuild...tip
Posted by: jjohnsonjo ()
Date: June 08, 2015 03:51PM

I use the exact same process for the YH accelerator pump cover, for the same reason.

Thanks Dave

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: Often overlooked on a carburetor rebuild...tip
Posted by: jimmyo ()
Date: June 08, 2015 07:36PM

Nice!

Jim O'Connor
45 miles north of The Bronx, N.Y.
1962 Greenbrier 110 4spd
1964 Monza Convertible 110 PG
"Wherever you go....There you are"

 photo 045ef0c8-2087-4eac-8a5d-9aa0d575d5e0_zps9946d378.jpg
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Re: Often overlooked on a carburetor rebuild...tip
Posted by: gerg ()
Date: June 08, 2015 07:44PM

GClass works great as a surface to mill on. I used this process to surface VW oil pump bodies to get a zero clearance (without a gasket) fear face to pump cover. Then the gasket thickness becomes the clearance between the gear faces and pump cover.

Great tip! I certainly didn't check this on my carb rebuilds. Will now!

gerg
Monroe, LA


1965 500 Coupe, 140hp / PG, Brown EFI - work in progress
1962 Rampside, 110Hp, factory 4 speed & 3.89 posi


Current cars and other fun stuff -> [gregblakeney.smugmug.com]

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: veverlove ()
Date: June 08, 2015 07:50PM

Something I've never done to a venturi cluster, but I always check the carb halves for flatness. Don't know why I never considered that part? Thanks Dave.

'65 Monza Convertible, 4-speed to PG conversion in progress
'02 Blazer 2DR, lowered for easier access & dog transport

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: Spectre ()
Date: June 09, 2015 04:28AM

Great tip...also useful for the Corvair oil pump cover.

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

Oklahoma City, OK

Click for Oklahoma City, Oklahoma Forecast

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: quorvair ()
Date: June 09, 2015 05:06AM

Thanks for sharing Dave...

I'm not familiar with carb rebuilding, so I got Bob Helt's carb rebuilding book & with this tip, I will try to rebuild a pair as a winter project next year.

Daniel Vallée
1961 Rampside 140PG
Salaberry-de-Valleyfield, Québec, CANADA

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: UGLYTRUK ()
Date: June 09, 2015 08:21PM

The mix-miss-matched parts I've seen in 'Vair cabs makes me think of a cheap used car with 4 mis-matched tires...

and does Dave sell these perfect rebuilt carbs???

I need one for my '64 Spyder, a YH of course!

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: upnorth1 ()
Date: June 09, 2015 09:15PM

nice, thank you

Chaplain Bob
135 miles from Canada

AT THE TIP OF LAKE SUPERIOR
1961 Loadside 95hp. 30 over bored and stroked. 145 block, 165 heads 4 speed
1966 Corsa clone 140 4 speed, 30 over.
1966 4 door 110 pg soon to return to factory 140 PG

DON'T mess with Old Men, we didn't get old by being, STUPID!!!

\/ this is a half mile from my house... \/

Click for Hermantown, Minnesota Forecast

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: cad-kid ()
Date: June 10, 2015 07:26AM

thumbs upGood tipthumbs up

Jeremy (cad-kid)
Kronenwetter, WI (Central Wisconsin)
CORSA Member#031129
SOLD-9-2016 65 Monza 4spd/140
My 65 Monza thread
My YouTube page yawning smiley

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Re: Often overlooked on a carburetor rebuild...tip
Posted by: corventure Dave ()
Date: June 10, 2015 07:45AM

To answer Andrew... No.. I don't sell rebuilt carbs! Far too busy with the other Corvair hobby stuff I do.

Corventure Dave

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