Idle speed

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Jeff+Carrie'63
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Idle speed

Unread post by Jeff+Carrie'63 » Mon Nov 06, 2017 10:43 am

I just purchased my first Corvair - a 1963 Monza 900 (automatic). The last time I was in a Corvair, I was riding with my dad in his '62 Corvair when I was very small. I just drove it home from Indianapolis yesterday. It was a 120 mile trip and the car did very well. However, it seems the idle is running very high. But, again, I am not used to vintage cars and specifically Corvairs. When I stop, the car idles at a rate that it is wanting to push me and unless I keep my foot firmly on the brake, it will take off. I had to start putting the car in N when sitting at lights just to keep from having to exert full pressure on the brake. If you have any suggestions on what to check or perhaps this is normal with a Corvair, please advise. Thank you in advance for any assistance. (When it comes to mechanic work, I'm pretty green, but willing to learn.)

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bbodie52
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Re: Idle speed

Unread post by bbodie52 » Mon Nov 06, 2017 12:11 pm

:wave: :welcome2: Welcome to the Corvair Forum!

Based on your comments about your willingness to learn, I have posted a large amount of tuneup information below that is applicable to your Corvair. Note 4 in the tuneup chart below specifically addresses the adjustment of the final idle speed on a Corvair with a Powerglide automatic transmission. Adjusting the idle speed is a little different with the automatic transmission, because of the load placed on the engine by the torque converter (fluid coupling) when the transmission is in gear. The base idle speed in neutral has to be a little higher to compensate for the drag on the engine when the transmission is shifted to DRIVE or REVERSE.

The high idle speed you are experiencing can be caused by ignition timing issues, a carburetor throttle linkage that is binding somewhere in preventing the engine to return to the correct idle speed when you release the throttle, or possibly a carburetor synchronization issue. It is not uncommon to find an engine that has a problem with the idle circuit in one of the two carburetors. Sometimes an owner will incorrectly increase the idle speed of the one working carburetor to compensate for the lack of participation by the other carburetor. If that occurs the engine is idling on three cylinders and the improper adjustments that have been made to compensate can cause problems with excessive idle speed load on the transmission when the car is stopped.

Since you have just purchased the car and are not familiar with its maintenance history, I would suggest spending some time learning to tune the engine, as outlined in the two videos below. This will take you through a process of learning to adjust and verify each setting in the proper sequence to get the engine running properly. Many of the settings interact and impact other settings, so jumping in right in the middle in making an adjustment may in fact be compensating for another adjustment that is incorrect. It is important to perform all the tuneup steps in the proper sequence, and this is outlined fairly well in the Chevrolet training videos below. If you intend to do your own maintenance on your Corvair, learning to follow the shop manual procedures to fully tune the engine is a good way to start. If there are any technical problems with any of the engine components (such as a faulty carburetor or a sticking throttle linkage, or a vacuum leak, working your way through the tuneup procedures will also help you detect faults that may have to be repaired before a successful tuneup can be completed. If you lack necessary tools such as a timing light, dwell tachometer, vacuum gauge, or the optional but useful UniSyn gauge, now might be a good time to start building a basic set of tools to make your goals as a DIY "shade tree mechanic" possible.

What test equipment is required for older cars without computers
:link: http://www.corvairforum.com/forum/viewt ... ght#p92065

The links, videos, and attachments below should help you to understand how to work with a dual carburetor engine. Try not to be intimidated by two physically separated carburetors. They really function very much like a single two-barrel carburetor, but are physically separated from each other out of necessity due to the layout of the flat air cooled engine with cylinders opposed to each other. The Corvair engine layout is in many ways similar to many motorcycle engine configurations. It usually takes an experienced automobile mechanic a little adjustment time to get used to the way things are done on a motorcycle. The aluminum, air cooled flat six Corvair engine often is seen as a challenge to an automobile mechanic, who is not used to the "strange configuration" found in a Corvair.

:link: http://www.corvairforum.com/forum/viewt ... 875#p90875

Watching the video presentations below helps to provide insight and understanding about proper sequencing of the tuneup steps and procedures. Skipping around can insert obstacles and problems with getting the engine properly tuned.

The portion of the first video segment toward the end (Part 1, 5:10) and at the beginning of the second segment discusses throttle linkage adjustments and carburetor synchronization.

Tuning the Corvair Engine — Part 1



Tuning The Corvair Engine — Part 2


bbodie52 wrote:
flat6_musik wrote:...I bought a Uni-Syn and only used it once. It seemed to me that at idle, there was barely enough air flow to raise the ball. It pissed me off and I put it away...
The Uni-Syn Carburetor Balancing Instrument is a tool that I remember as far back as the 1950s and 1960s. It was designed for use in multi-carburetor automobiles, motorcycles, etc. that were initially common in European vehicles, but were later found in American vehicles like the Corvair.
Image :confused:
:idea: The Uni-Syn is an airflow gauge that must be calibrated to match the specific engine airflow moving through the carburetor throat. The flow control in the center of the Uni-Syn is mounted on a threaded pin. Rotating the flow control raises or lowers it, which increases/decreases the air gap, which impacts the air velocity passing the oriface that allows some airflow to pass through the gauge. With the Uni-Syn held firmly on the carburetor intake with the engine idling, the flow control is adjusted so that the plastic float is approximately centered in the glass sight tube. Once calibrated, the Uni-Syn can be moved back and forth between the two primary carburetors to compare airflow at idle. The goal is to play with the idle speed screws to get an even airflow level that matches between both carburetors, and at the same time produces the desired idle speed. Before fine-tuning this idle balance with a Uni-Syn, the ignition system, idle speed and idle mixture should have been adjusted following the standard procedures as described in the factory shop manual. The balancing step with the Uni-Syn gauge is added at the end of the tuning procedure to measure actual airflow though both carburetors at idle, and balancing that airflow using the airflow meter as a measuring tool, rather than simply relying on a physical balanced "calibration" using a strip of paper to detect initial contact between the idle speed adjustment screws and the carburetor linkage, followed by counting the screw turns needed to obtain the desired idle speed (and ensuring that the same number of screw turns are applied to each screw). That procedure achieves a fairly close initial setup. The use of the Uni-Syn airflow gauge as a final step ensures balance between the two carburetors by measuring actual airflow.

:wrench: Once the balanced idle airflow and desired idle speed have been achieved, a similar procedure can be used to synchronize the airflow when the carburetors are held open at a faster engine speed by the throttle linkage. Again, the shop manual procedure can be used to set the initial mechanical balance between the two sides of the throttle linkage. The linkage segment connecting the accelerator pedal to the cross-linkage between the two carburetors is temporarily disconnected, and a turnbuckle is temporarily attached to hold the throttle opened against the pull of the throttle return spring.
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The turnbuckle can be adjusted to hold the throttle open at approximately 1500 RPM. The Uni-Syn center flow control is readjusted to re-calibrate the float to a position somewhere in the center travel of the sight tube, based on the increased airflow through the carburetors at the higher steady RPM maintained by the turnbuckle arrangement. As with the idle synchronization procedure, the re-calibrated Uni-Syn is used to measure the airflow moving through the two carburetors. The goal is to fine-tune the threaded portion of the carburetor actuation linkage so that the same airflow reading is attained on each carburetor, but this time with the throttles held open by a pull on the throttle linkage, instead of by the setting of the idle speed screws. When the airflow has been balanced using the throttle linkage adjustment, the balancing procedure has been completed and the normal accelerator pedal throttle linkage can be reconnected.

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TIPS & CLARIFICATION...

With the engine at idle, you want to open the Uni-Syn flow control as much as possible, but still keep the float in the sight glass at about mid-level. Then check the other carburetor, which you want to read the same flow rate. You may have to adjust the flow control a few times as you adjust the carburetor settings. Just remember to check each carburetor with the flow control set at the same point, and to keep the sight glass in the vertical to prevent the float from hanging up in the tube.

The wheel in the Uni-Syn venturi controls the flow through the tube, or in other words how high the bead is in the cylinder for a given engine speed. You need enough flow to not strangle the engine, and the bead works just as well in the lower third (which still lets good air flow through). Make sure the idle speed doesn't drop when you place the tool on the carb: if it does, open it up.

Before setting the carbs, make sure that the ignition is right: points and timing set, good wires and plugs. Rich running is often blamed on carbs when in fact it's a weak, retarded spark. Check the throttle shafts: loose ones let in air and lean the mixture, raising idle speed, as well as throw off the linkage action. Check the linkage that connects the carburetors. if it's loose, one will open before the other. Make sure there are no vacuum leaks.

With a twin carburetor set up, disconnect the linkage that connects one carburetor to the other. Set the idle speed with the linkage screws first. Use the Uni-Syn to check that each carburetor is drawing equally at idle. This may take a few tries until you get both drawing equally at the speed you want. Blip the throttle to see if they come back to those settings (worn throttle shafts can fool you). Set the idle mixture screws in accordance with the shop manual instructions. Check the balance again. Hook the linkage back up. If one carburetor now draws more, adjust the linkage until it's back to roughly equal.

Once the carburetors are drawing equally at idle, hold an engine speed: at about 1500 RPM. This checks that the mechanical linkage is pulling equally. You'll need to open up the Uni-Syn center wheel to draw more air and bring the bead down in the tube. If both carburetors are within a bead's thickness of each other, that's good. If one is definitely off from the other, the higher flow carburetor's linkage is being pulled more than the other. You'll need to figure out why that's happening mechanically to rectify it. :chevy:
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The link below will provide you with a list of useful websites that are Corvair-related. Some of the links will lead you to an extensive technical library that will allow you to download shop manuals and other technical references in Adobe Reader (.pdf) format at no cost.

Common and Useful Corvair Websites

:link: http://www.corvairforum.com/forum/viewt ... 225&t=6007

:dontknow: I would like to encourage you to expand on your earlier post and tell us more about yourself. If you can describe your personal assessment of your mechanical skills and abilities, that would help a lot. Members of the Corvair Forum love to be helpful in assisting other Corvair owners with technical support and advice, but it helps a lot if we have some understanding of your technical background and mechanical abilities, Corvair-related knowledge, etc. Helping us to know more about you will help us to write comments to you that are tailored to your needs and experience. Knowing your specific location is also useful, because knowing where you live can sometimes suggest possibilities. If you can post some additional photographs of your Corvair engine compartment, trunk, etc. we would love to see more of it.

Please be sure to check back here on the Corvair Forum to let us know what you find as you work with your Corvair. Please feel free to ask questions here at any time if you are uncertain of how to proceed or how to interpret the results you are getting. Hopefully the final outcome will not only provide you with a Corvair that is running better than before, but it will also provide you with increased knowledge and self-confidence when working on your Corvair. As you develop your mechanical knowledge and skills you will be much better prepared to deal with the issues and problems that can surface when driving a classic vintage Corvair. Most modern mechanics do not know how to work with older cars, so reliance on professional mechanics to keep your car running properly can be difficult and could leave you stranded.

You did not state your location. The last website link listed above also includes a link that lists CORSA (Corvair Society of America) club chapters across the USA. If you find a CORSA club chapter near you, I would strongly suggest contacting them and attending a meeting to decide if you would benefit from joining the club chapter. Socializing with like-minded Corvair enthusiasts in the local area can help a lot as you learn about Corvair ownership.

:welcome:

:chevy:
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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Jeff+Carrie'63
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Re: Idle speed

Unread post by Jeff+Carrie'63 » Mon Nov 06, 2017 12:54 pm

Thanks so much, bbodie52! This is exactly what I need. I do indeed need to get some of those test tools. I'll look into those as well.
Really appreciate the help on this. Very green to Corvairs, but really looking forward to getting this one in show condition.
Thanks!
Jeff

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Jeff+Carrie'63
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Re: Idle speed

Unread post by Jeff+Carrie'63 » Mon Nov 06, 2017 1:12 pm

I'll add some photos as soon as I figure out how to do that. lol!
I am a novice, by any standards. I have worked on cars in the past, but only minor work like brakes, belts, some engine work and or course oil and filter changes. I did check out CORSA clubs near me and it looks like the one in Louisville, KY is the closest. I live in southern Indiana. I already have several questions, but will stick to one issue at a time. I really want the engine is great condition before everything else. The car is actually a great find, I think. It has been completely restored and the engine has been overhauled for the most part. It does use oil, but I understand that is part of owning a Corvair. :)

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1963 Corvair Monza Coupe - White on Red with Hands Wheels

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terribleted
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Re: Idle speed

Unread post by terribleted » Mon Nov 06, 2017 4:52 pm

Using oil is not part of owning a Corvair (depending on your frame of reference anyway...60's cars all used more oil than cars today. A quart in 2-3k miles is not unusual). A few leaks...that might be a different story, but when re-sealed well most cars will end up dry or close to it without going to any extremes.
Last edited by terribleted on Mon Nov 06, 2017 4:54 pm, edited 1 time in total.
Corvair guy since 1982. I have personally restored at least 20 Vairs, many of them restored ground up.
https://www.facebook.com/tedsautorestoration/

Located in Snellville, Georgia

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bbodie52
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Re: Idle speed

Unread post by bbodie52 » Mon Nov 06, 2017 4:54 pm

I added a couple of 1963 Corvair photos to your previous post so that you could edit that post and see how each image was embedded. There are two methods of embedding photographs, using uploaded embedded files from your PC or embedding a URL address from a selected photo that is hosted by a public access web page on the Internet. If you edit your post above you will see how they were embedded. Both methods are explained below...

Here is some material on posting pictures on the Corvair Forum. Please let me know if you have any questions...

:whoa: Photographs can be hosted on other public websites, and then shared here using the photograph image URL. Facebook is another URL source option. Alternately, individual photographs can be uploaded directly to the Corvair Forum from a computer hard drive, thumb drive, etc.

If you are not familiar with posting pictures on the Corvair Forum, here are some guidelines. I wrote these instructions a while ago to try to help new members of the Corvair Forum with posting pictures. There are two methods. Hopefully these guidelines will help you...

To be able to post pictures, always use POST REPLY — not QUICK REPLY — to open the full-featured editor.

There are basically two ways to post a digital photograph on the Corvair Forum. The first, illustrated below, involves inserting an image URL address between two Img markers. The URL image address is copied from an existing picture on the Internet. The source image can be another picture already on display within the Corvair Forum, or it can be just about any picture, artwork, or graphic image that is publicly viewable by anyone on the Internet. You simply need to copy the source image URL temporarily to the computer "clipboard", and the paste that URL address within the text you are writing on the Corvair Forum (between the two Img markers). Once you have posted your text, the Corvair Forum software will simply grab the image from the source URL and will display it embedded within your text (at the location where you embedded the Img markers and source URL).

For example, I am embedding the First Place Image and Avatar Image images to the left of this post within the text here by copying their URL addresses between two Img markers.

Here is what the above text looks like unsaved...
For example, I am embedding the First Place [img ]http://www.corvairforum.com/forum/image ... KPLATE.png[/img] and Avatar
[img ]http://www.corvairforum.com/forum/downl ... 285003.jpg[/img] images to the left of this post within the text here by copying their URL addresses between two Img markers.
Maybe this illustration will help...

You can manually copy images and pictures from other Corvair Forum posts that were embedded as uploads by right-clicking each image in the source with your right mouse button and selecting Copy image URL from the menu choices. Doing so will invisibly copy the image URL address to the computer temporary data buffer called a clipboard. Using the Img button at the top of the editor screen, and the standard PC copy and paste technique will allow you to paste that URL address data from the clipboard into your Corvair Forum text (surrounded by bracketed img markers), which will display as the original picture or image when the post has been saved for display. It illustration below depicts the process.

Click on image to enlarge for better viewing...
Corvair Forum Image Transfer.jpg
NOTE: This same technique will allow you to copy just about any graphic, photo, or other displayed image from any public website, Facebook, or other website that is not secured and is publically viewable by right-clicking the desired image, obtaining the image URL, and then pasting the URL with Img markers into your Corvair Forum text.

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The other method of embedding pictures involves uploading the images that you have physically stored on your computer. Simply scroll down in the editor where you will see Options and Attachments tabs. Click on the Attachments tab and then click on the Add files button. You can use the file manager to then navigate to desired photos on your local drives. You can select one file at a time to upload, or you can select multiple files in the same folder by holding down the Ctrl button on your keyboard while clicking on desired files with your mouse. When the file or files have been selected, click Open at the bottom of the file manager window to upload the file(s) to the Corvair Forum. When the uploaded file(s) are listed, you can use the Place inline buttons to embed the photo(s) in the desired locations by positioning your cursor first and then clicking on the Place inline button(s)

The embedded photos will become visible when you click on Preview or Submit. The pictures you upload will not be visible as photographs until you click on Preview or Submit.

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There is also an online help section on the Corvair Forum. See...

How to post a picture (and start a new topic)

CorvairForum Site Topics ‹ Site Specific Topics ‹ Site Features and How to Use Them ‹ How to post a picture (and start a new topic)

:link: http://www.corvairforum.com/forum/viewt ... =196&t=618
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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Jeff+Carrie'63
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Re: Idle speed

Unread post by Jeff+Carrie'63 » Tue Nov 07, 2017 7:24 am

I think I have a leak issue and need to get that resolved right away. It is burning some oil, but the leak is the issue. It appears to be a faulty seal.
Thanks!

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Jeff+Carrie'63
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Re: Idle speed

Unread post by Jeff+Carrie'63 » Tue Nov 07, 2017 7:38 am

19247577_10156059169828984_3479373652916468212_n (1).jpg
My 1963 Chevy Covair Monza 900. It was totally restored with all new interior and a new paint job in original cordovan brown.

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bbodie52
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Re: Idle speed

Unread post by bbodie52 » Tue Nov 07, 2017 8:55 am

Jeff+Carrie'63 wrote:Tue Nov 07, 2017 9:24 am

I think I have a leak issue and need to get that resolved right away. It is burning some oil, but the leak is the issue. It appears to be a faulty seal.
Where's the FAULTY SEAL???
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VITON.jpg
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Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible

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Jeff+Carrie'63
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Re: Idle speed

Unread post by Jeff+Carrie'63 » Tue Nov 07, 2017 9:11 am

:rolling:

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