How to Synchronize Secondary Carbs in the Corvair 140 Hp Corsa Motor

Updated on January 17, 2019
perrya profile image

Perrya knows a fair amount about the Corvair, America's aluminum-engine classic car.

Primary Carbs are identified by the small vacuum advance.
Primary Carbs are identified by the small vacuum advance.

The 140Hp engine has four carbs. The major differences between it and the 110 Hp (two carbs) is that the 140 Hp uses a different cam, it produces different torque, and the engine heads are different.

Unlike the 110 Hp, where you have two primary carbs only, the 140Hp has two primary and two secondary carbs. The primary carbs control the secondary ones, which provide more power around 40+ mph; below that speed, you are operating with only two primary carbs. The 140 engine is usually found in a Corsa or a 1967-69 Monza. The Corsa was only made in 65-66.

The secondary carbs are slightly different as they have no idle mixture screw and some have no accelerator springs inside. But the Venturi cluster and jets still need to be free of clogging. There is a lockout lever on the side which is operated by the primary carb chokes. Before any secondary synchronizing can be done, you must have the primary carbs synchronized and adjusted correctly so both throttle plates in the bottom of the carb open and close at the same time, as do their choke plates ( located at the top of the carb), otherwise, synching the secondaries is a waste of time. The secondary carbs have a Lock-out lever that prevents the carbs from activating during warm up.

Assuming the primary carbs are in synch:

  1. Disconnect choke rods.
  2. Open the left primary choke valve to full vertical position. Use a .160” feeler gauge and measure the gap between the the lockout lever and lockout tang. It should be .160”. Bend to adjust if out of spec. Do this to the right side primary and secondary also.
  3. Hold choke valve closed and actuate the accelerator cross shaft to set fast idle cam. Turn and pull choke rod up until travel stops and adjust rod until bottom of rod is even with top of hole in choke lever. Connect choke rod and repeat operation on other choke.
  4. Disconnect the left and right secondary carb actuating rods, hold carb cross-shaft so primary carbs are in full throttle open (throttle plates are in vertical position).
  5. Make sure the choke valves are closed (secondary throttles are locked out). Adjust secondary carb actuating rod so its spring is fully compressed and clevis will just enter hole in cross-shaft lever. Now, back off counterclockwise, 2-3 turns. Repeat this on the other actuating rod.
  6. Connect both secondary actuating rods and with both choke valves wide open (vertical position), rotate carb cross-shaft to full throttle (plate is vertical), verify that all carbs reach vertical position (full throttle) simultaneously. If not, continue to adjust and tweek.
  7. With choke valves closed, rotate carb cross-shaft to full throttle and check primary carbs. Verify they reach position simultaneously. Verify that the secondary carbs are locked out and the actuating springs are fully compressed.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.


    0 of 8192 characters used
    Post Comment
    • profile image


      10 years ago

      i have a 1993 corsa, and it keeps cutting out everytime im stop, the car can be out of gear and my foot on the clutch but it still happen. do you have any ideas what the problem can be?? thanks


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)