Northern Michigan '66 Monza

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tcwheels
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Northern Michigan '66 Monza

Post by tcwheels »

Discovering this forum is very exciting! I'm a member of Airforums for Airstream owners and it's been invaluable for advice and swapping adventure stories, so I look forward to enjoying this forum as well.

As a Motown kid, I've been a car guy all my life (starting with my Dad's 1966 Toronado, which he got in August of '65 through some secret GM connection) I've never spent the time to learn anything more than how to own, drive, and maintain them. Although I have slightly above average general mechanical skills - I used to rebuild electric motors including rewinding armature and fields - I've never done anything more extensive on cars than oil changes, replacing disc brake pads and installing shocks. I CAN follow drawings, instructions, and diagrams (and advice!)

My plan for my Corvair has three parts: Drive it, learn about it, and repair/upgrade it. Basically, create and maintain a "driver" quality car if I'm using that term correctly. I'm not completely retired but I have flexible work schedule so I have time to learn and work on my car. My goal is to do everything myself even if it takes longer and isn't done perfectly. My brain needs a new challenge to stay healthy and I believe this is it. I have a nice inside space to store and work on the Corvair.

The car itself:

1966 Monza Convertible with 140hp engine and PG transmission in Marina Blue with black interior and white top (not the original color top). Every part is present and intact although some parts of the car are rough. It was restored in the 80s but it was a mostly a surface job. I don't know how old any of the wearable parts are other than it has new 185/70R14 tires.

This is what I've observed about the car so far:

- Lots of front end harshness while driving (Bushings, shocks, other components?) but it tracks straight.
- Significant hesitation upon acceleration although slow and steady acceleration gets past the hesitation (Gas, fuel pump, carburetor timing?)
- Exhaust leak (noisy) at end on drivers side (Pipe connection fail, muffler bad?)
- Fuel gage not working (Fuse, sending unit?)
- Backup lights not working (Bulbs, fuses, switch?)
- Passenger seat sag (springs?)
- Blower fan not working (Fuse, motor, switch?)
- Heater cable not responding to adjustment (Cable stuck, vent flaps stuck?)
- Clock not working (Fuse, broken?) I do know this is a common problem!
- Some dash lights not working (Fuse, bulbs?)
- Original fuel pump missing, hole plugged (Is this a common mod? Where is the fuel pump likely relocated?)

I have joined CORSA and although there is no affiliated Corvair club up north I'm checking out the West Michigan Corvair Club based in Grand Rapids which is about 2.5 hours south of me.

Any thoughts or advice would be appreciated!

(I'll attach some pics via my phone, it's a lot easier!)
Jerry Whitt
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Re: Northern Michigan '66 Monza

Post by Jerry Whitt »

Welcome to the Forum. The hesitation has a number of possibilities.

1. Dwell is not set properly (number of degrees of crankshaft rotation while points are closed, also know as coil saturation time) Usually 30 degrees,
measured with a dwell meter.
2. Initial timing is off. Should be 18 degrees advance, with the vacuum advance disconnected.
3. Idle speed too low. In drive, foot on the brake, about 700 RPM would be about right.
4. Carburetors are not balanced. Special air flow meter is used to set primary carburetors to be about the same.
5. Improper accelerator pump squirt as gas pedal depressed.
6. Vacuum advance unit does not work.

After checking these items, let us know the findings. Lots of folks here like to help.
Jerry Whitt
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Retired
Hemet, Callifornia
65 Monza, purchased new
65 Corsa convertible
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bbodie52
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Re: Northern Michigan '66 Monza

Post by bbodie52 »

Do you still live in the Detroit area or someplace in northern Michigan? If you are near Detroit or Grand Rapids, there is a large, well-developed CORSA (Corvair Society of America) club chapter in the Detroit area, and another in western Michigan.

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Detroit Area Corvair Club (DACC) 5498 Duffield Road, Swartz Creek MI
:link: http://detroitcorvairs.com Email: corvairkid1963@aol.com

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West Michigan Corvair Club, 7769 Burlingame Ave SW, Byron Center, MI
The West Michigan Corvair Club is based in Grand Rapids, Michigan but we cover the western side of Michigan.

:link: http://www.corvair.org/chapters/chapter495/, Email: wmcc@corvair.org

In addition to looking to the Corvair Forum for guidance, I would strongly suggest you check out the nearest CORSA club chapter. They can provide guidance and support in ways that an Internet forum cannot. Together, both can be a huge help in providing you with the benefits of years of Corvair experience and knowledge. They can also advise you if you need a good local body shop, upholstery shop, etc. when those needs arise. The family-friendly social events also add a lot to your enjoyment of your Corvair as you meet like-minded Corvair enthusiasts and aficionados.

I would also suggest that you click on the link below and then click on "Edit Profile" to modify your personal Corvair Forum profile to include your nearest city location and general Corvair description information so that the desired personal info will appear in each of your posts. This can help others as they respond to your posts and questions.

:link: memberlist.php?mode=viewprofile&u=8025
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
tcwheels
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Re: Northern Michigan '66 Monza

Post by tcwheels »

Thanks for the info! I live in Traverse City, which is about 4.5 hours North of Detroit and 2.5 hours north of Grand Rapids. It’s also the home of Hagerty Insurance...
tcwheels
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Re: Northern Michigan '66 Monza

Post by tcwheels »

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1966 Monza Convertible 140hp PG
tcwheels
Posts: 21
Joined: Wed Nov 22, 2017 2:48 pm

Re: Northern Michigan '66 Monza

Post by tcwheels »

ImageImageImageImageImage


1966 Monza Convertible 140hp PG
tcwheels
Posts: 21
Joined: Wed Nov 22, 2017 2:48 pm

Re: Northern Michigan '66 Monza

Post by tcwheels »

Jerry Whitt wrote:Welcome to the Forum. The hesitation has a number of possibilities.

1. Dwell is not set properly (number of degrees of crankshaft rotation while points are closed, also know as coil saturation time) Usually 30 degrees,
measured with a dwell meter.
Jerry -

The car has a Pertronix Ignitor kit installed by P.O. Does this impact the need or ability to adjust dwell?



1966 Monza Convertible 140hp PG
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bbodie52
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Re: Northern Michigan '66 Monza

Post by bbodie52 »

Adjusting the dwell is an ignition points gap issue associated with the number of degrees of rotation that the points remain closed (building a magnetic field in the ignition coil primary winding). The period, measured in degrees of cam rotation, during which the contact points remain closed is called the dwell angle.The dwell angle is changed by moving the points closer to or away from the distributor cam. The points gap (dwell angle) changes as the ignition points wear, so they need to be adjusted and/or replaced periodically. A change in dwell angle also impacts the ignition timing.

An electronic breakerless ignition system eliminates physical ignition points (a mechanical switch) and replaces that switching action with a transistor circuit to control charge and discharge of the ignition coil. The charging cycle time is electronically controlled and designed into the electronic ignition system. The trigger is a magnetic (Pertronix) or optical (Crane Cams) sensor, with no direct physical contact with the distributor cam.

The Pertronix Ignitor I unit has an issue with failure if the ignition key is left on for long periods of time without the engine running. The Pertronix Ignitor II has a problem with properly controlling the ignition coil firing when used on a Powerglide-equipped Corvair because of the slower idle speed with the car in gear and the idling engine loaded by the torque converter.

:link: http://www.corvair.com/user-cgi/catalog ... IN&page=74
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The Pertronix and Crane Cams breakerless ignition systems have been in use in Corvairs and other vehicles for decades. Recently a complete replacement distributor, using a magnetic pulse trigger, has been introduced on the market. I believe this system is a better choice than rebuilding and modifying the approximately half-century old Corvair distributor...

:link: https://www.perfvair.com/stinger-ignition-distributors/
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The Crane Cams optical control system seems to have a good reputation for reliability. I would prefer any of these options to ignition points.
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
tcwheels
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Re: Northern Michigan '66 Monza

Post by tcwheels »

So my idle is indeed way too fast. Kicks down to 1500 after being warmed up but that's as low as it will go. Double the recommended 700-800 RPMs

Am I correct in reading the advice given so far that the proper sequence is that I should check the possible electrical root causes before attempting to adjust the idle settings on the carburetors? If so, can I have the dummy's version of what how to check? Is there another symptom to look for if the Pertronix system has or is failing?

Thanks so much for your help, especially Jerry and and Brad!

- Darrell
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Re: Northern Michigan '66 Monza

Post by bbodie52 »

There is no simple, or compressed method to tune and troubleshoot a Corvair engine. A certain amount of knowledge or understanding is essential for the person doing the tuneup to interpret the results and then to be able to make logical adjustments accordingly. I would encourage you to do your homework, ask questions for clarification when needed. and follow the guidance below and in the shop manual to ultimately get the desired results with your Corvair.
bbodie52 wrote:Here is a fair amount of tune-up info, but if you can work your way through it the explanations may help with your understanding of how the various subsystems interact with each other, and why the proper sequence should be followed so you don't end up adjusting one area improperly to compensate for another area that isn't functioning properly.

:think: The dwell tachometer and timing light are the most common items thought of when working with an older engine in a classic car. As previously mentioned, however, there are ways to work around the lack of these tools. Adjusting the ignition points gap with a flat feeler gauge is a substitute for having a dwell tachometer. Setting the dwell with an electronic instrument is more accurate, however. The tachometer portion is needed to measure idle speeds and possibly to perform other tests where engine speed measurement is needed. It is possible to static-time your ignition system with a strip of paper placed between the ignition points. The engine timing mark can be manually positioned to the desired setting on the crankshaft pulley, and the distributor can be slowly rotated until the points just start to open and release the strip of paper. The distributor is then tightened and the mechanic has established an initial static timing setting. Of course, having a timing light makes things much easier, improves accuracy, and permits visual confirmation that the centrifugal advance is functioning. A vacuum gauge can be used for carburetor synchronization and other carburetor tests, and most vacuum gauges also double as a pressure gauge for measuring fuel pump output pressure. A UniSyn gauge, as shown below, measures airflow through each carburetor throat, and is an accurate way for synchronizing multiple carburetors at idle speeds and at partial throttle. A multimeter is a useful tool for troubleshooting and diagnosing electrical and charging system problems.

Many ignition systems in Corvairs have been upgraded by fitting an electronic ignition system to the distributor. These electronic ignition systems eliminate ignition points and condenser, which makes engine tuning somewhat easier and eliminates the need to periodically replace worn ignition points. The breakerless ignition system utilizes an optical or magnetic trigger to control the ignition coil. The system eliminates the need for a dwell meter or flat feeler gauge for ignition points adjustments. (A wire-type feeler gauge is needed for adjusting spark plug gaps). The tachometer portion of a dwell-tachometer, however, is still useful.

:think: Learning to work with the two Rochester primary carburetors on the Corvair really isn't all that difficult. But you should take the time to review the shop manuals and other attached manuals to get a better feel for what you are trying to accomplish. It is important to perform tuning steps in the right sequence, as outlined in the shop manuals and in the video below. Many of the tuning steps can impact the results found in other steps. There is a logical progression in tuning a Corvair engine, and skipping around or tuning components in a random order can only serve to confuse the outcome. The Delco Rochester service manual that I have attached is a good supplement to the Corvair shop manual. About half of the manual is dedicated to explaining the various subsystems and components of the Rochester HV carburetor. To some extent these carburetors perform as you would expect a computer-controlled fuel injection system and ignition system to operate — but they were designed at a time when computer-controlled systems that were designed to respond to sensor input throughout the car would only have been a dream. The various carburetor and ignition subsystems respond to engine temperature, engine speed, airflow and vacuum changes, etc. much like a modern engine — but without all of the sophisticated electronics and sensors. Engineers were attempting to accomplish the things we do now, but with much less sophistication — but still making changes as engine speed, throttle position, engine vacuum, and fluid and air flow characteristics varied. If you take the time to read through the Delco Rochester manual, you might come to understand how the choke system functions, what an accelerator pump does and why it exists, and how the distributor is designed to adjust timing at low engine speeds and at higher engine speeds using both a vacuum advance and a centrifugal advance to provide the correct timing at various engine speeds and load settings. A good understanding of how these systems work and what they are supposed to do can be a great help when tuning and troubleshooting your engine.

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: viewtopic.php?f=55&t=13170&p=90875#p90875


The entire shop manual and many other Corvair technical references can be downloaded at no cost using the following link...

Common and Useful Corvair Websites
:link: viewtopic.php?f=225&t=6007

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.
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: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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:link: viewtopic.php?f=55&t=13664&p=94537&hili ... nce#p94537
Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
tcwheels
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Re: Northern Michigan '66 Monza

Post by tcwheels »

Fantastic! Thanks so much for all the information and source material - now I'll get to work and study all of it!
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Re: Northern Michigan '66 Monza

Post by bbodie52 »

You did not state if you have a Pertronix Ignitor I or a Pertronix Ignitor II installed in your distributor. The Ignitor II has a known problem with the slow idle normally introduced in a Powerglide-equipped Corvair that slows engine idle under load. When the idle speed drops too low, the slow pulse rate seems to introduce errors in the Pertronix Ignitor II electronic module that causes misfiring of the ignition coil and a loss of some firing cylinders with associated stalling of the engine at an otherwise proper idle speed. (See NOTE 4 in the shop manual tune-up chart above). If you begin to get the idle speed down where it is supposed to be and you have a Pertronix Ignitor II installed, the problem described here with the Pertronix Ignitor II may surface and cause you problems. The Pertronix Ignitor I does not have this fault.

:link: http://www.pertronix.com/prod/ig/ignitor2/default.aspx
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Brad Bodie
Lake Chatuge, North Carolina
Image 1966 Corvair Corsa Convertible
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