Need Help Diagnosing Hesitation in 2-3 Gear

[BC1964]

New Corvair owner needs help. I just bought a 1964 Monza 900 Convertible (95 HP, 4-speed) and have been driving it to and from work a couple times a week for the past month which is about 6 miles roundtrip. The car has 94,000 miles on it (or 194,000) Generally runs pretty good, but am sometimes getting “hesitation” or "bucking" in 2nd and 3rd gear usually after the car warms up. Only happens about 30 percent of the time and usually goes away with a few gear shifts. Am running 89 octane non-ethanol gas, and don’t think the engine is back firing or pinging. More like a hesitation or fuel delivery issue. Also, the car will (about 5 percent of the time) completely stall while at speed (not safe), but starts right back up with a turn of the key. The car idles very well except for the problems noted above. This is my first classic car and I have almost NO mechanical knowledge or experience so pardon the layperson language. I also don’t have any history on the car that I bought on consignment with no books and records. My everyday mechanic that I consider generally skilled looked the car over, changed the oil, and gave the car a 7 out of 10 in terms of condition. But I’m not sure how much classic car experience he has. I do have a “classic car” mechanic that I am about to meet with to try to resolve the hesitation problem. Any insights from this board would be very much appreciated. I’ve been reading this board daily and it makes having a Corvair even more enjoyable. I’ve read a lot about syncing the carburetors but don’t enough to know if that’s the problem? I’ve tried to be as descriptive as possible with this post, but welcome any questions. Thanks for any help.

[91blaze]

Try running premium and advancing the timing a little. My car did the same when I first started driving it because I tried running regular unleaded like you are now. Theses cars run fairly high compression and usually require higher octane gas.

Be careful you don't advance too much because it is very easy to make them ping.

[bbodie52]

Welcome to the Corvair Forum!

Since your problem is intermittent, occurs unpredictably, and sometimes even kills the engine, I would guess that there is a possibility that the special breaker plate wire that connects between the ignition points and the negative terminal of the coil may be faulty. Whenever the vacuum advance is active, it physically moves the breaker plate several degrees to advance the ignition timing. This is normal operation, but in doing so it flexes the wire each time the breaker plate is rotated. This continual flexing can eventually fatigue the wire strands within the insulated lead and possibly cause them to break over time. If this has occurred inside the wire the wire may look to be perfectly intact externally, because the plastic insulation will look OK. But the wire strands inside may be broken and therefore making intermittent contact between the ignition points and the ignition coil.

Other possibilities might include a failing ignition coil, that is breaking down internally due to heat buildup, or a faulty condenser in the distributor. The condenser acts as dampener, preventing current from arcing (jumping) across the open gap in the breaker points, ensuring that the circuit is broken cleanly. A faulty condenser can be breaking down and causing premature wear of the ignition points, or intermittent ignition system failure.

All of this assumes that your distributor has not been modified to eliminate the points and condenser — replacing them with an electronic ignition system.

The intermittent nature of the fault in your car makes troubleshooting and fault isolation a little bit of a guessing game, with some trial and error experimentation necessary to ultimately locate the cause of your troubles. Another possibility might be the large 8-pin plastic multi-connector in the left-front portion of your engine compartment. These multi-wire connectors have eight wire connectors inside. They are exposed to vibration, heat, and moisture that can cause poor or intermittent contact internally as the internal metal contacts get corroded, dirty, bent or loose.

In the wiring diagram below, the wire that brings voltage to the engine compartment from the ignition switch (in the ON position) is labeled 18B (18 gauge Black). On the other side of the multi-connector the wire changes to a special resistor wire labeled 20 B/P (20 gauge Black with Pink Stripe). It continues on to a 2-pin multi-connector that comes from the starter solenoid, where it is spliced to a 20 B/Y (20 gauge Black with Yellow Stripe) wire that continues on to the ignition coil positive terminal. The purpose of this last connection is to provide the coil with a full 12 VDC power when the starter switch is engaged, and to then revert back to a lower 7 VDC through the resistor wire during normal operation after the engine starts. The higher cranking voltage promotes engine starting with a "hotter" spark plug voltage, and then prolongs ignition point life with a lower voltage during normal engine operation.

Getting back to the 8-pin multi-connector, it is possible that loose, dirty or corroded contacts inside the connector could be causing an intermittent operation as vibration causes power to the coil to be interrupted. You could try separating the two halves of the connector and inspecting/cleaning the metal contacts inside. Often just opening and reconnecting the multi-connector will improve the contact between the two halves, and may resolve your problem with intermittent ignition operation while driving.

This is in a different model year, and wire color codes may be different from your 1964 model year.

http://www.corvair.com/user-cgi/catalog ... IN&page=77

Part number C530: 60-69 DISTRIBUTOR POINT LEAD

Weight: 0 lbs 2 oz
Catalog Pages(s): 75,77(11«),77(19)
Price: $ 6.90


Common and Useful Corvair Websites

Corvair Forum viewtopic.php?f=225&t=6007

Any of the above possibilities may clear your ignition problem. You might start with the multi-connector, because it costs nothing to separate the two halves, inspect the contacts, and then reconnect the two halves to see if there is an improvement. You could then move on to the distributor and perform an ignition tune-up — replacing the points and condenser, inspecting and possibly replacing the distributor point lead, and possibly replacing the old coil with a new coil.

A popular upgrade is to eliminate the points and condenser, and the distributor point lead completely and to replace the components with an electronic ignition system. I prefer the Crane Cams system shown below, which eliminates the internal distributor electrical components and replaces them with an electronic switching system that utilizes an optical trigger system. This provides a more-reliable ignition system and eliminates the ignition points completely. The result is a more-reliable ignition system and no need for periodic ignition tune-ups. The coil upgrade is optional, unless your old ignition coil is faulty.

http://www.corvair.com/user-cgi/catalog ... IN&page=74

Part number C2851: ELECTRONIC IGNITION-62-69 ONLY*MUST HAVE CORVAIR ENGINE HARNESS OR COIL WITH RESISTOR

Weight: 2 lbs 0 oz
Catalog Pages(s): 74,OT,21
Price: $ 112.80


Part number C8391: CRANE HIGH OUTPUT COIL-45,000 VOLTS THEY DO NOT NEED TO USE THE RESISTOR INCLUDED

Weight: 1 lbs 12 oz
Catalog Pages(s): 75
Price: $ 59.90

I would like to encourage you to expand on your initial post and tell us more about yourself, your Corvair, and your goals for your Corvair. 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 and your Corvair will help us to write comments to you that are tailored to your needs and experience. Pictures are great too, because pictures of your Corvair will help us to visualize where you are with your Corvair and its condition at the present time. Knowing your location is also useful, because knowing where you live can sometimes suggest possibilities to resolve some issues or problems.

Corvairs appeal to the DIY "shade tree mechanic" who wants to learn to do repairs and maintenance. They are relatively easy to master and learn, using the Corvair Forum, factory shop manuals, and possibly help from a local CORSA (Corvair Society of America) club chapter, if one is available near you. Corvair-knowledgeable mechanics are rare, and when driving a 51 year old car there is a certain advantage to carrying a spares kit, some tools, and a shop manual in the trunk so that you are somewhat prepared to deal with a roadside breakdown. The pride of ownership and sense of accomplishment is often increased when you are willing to tackle your own maintenance of this classic car. My parents bought their first new Corvair in 1961 (I was eight years old) and I taught myself to overhaul a Corvair engine and automatic transmission in 1969 during my summer high school vacation. I had tools, a garage to work in, and a shop manual. At the time I could not dream of having the Internet, websites like the Corvair Forum, outstanding parts suppliers like Clark's Corvair Parts, or clubs like local CORSA chapters to help me along. But they are available now, and if you are willing you can certainly learn to work on your own Corvair!

[flat6_musik]

I'm thinking ignition~electrical problem. You've got to make sure there aren't any loose connectors or terminals that could be giving an intermittent voltage signal to the coil. Could also be a sloppy, worn distributor (although I doubt it). Brad was mentioning a definite possibility, that the points' pigtail wire is worn/broken......it actually happened to me, and that took me a while to figure out! Sometimes that wire's insulation will break open and ground out on the distributor body, where the wire passes through.

I've also seen the point gap change substantially when the distributor breaker plate moved (when the vacuum advance pulls on it to move it). Another reason I'd just rather disconnect the vacuum advance and bump up the initial timing to compensate.

[64powerglide]

Look for an inline fuel filter that could be clogging up then when the engine stops the sediment settles back down & it starts back up. Even the fuel tank sending unit screen can get sediment plugging it up. This would only happen if the car sat for a long period of time & now has gunk in tank. Been there done that.

[BC1964]

Thanks for all of the useful information and for taking the time to post it. That will help a lot. My class car mechanic/restorer stopped by to assess the car before I drive it to his shop. He noticed that the generator is arching a spark almost to the point of the spark coming outside the generator housing (not safe) when he manually throttled the car. He said that he would look into that and could rebuild the generator as needed. I also see Clark’s offers rebuilt generators for about $330. He thought my hesitation problem was probably related to something other than the generator, and I will have him look into the potential fixes already mentioned. If the generator arching gives anyone any additional ideas, let me know. I’ve attached a picture of the car. Thanks again. When we figure out the solution, will post that information.

[hentysnr]

Hi there
Welcome to the forum , I can assure you there is plentiful good advise available on the forum, an awesome bunch of guys. Well done with that beautiful car, you have an absolute beaut, love the colour, really hope you enjoy your Corvair as much as we do ours .

[bbodie52]

...He noticed that the generator is arching a spark almost to the point of the spark coming outside the generator housing (not safe) when he manually throttled the car...

I don't know if the information below would apply to your charging system problem. If you ever had your electrical system disconnected, it should have been polarized when reconnected to ensure the proper configuration of your charging system. The manual mentions the possibility of arcing and burning contacts if this is not done, but I don't know if that arcing would be visible in the generator, or would only occur in the voltage regulator.

Whenever the battery is disconnected from the vehicle for any reason the polarization procedure should be performed.

1960-1964 Corvairs used generators in their charging systems. These generators were replaced with charging systems using alternators in 1965-1969 Corvairs. Generators often needed to be polarized when the battery was disconnected or the generator was disconnected and removed or reinstalled to get it properly functioning again.

The shop manual states that if the system is not properly polarized a reversed polarity can cause arcing and burning of the contact points. This is something that is unique to generator-based charging systems, and is not applicable to alternators.





As shown in this illustration from page 8-6 of the 1961 Corvair shop manual, the center voltage regulator GENERATOR terminal is directly wired to the Armature terminal on the generator. The Field terminal on the regulator is wired to the generator FIELD terminal. The charging voltage output from the generator emanates from the generator Armature via the heavier 14Gauge wire.

When polarizing the generator, the temporary connection must be made between the BATTERY terminal on the Voltage Regulator to the GENERATOR (Armature) terminal.



If the generator has failed, you might want to consider a conversion to an alternator at this time, rather than spend money on a rebuilt generator and possibly on a new voltage regulator. Such a modification is a common upgrade in EM Corvairs. It requires changing the oil filter/generator adapter to provide a proper mount, and removing the old charging system and replacing it with a new alternator. Many suitable alternators have an internal integrated electronic voltage regulator, which can simplify the upgrade by eliminating the old external voltage regulator configuration. If you would consider such a modification, now would be the time.

A conversion from a generator to an alternator in 1960-1964 Corvairs is often a topic of conversation and sometimes confusion. I have located some good material on this subject, and have compiled it here. Hopefully this information will be of some help.

There are several options in the conversion:

• Use an externally regulated 10DN Delco alternator, as seen on late model 1965-69 Corvairs.
• Use an internally regulated 10SI or 12SI Delco alternator off a slightly later GM product.
• A true one wire setup. Here a special self exciting regulator is installed in a 10SI style alternator. Control of the dash idiot light is lost if this is used.
  
  The explanation shown below, along with its website link, seems to be one of the best explanations I've seen seen that describes some of the Delco alternator options available that could be fitted to a Corvair. (Keep in-mind the reverse rotation of the Corvair engine, which does not affect the alternator charging system but must be considered when fitting a cooling fan and pulley to the alternator — since the cooling fans are designed to rotate either clockwise or counter-clockwise. Proper air circulation is important for cooling an alternator).
  
  A standard Corvair alternator output capacity:
  • Alternator P/N: 1100639 — 35 Amps
  • Alternator P/N: 1100698 — 45 Amps

Greater charging capacities might be considered if the Corvair is fitted with special high-current, high intensity headlamps, some form of electric heater, or a custom sound system with external amplifiers supporting a special speaker configuration with subwoofer(s).

An alternator with an internal electronic voltage regulator makes good use of the increased reliability of a solid-state voltage regulator to replace the 1960s vintage external electro-mechanical voltage regulator. However, a switch to a single-wire alternator instead of a 3-wire alternator cannot be justified, and is not desirable in my opinion. The reasons are clearly described below...

Alternator Conversion
Selecting a Delco SI-Series Alternator

[url]http://bob_skelly.home.comcast.net/~bob_skelly/alternator_conversion/wiring_alternator1.html[/url]



To replace an EM generator with an alternator, the oil filter and generator mount adaptor must be replaced with the oil filter and alternator mount adaptor found on 1965-1969 Corvair engines. These used adaptors can usually be obtained from sources on eBay or from sources like the Corvair Ranch in Gettysburg, Pennsylvania...


http://www.corvairranch.com/

Suitable alternators can be sourced from normal Corvair suppliers, auto parts suppliers, eBay, local automotive junk yards, etc.

This link provides some additional information on the CCW rotation alternator fan and proper cooling for a high-capacity alternator mounted on a Corvair engine...


http://corvaircenter.com/phorum/read.ph ... 130,612166

More information on fitting newer-design Delco alternators to Corvairs...

http://www.unm.edu/~geoffj/Vair/Alternator.html

http://www.corvair.com/user-cgi/catalog ... N&page=84A