Revisiting the topic for a newbie - - - HIGH IDLE SPEED

[steve57]

They may be backwards but work fine. The problem on your carb is the part the rod is attached to is installed incorrectly. Look at the other pictures for correct installation.

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[stumpy]

THANKS steve57 after looking closely at the photos in and on the Helt book and those in the Shop Manual, I disassembled the right carb and tried to place the link on the back side of the assembly. I, had indeed, placed the "tripper" incorrectly on the shaft which is why the link was only able to be put on the outside. I find it interesting that the link is on the inside in the Helt book . . but in some published materials it's on the outside?!

Much like my wiring issue of late, various diagrams, photos and descriptions may show a "typical" situation but the reality of what is seen on a particular "original" vehicle may differ widely?! Last week, while installing my new electric fuel pump, I found both variations in wire colors and number of wires in the multi-connector in my engine bay as opposed to what is shown in my '65 Shop Manual, '66 Supplement and my aftermarket "color" wiring diagrams. All VERY HELPFUL to a guy who likes things to be laid out and consistent to published data!!

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Today has turned from the beautiful sunshine, blue skies and 78 degrees of yesterday to cloudy, gray and 42 degrees today . . . springtime in Texas. So, I will, yet again, remove the carbs and run through all of the exterior setup today. Will be back with the results . . . .

[bbodie52]

There is a 12-position multi connector in all 1965-1969 Corvairs. The Corsa uses more of the wire connectors than the Monza or 500, because of the tachometer in the Corsa and some of the other variations in assembly line production. The technical writers and engineers attempted to draw one single wiring schematic that "covered all the bases" for Corsa and Monza/500 production, but this sometimes adds to the confusion factor.

A replacement used engine compartment wiring harness that may be installed some decades later from a later-model donor car may permit correct electrical connectivity, but may also substitute a different wire color code or may have extra, unused wires that are not an exact match to an earlier model year. (Often called a "suitable substitute").

[stumpy]

Monday evening UPDATE . . .

Today, I removed both carbs, removed the outer lever, choke kick lever & connecting link and replaced them with the link now on the inside. Once again I reset all adjustments to spec, reinstalled carbs, replaced cross shaft & throttle linkages, connected fuel lines and primed carbs with my syringe. When I started the engine and walked to the back with my digital rpm gauge the motor seemed to be running in high rpm . . 3300 was the reading!! I shut her down, checked the accelerator linkage and decided to back off a little on the threaded cross shaft spring connector. Started again . . same result?!

After another afternoon reworking the carbs to specifications . . I now have a starting idle speed TWICE what it had been?! WHAT AM I MISSING HERE??

A couple photos from today . . . taken after the two minutes of running time:

[steve57]

I still say your throttle valves are not closing all the way. Detach the non standard throttle rods to cross shaft , back off idle screws, hold the chokes open and make sure the throttle valves close completely. Adjust links to fit. if you can’t adjust them get some original ones.

[bbodie52]

This may be right. A bent shaft or slightly misaligned throttle plate could prevent the throttle from fully closing — even if it has been fully released by the choke fast idle and throttle idle adjustment screw.

NOTE: THE TWO THROTTLE BUTTERFLY INSTALLATION SCREW THREADS ARE STAKED (INTENTIONALLY DAMAGED) AT THE FACTORY TO PREVENT VIBRATION FROM LOOSENING THEM. Cutting or filing the exposed threads may be necessary to fully remove the screws. If the throttle plate simply needs to have the position adjusted slightly, it may be possible to loosen them a small amount with a screwdriver to permit the plate position to be adjusted enough to permit the throttle to fully close. If the throttle shaft is bent or worn and needs to be replaced, the screws would have to be removed and new screws would have to be purchased and then restaked when installed.

Corvair Carburetor Bottom View

Screws – Throttle Plate: Must be replaced and "peened" over (file off "peened" end of old screw to remove)
https://ssl.corvair.com/user-cgi/catalo ... ow_page=56


Carb Throttle Return Spring (exc. Turbo) – Our regular carb return springs (page 58) help the accelerator linkage & carbs return to the closed position, but due to linkage wear & looseness, the carbs do not always return to a fully closed position. These 4 oz. springs are easy to install on all 1960–69 primary carb shafts & help the carbs return to fully closed. You will not notice an increased pressure at the accelerator pedal. If the main carb return spring should ever break.

NOTE: I have never tried these helper springs, so I don't know how effective they are.

Part number C1916: RETURN SPRING-CARB THROTTLE-60-69 PRIMARY-EXC TURBO-SOLD EACH

Weight: 0 lbs 2 oz
Catalog Page(s): 56
Price:
1 - 3 $ 4.95


https://ssl.corvair.com/user-cgi/catalo ... ow_page=58

[stumpy]

The Tuesday News Report . . .

Using a flashlight, I looked down the carburetor throats and it appeared that the left side was not closing all the way? Removed the left carb and checked the throttle plate, it just did not look like it was as closed as the right carb? Because I had installed new throttle plate shafts and the spring loaded O-ring shaft seals, the only "rebuilt" carb pieces reused were the plates. I removed the plate and rummaging in the "spares" box that came with the car, I removed the throttle plate from one of the original carbs, cleaned it up and installed it. It fit better and closed the small gap seen with the "newly rebuilt" carb that came on the car. I then started fresh on the setting procedures and checked and reworked all the settings. I also removed the linkage swivel rods and replaced them with the linkage rods that I had found on the original carbs.

Things are looking up . . a little. After about 3 - 4 minutes of warm up at 1840 - 1927 rpm, the idle settled down to a varying rate of 1250 to 1320. After about 3 minutes I removed the cross shaft linkage return spring and removed the threaded pin (which connects to the accelerator rod) from the linkage, essentially removing the accelerator from the equation. This lowered the rpm to 1130 - 1220. Ran the motor for another 10 minutes like this, checking the rpm every minute or so. 1108 to 1185 was the range while I applied throttle by hand and then let off. Not having even been around a Corvair since about 1963, I was a little wary of the slow idling down after I would return the linkage to the "rest" position?

Overall, today was better than the past few but I cannot see getting down to 600 - 650?!

After letting the car sit for 15 minutes, I decided to recheck the timing. It had moved up to about 16 - 18 degrees so I turned the distributor until i got 13 - 14 degrees consistently. Rechecking with the gauge I found the rpm to be 1170 to 1208.

So, better . . . but nowhere near any of the published numbers.

[bbodie52]

Make sure those throttle plate attachment screws are "staked" to distort the exposed threads and prevent the screws from vibrating loose and being sucked down the intake into a collision with a valve or piston!

Corvairs do actually idle at the specified engine speeds. You may have multiple problems that are preventing this from happening, and it may take some time to find them all, but persistence will hopefully pay off!

[Martin]

Hey,

I just stumbled upon your problem with the incorrect tripper installation. My carb looks exactly like your "incorrect" assembly. However, I cannot see a difference between the correct and incorrect assemblies. Can you please state, what you changed and what the criteria are for correct assembly?

As far as I understood, the illustrations in the Helt book are wrong? Again, I cannot spot the difference to the manual...

Sorry for the (maybe stupid) questions, but I'm now questioning my own assembly.

Best,
Martin

[stumpy]

Hey Martin,

If you have the Bob Helts book the Photo 6-4 on page 74 shows the "correct" (??!!) way to assemble the linkage. In my early photo the upper piece was installed backwards so the link had to be on the outside instead of behind (toward the carb) and caused a couple issues.

The two photos below illustrate the assembly better than my description:

GOOD LUCK!!
Dennis

[RBohl]

I had installed a "rebuilt" primary carburetor on my '65 Corsa 140 HP motor. Several times when up-shifting at cruising speed (50-60mph) the throttle stuck wide open. I could only stop this dangerous situation by cutting the ignition, shifting to neutral, and glide to the side of the road. I checked the linkages and could not find anything obviously wrong. When I restarted the car everything worked normally until the throttle jammed again; it could be several days later. I eventually found that the rebuilder had installed the kicker backwards on its shaft and this caused the linkage to jam itself in the throttle mechanism. This is a small detail but could be life or death situation for an inexperienced driver.

[miatawnt2b]

Make sure where your throttle plate shafts pass through the carb body are not excessively worn. Any leak between the shaft and the carb body will cause high idle.

[Dennis66]

They stated at the beginning that the carbs had been rebuilt, however... Dennis

[66vairguy]

The Tuesday News Report . . .

Using a flashlight, I looked down the carburetor throats and it appeared that the left side was not closing all the way? Removed the left carb and checked the throttle plate, it just did not look like it was as closed as the right carb? Because I had installed new throttle plate shafts and the spring loaded O-ring shaft seals, the only "rebuilt" carb pieces reused were the plates.

I've had a couple folks with those "O" ring shaft kits experience sticking throttles. On one the local "mechanic" supposedly rebuilt the Corvair carburetor for a club member. Then the carburetor throttle would stick. The "mechanic" just dipped it and didn't fix the worn out throttle shaft. The carburetor had those lousy "O" rings on the shaft and the cleaner turned them to a sticky mess.

I installed a new throttle shaft for him and cleaned up the carburetor and it worked fine.

[miatawnt2b]

Any updates Stumpy?
I fight this just slightly as well, although it's not bad enough yet to rip into the carbs again. I can only get my RPM down as low as 850 on my 65 Corsa.
-J

[stumpy]

A few months ago I did get Ruby idling & running well after reworking the throttle shaft between the carbs and using a slightly stronger spring on the return. Re-setting the timing (again!) also helped quite a bit. She has been doing fine and am quite happy with her performance.