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throttle linkage adjustment - 65 turbo
Posted by: jeffmort ()
Date: July 24, 2022 10:24PM

My car is a 1965 Corsa turbo (all stock). I am not getting any boost from my turbo and I am thinking my problem may be that my throttle linkage is not adjusted properly which is not allowing me to get to wide open throttle when my gas pedal is fully depressed.
My questions are:
1) How can I tell if/when my carb throttle plate if fully open when the carb is installed on the car?
2) Is the carb plate wide open when the the throttle lever mechanism on the carb is touching the throttle stop on the carb body?
3) Can I look inside the carb by removing the air cleaner, holding the choke plate open and then actually be able to see if the throttle plate is fully opening?
4) Is the throttle linkage adjusted properly when I press the gas pedal to the floor and both the linkage at the differential is against its stop at the same time the carb lever is at its stop against the carb body?
I have the throttle linkage adjustment procedures from the factory service manuals and plan to follow those procedures but first wanted to get answers to these general questions before I got started with the adjustment procedure.
Thanks in advance.
Jeff

Jeff
Encinitas, CA
1965 Corsa

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Re: throttle linkage adjustment - 65 turbo
Posted by: RobertC ()
Date: July 24, 2022 11:23PM

Need two people: one to press accelerator pedal to the floor and one to check the throttle plate in the carb.

Since you have had the car for a while, do we assume that the turbo generated boost previously?

There are many "moving pieces" in the accelerator linkage - that need to be in good shape. The shop manual should have diagram. Clark's Corvair's online catalog also has pictures.

Clark's Corvair (and others, I assume) sell a bushing kit.

Places to check:

Accelerator pedal - loose on rod; bracket that holds it to the floor is broken; not far enough off carpet

Rear tunnel - bell crank - worn / missing bushings; bolt that holds it in place rusted / loose - usually east coast cars.

Transmission - lever on shaft can come loose; worn / missing bushing

Adjustment at the carb is incorrect.

Accelerator rod from transmission to engine - rare, but some people get creative and bend it

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Re: throttle linkage adjustment - 65 turbo
Posted by: jeffmort ()
Date: July 24, 2022 11:41PM

Thanks for the info.
Car hasn't had boost since i have owned it - been trying to sort it out along with other issues for a while now.
What I have done:
1) All throttle linkage parts from pedal to carb have been refurbished, replaced, lubed, etc. - everything moves freely and happily.
2) Top of pedal is 3.1" from carpet.
3) I just had carb and turbo rebuilt by respected Corvair guy - I'm confident the guy did it right.
4) Distributor is working properly and had all the right parts
5) Fuel pressure regulator installed - set to 2.25 lbs.
6) New stock muffler installed, no exhaust leaks apparent.
7) Boost gauge tested - its works properly.
The car runs very well, just no boost.
My sense is that I am not getting wide open throttle.

My basic question for now is when I have someone press the pedal to the floor, how can tell if the throttle plate is fully open as the plate is inside the carb/throttle body and I cant see it?
What I can see is when the gas pedal is fully depressed, the carb lever at the throttle linkage is not reaching the stop on the carb body. Is this enough to tell me that I am not reaching wide open throttle?
Picture shown is with pedal pressed to floor

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Re: throttle linkage adjustment - 65 turbo
Posted by: RobertC ()
Date: July 25, 2022 12:08AM

You need to lean over until you look down the throat of the carb.

Not familiar with YH, but a small flashlight might help. Throttle plate should be horizontal.

Did you ever make contact with San Diego club? Knowledgeable people there.

Never owned a turbo Corvair - to test you need to find room to run - a steep hill would help, but you should get boost on the flats, too.

Need rpm to get boost. Put the car in second gear and run the engine up to 5000 rpm and I think you should get boost. Or, you can start from a dead stop in first gear and run it up.

Like I said, never owned one, but you should get boost from 3000 - 3500 rpm up.

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Re: throttle linkage adjustment - 65 turbo
Posted by: zarfnober ()
Date: July 25, 2022 04:19AM

Once you’ve confirmed your throttle plate opens completely, find a stretch of road and put your foot to the floor in 3rd gear and hold it there to at least 4500-5000 rpm, and 4th gear too. The stock turbo isn’t going to be making much boost until 3rd gear, and you really need to keep the pedal to the metal. Seriously , you’ve got to keep the revs up, and the throttle open, because once you back off the throttle, boost goes away.

Keep it floored all the way through 3rd and 4th gear, with engine completely warmed up, if still no boost you’ve likely got a turbo issue. Check and make sure there’s only one gasket between the exhaust housing and heat shield, and make sure the clamp is tight holding the exhaust housing to the center section. Two gaskets between the hsg and heat shield will make too much clearance between the turbine and hsg, a loose clamp might not compress the heat shield to the center section, not allowing the turbine to spin.

I wouldn’t worry so much about an exhaust leak, it takes a pretty bad exhaust leak to keep it from making boost, and you’ll hear it. Keep us posted.

Rocco

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Re: throttle linkage adjustment - 65 turbo
Posted by: steve c goodman ()
Date: July 25, 2022 05:31AM

When carb was off did you stick a finger into compressor housing and spin turbo wheel? Never use anything to help turn the wheel only your finger.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

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Re: throttle linkage adjustment - 65 turbo
Posted by: jeffmort ()
Date: July 25, 2022 08:59AM

Rocco-
I have run the car up to over 5000 RPM's and held it there (may attempts) as you have described (engine warm, 3rd gear, yup slight incline as well as flat, etc.) and get no boost.

Steve-
Yes I stuck my finger into compressor to spin the turbine wheel - the wheel spun smoothly. Wolf Industries (Grant) just fully rebuilt the turbo and tested it before returning it to me.

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Re: throttle linkage adjustment - 65 turbo
Posted by: playerpage ()
Date: July 25, 2022 10:15AM

Something I had to deal with was vacuum leaks and exhaust leaks. Have you checked that everything is tight between the turbo and the exhaust pipe, and then at the crossover underneath? Also if you take some carburetor cleaner and spray it around the edges of the carb, turbo, and where the intakes meet the heads while idling, if you get a loss or even a increase in power, that would mean that there's a leak in that area.

Eric C. Player
Fargo, North Dakota
MEMBER: CORSA National, Central Coast CORSA, South Coast CORSA, Vintage CORSA, Sfba CORSA, and Great Plains Corvair Club.
THEN: 1965 Monza 110, Canary Yellow - 1965 Corsa 180 Turbo, Red - 1966 Monza 110, Purple - 1967 Monza 140, Red - 1966 500 110, Black; nicknamed "Shadow" - 1965 Monza 110, Camaro Yellow; nicknamed "Silver"
NOW: 1966 Corsa 180 Turbo, Blue; nicknamed "Bluvair"
---------------------------------------
"He cautioned me not to take notes. It would not have helped if I had, as he would start a paragraph with, 'It is therefore obvious. . .'
and go on from there to matters which may have been obvious to him and God but to no one else."
-- Robert A. Heinlein, character of Daniel B. Davis, 'The Door Into Summer.'

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Re: throttle linkage adjustment - 65 turbo
Posted by: corvairsince70 ()
Date: July 25, 2022 11:41AM

If the tab on the throttle linkage is not hitting the stop on the carb, the throttle butterfly is not opening fully. This tab can be bent "slightly" to adjust for full throttle. Your problem my lie in the correct adjustment of the linkage from the cross shaft to the carb. Manual states this needs to be approximately 126 degrees. This is very important.

Dennis
Nashville area

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Re: throttle linkage adjustment - 65 turbo
Posted by: jeffmort ()
Date: July 25, 2022 12:30PM

Thanks. Ill go through adjustment procedure and see what happens.

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Re: throttle linkage adjustment - 65 turbo
Posted by: DOUG WARD ()
Date: July 25, 2022 09:01PM

Jeff, I had a similer problem with my '65 Corsa. I found that the small ( 1/8" OD) tubing that connects the gauge to the LH head was loose in it's connection. You might get a vacuum reading on the gauge but when the engine is making boost, it wants to blow that joint apart, loosing any boost signal. I suppose the same thing could happen at the tubing to gauge connection too.

Doug Ward
Orange, Calif.
65 Corsa 180, 64 Monza convertible, 61 Lakewood, 61 Monza





Edited 1 time(s). Last edit at 07/25/2022 09:04PM by DOUG WARD.

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Re: throttle linkage adjustment - 65 turbo
Posted by: jeffmort ()
Date: July 25, 2022 09:58PM

My gauge appears to be good. I disconnected it at the manifold and used my air compressor set to 15 lbs, stuck the air compressor nozzle in the disconnected vacuum line, pressed the air nozzle and the gauge read 15 lbs.
I did notice that the carburetor cross shaft was installed backwards so I flipped it around to the correct orientation and was able to get my linkage set up properly to achieve 126* at idle screw and throttle stop on carb at wide open so I think I now have my linkage set up properly to achieve WOT

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Re: throttle linkage adjustment - 65 turbo
Posted by: jjohnsonjo ()
Date: July 26, 2022 10:23AM

Try plugging the exhaust up with a potato, the engine should only idle for less than a minute if you don't have any exhaust leaks.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: throttle linkage adjustment - 65 turbo
Posted by: steve c goodman ()
Date: July 26, 2022 12:16PM

I don't have any potatoes hanging around so I roll up a couple of red shop rags and while engine is warm and at idle I stuff the rags into the exhaust outlet and hold in place with a hammer handle. As JO states, if engine is still running after a minute you are leaking exhaust.

best wishes, Steve
Rear Engine Spec. Inc. Golden, Colo.

1962 spyder 3.0L turbo---1965 Crown V8
1967 monza 110/4---1968 monza 110/4
1971 amante gt 110/4
CORSA/RMC/PPCC/V8 Registry

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Re: throttle linkage adjustment - 65 turbo
Posted by: jjohnsonjo ()
Date: July 26, 2022 12:40PM

steve c goodman Wrote:
-------------------------------------------------------
> I don't have any potatoes hanging around so I roll up a couple of red shop rags and while engine is warm and at idle I stuff the rags into the exhaust outlet and hold in place with a hammer handle. As JO states, if engine is still running after a minute you are leaking exhaust.


I live in the middle of a potato farm, never any shortage of food or potato canon ammo. LOL

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


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Re: throttle linkage adjustment - 65 turbo
Posted by: jeffmort ()
Date: July 30, 2022 11:55AM

So I have corrected my throttle linkage. I replaced an aftermarket swivel joint linkage piece with the a stock link (the link from the crossover shaft to the carb). I also found that the cross shaft was installed backwards so I flipped it around and installed it correctly. After doing this I was able to set the throttle linkage properly getting the linkage to to the carb's throttle stop boss and the linkage at the transmission to its throttle stop.
With these corrections I was able to get to 3-4 lbs boost (before these corrections I was getting no boost).
So now I am going back to checking the exhaust again for any possible leaks that my last exhaust guy may have missed.
At least one step in the right direction!

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