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Re: Many of you have experienced this...
Posted by: Richard ()
Date: September 16, 2022 06:13PM

In May you had some kind of carb problem with a Power Valve block-off and jetting change. Did you ever get that sorted, before you pulled the transaxle?

Four years ago you had questions about your PCV setup.
You had Manifold Vacuum for the dist. at C.
Dash Vacuum Gauge at B. Ported vacuum.

You don't have choke? AS I assume you have the choke tied open, have you checked to see if it has become loose?

When you remove the choke on a Holley, there is a vacuum port that needs to be blocked closed. I do see a screw head on the side of the carb. Is that the vacuum port as T don't recall the location for sure



Edited 1 time(s). Last edit at 09/16/2022 06:15PM by Richard.

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Re: Many of you have experienced this...
Posted by: cnicol ()
Date: September 16, 2022 07:05PM

While I have "experienced" this issue, I've had to open the thread half a dozen times to "remember" what it's about! Glad to see you're getting some good direction though.smileys with beer

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Many of you have experienced this...
Posted by: PequotMonza64 ()
Date: September 16, 2022 10:00PM

Go with the simplest explanation first. Does sound like vapor lock. When you stop with a hot engine, the carbs (carb?) just soak up the heat.

And your in Arizona...

Glen in Ohio
1964 Monza Sedan Powerglide 110 hp
Low mileage survivor, stock as delivered
Records back to 1967 in Pequot Lakes, Minnesota
Original dealer Mike Turk's in East Liverpool, Ohio
Located in Cleveland, Ohio area


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Re: Many of you have experienced this...
Posted by: Unsafe140 ()
Date: September 17, 2022 04:19PM

Richard good detective work, yes I went ahead and decreased jets by 7 and installed an 8.5 power valve and I like to way it runs and when I've been driving. Was way to rich especially at idle.

Also, took care of the other issues before the diff rebuild.

So I havent checked the coil. I dont believe its vapor lock but it sure
acts like vapor lock. With a center mount its not taking heat from the heads like a stock setup. hmmmm....?
After the car sat for a couple days and turned the key it started nearly instantly.

Never had vapor lock in the past maybe I will need to add that electric fuel
pump going forward.

Joel
Cave Creek, AZ
1965 Corsa 140 tele

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Re: Many of you have experienced this...
Posted by: link9711 ()
Date: September 18, 2022 06:43AM

Hi again what I would do is frist see if it will start if it does run it untill it starts doing the dieing thing then when it wont start take the air filter off and move the throttle and see if gas squirts out from the pumps in the carb if so unplug the coil wire and crank it and see if you have spark has to be one or the other failing.hope this helps wish I lived close would like to look at that beauty.



link9711
63 monza spyder
san antonio tx

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Re: Many of you have experienced this...
Posted by: link9711 ()
Date: September 18, 2022 06:51AM

How old is that gas psi reducing valve that could be turning off at a idle starving the carb if it does not squirt in the carb I would look at that item maybe bypass it temp for testing.

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Re: Many of you have experienced this...
Posted by: cnicol ()
Date: September 18, 2022 08:38AM

Your comment that the engine revs to 3000 when it does restart makes me think you're (possibly) experiencing the age-old "it loads up" at idle and dies issue that occurs with some center 4-bbl conversions. This occurs because of cold manifold tubes and slow (idle) airflow. The issue is compounded by (possible) connection of the vacuum advance to "manifold" rather than "ported" vacuum.

The usual cures include carburetor tuning, manifold heat, and confirmation that the VA is connected to ported vacuum on the carburetor.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Many of you have experienced this...
Posted by: Unsafe140 ()
Date: September 18, 2022 07:55PM

Good idea to check psi valve is pretty old now checking that should be done either way. Maybe chuck it in the trash.

Craig thanks for this piece of info. This may be the issue.
Since the carb was just rebuilt maybe i need a bit of adjustment to keep this issue at bay.

Joel
Cave Creek, AZ
1965 Corsa 140 tele

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Re: Many of you have experienced this...
Posted by: Brizo ()
Date: September 18, 2022 11:31PM

Unsafe 140, Twenty posts were made on this thread in an effort to help you before we found out you have a center mount Holley and not the stock carbs.
Now we find out you have a fuel pressure regulator also. If you expect accurate advise, we need accurate and complete information to work with.

Dan Brizendine, Circle City Corvairs
'64 8 door Greenbrier, +.060, stroked 1/4", 188 ci, 140 PG. "In beautiful Wanamaker Indiana...with one stop light and 5 pizza shops"



Edited 1 time(s). Last edit at 09/18/2022 11:38PM by Brizo.

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Re: Many of you have experienced this...
Posted by: chuckvh ()
Date: September 19, 2022 09:20AM

The picture that was posted above is a holley two barrel, and not the 390 4-barrel that I’m familiar with. What is the list number of the Holley carburetor that is installed on your engine? You should be able to find the list numbers stamped in the carburetor choke air horn.

Chuck vonHofen
Brentwood, California

66 Corsa Turbo Convertible
64 Spyder Coupe
Too many boats
Amazingly Patient Wife

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Re: Many of you have experienced this...
Posted by: Unsafe140 ()
Date: September 20, 2022 08:29AM

I havent checked the coil yet.

Craig, thank you I think you are on to something.
I have never had the "load up" issue in the past,
but now that the carb is redone with a different
Jet and power valve set up I may need some more carb tuning
to see if that helps. This issue never crossed my mind.

Joel
Cave Creek, AZ
1965 Corsa 140 tele

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Re: Many of you have experienced this...
Posted by: jamesolefjensen ()
Date: September 20, 2022 02:48PM

My 390 (8007) Holley used to have the "load up" problem. The symptoms were very similar to what is described in this post.

I could tell when it was about to die and if I could, I'd rev it up, it would "clear its throat" and idle OK again. If it died, I had a hard time starting it (had to hold the throttle wide open, blah blah blah).

As stated earlier, the center mount manifold runs cold and fuel readily condenses inside. At idle, there is not enough airflow to push the condensed fuel to the cylinders and eventually enough of it puddles under the carb to cause an over rich condition that kills the motor. At least that's my half brained, unproven theory.

Here is my idle tuning recipe:

- Idle is set to 800-1000 RPM
- Seth's HEI ignition with full manifold vacuum to the vacuum advance
- Idle mixture screws ~1/2 turn out from "lean roll"

The air cleaner is a GM factory "Thermac" housing with a warm air duct routed from a modified summer/winter air door to the snorkel. This didn't cure the loading up problem but its worth mentioning. Also worth mentioning is that there are no insulator pads under the legs of the manifold. This was all done in a effort to put heat into the manifold.

I am not sure what I did to cure it but it doesn't "load up" anymore. My best guess is the higher than normal idle had the biggest effect.

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Re: Many of you have experienced this...
Posted by: cnicol ()
Date: September 20, 2022 03:37PM

I like everything proposed by "James of Jensen" except for the "Full manifold vacuum" to VA part. While lean cylinders will thrive on the high advance, getting there through "full manifold vacuum" is a recipe for a stall.

Why? Because as the engine begins to falter, manifold vacuum drops and you lose the much needed advance. As the advance falls, the engine slows and falters even more. It's a death spiral until vacuum is lost, advance is lost, and the engine quits.

It's far better to "bake" that same level of advance into the initial timing and reduce total mechanical advance so you end up with the same final timing. This is really easy to do with an electronically controlled spark advance such as Megajolt or the CB "BrownBox". (It's really called the "BlackBox" but that's my trademark.)

FWIW, modern factory-build EFI engines often use an idle timing of 30 degrees so the idle can be clean and lean rather than the 12:1 AFR that we see in older carbureted engines.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

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Re: Many of you have experienced this...
Posted by: Unsafe140 ()
Date: September 20, 2022 06:37PM

Thanks everyone. I did mention the center mount back on sept 9 but I should have made clear up front. My posting is on and off so I should remind if looking for symptom advice.

I do believe it is the load up scenario. With work family etc haven't has a chance to make adjustments. Did start it though and it started right up and idled fine. Didn't drive it. Especially because it is not the 390 not sure were my brain was at that time. It makes sense that the flow would be slow at idle as its a 500 2 barrel. Jetted down mind you but still.

I do generally keep my idle 900-1000. Below 900 asking for stall. Im fine with it.

Next time I drive and try to back it in the garage we'll see if it stalls again.

Joel
Cave Creek, AZ
1965 Corsa 140 tele

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