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Advice needed
Posted by: corvairtherapy ()
Date: February 08, 2022 02:34PM

I could use some help with this problem I am having with a '63 Monza coupe, 102 hp engine with powerglide. It has freshly rebuilt carbs that have been balanced, the dwell is set at 34, timing at 13 degrees and it had a tune up (points, condenser, rotor,cap,plugs and wires by the previous owner. The car will start and idle smoothly for any length of time but when put into gear it will get slower and slower until it dies. It will start right back up again and sit and idle smoothly until put in gear when it happens all over again. There are no vacuum leaks that I could find. I'm running out of ideas so I am reaching out for suggestions, or better yet, a solution! GGG Any help out there?
Dave.. .

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Re: Advice needed
Posted by: Phil Dally ()
Date: February 08, 2022 02:41PM

What is the plug gap set at?

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Re: Advice needed
Posted by: davemotohead ()
Date: February 08, 2022 02:46PM

Sounds like a Vacuum leak to me, Plug off the Vacuum tube going to the Trans modulator at the carb balance tube, just cap that port off and see if it still does it?







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Advice needed
Posted by: corvairtherapy ()
Date: February 08, 2022 02:53PM

Phil, .035

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Re: Advice needed
Posted by: corvairtherapy ()
Date: February 08, 2022 02:54PM

Will do tomorrow morning, screw it for tonight.
Thanks Dave, Dave... .

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Re: Advice needed
Posted by: davemotohead ()
Date: February 08, 2022 03:01PM

A engine with no load on it and a vac leak will idle fine, once in gear and the engine has a load on it a vac leak will make it die just like that, also Plug off the Vac advance on the distribuitor. just for testing.







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Advice needed
Posted by: RexJohnson ()
Date: February 08, 2022 03:07PM

What is the idle speed in gear?

RJ tools
Salem,Oregon

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Re: Advice needed
Posted by: corvairtherapy ()
Date: February 08, 2022 03:29PM

will do

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Re: Advice needed
Posted by: corvairtherapy ()
Date: February 08, 2022 03:30PM

Rex, 600 before it dies
Dave.. .

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Re: Advice needed
Posted by: Timothy Shortle ()
Date: February 08, 2022 03:33PM

Dumb question: why do you let it idle IN GEAR. Or are you saying when at a stop light? Some of my PG Corvairs I usually just put it into neutral if I am just going to sit somewhere with the engine running.

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Re: Advice needed
Posted by: RobertC ()
Date: February 09, 2022 01:17AM

corvairtherapy Wrote:
-------------------------------------------------------
> Rex, 600 before it dies
> Dave.. .

Think you need to raise the idle speed a little - 750? - for a PG.

But, as davemotohead stated - vacuum leaks...

Replace hoses at vacuum modulator and balance tube.

Replace balance tube hoses at carb bases. I use 3/8" compression unions.

Do you have the 1/4" phenolic "spacers" under the carbs?

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Re: Advice needed
Posted by: vairmech ()
Date: February 09, 2022 05:31AM

Look at the vac advance as it is idling in neutral. Is it advanced? If there is a question about that unplug the line and see if it moves.

If it moves then what is happening is when the engine is put in gear it loses a little vacuum, just enough to retard the timing a little and the engine slows down. As the engine slows down there is less vacuum and the advance retards a little more and the engine slows more. This will continue until the engine stalls, been there done that!

At this point make sure the timing is set with the vac hose off and where the timing is. You may have to go through and set everything up correctly.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Advice needed
Posted by: JimBrandberg ()
Date: February 09, 2022 07:28AM

I think of .035 plug gap with a hotter ignition but .030 usually. I wouldn't mind if someone thinks I'm off.

Ken's idea with the vacuum advance is good and the other vacuum ideas too. I like the thin gaskets on both sides of the insulator block but that's debateable.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Advice needed
Posted by: 66vairman ()
Date: February 09, 2022 08:53AM

vairmech Wrote:
-------------------------------------------------------
> Look at the vac advance as it is idling in neutral. Is it advanced? If there is a question about that unplug the line and see if it moves.
>
> If it moves then what is happening is when the engine is put in gear it loses a little vacuum, just enough to retard the timing a little and the engine slows down. As the engine slows down there is less vacuum and the advance retards a little more and the engine slows more. This will continue until the engine stalls, been there done that!
>
> At this point make sure the timing is set with the vac hose off and where the timing is. You may have to go through and set everything up correctly.

Ken brings up an important issue. Normally at idle the carburetor(s) vacuum timing port is covered by the throttle plat posistion so there should be no vacuum advance --- HOWEVER the distributor vacuum advance hose only connects to one carburetor. Once I had a car that would allow vacuum to the distributor vacuum advance canister at idle. It had similar symptoms you describe. I disconnected (and plugged) the vacuum advance hose and the car idled fine (after I set set the timing). The problem was the carburetors were out of balance and the one with the distributor vacuum hose had the idle set too high to keep the engine running so the distributor vacuum port was uncovered and supplying some vacuum to the distributor. As Ken said as the idle dropped the vacuum dropped and the timing retarded causing the idle to drop more until it stalled.

Not saying this is your issue. Check to make sure there is not vacuum to the distributor at idle in neutral. If there is - balance the carburetors first.

The other issue is static timing. Especially on the later SMOG equipped PG cars you must set the static timing at 600RPM or less as the centrifugal timing starts to advance at about 650 750 RPM.

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Re: Advice needed
Posted by: corvairtherapy ()
Date: February 09, 2022 10:40AM

This mornings update:
All hoses were replaced, two on the modulator line, two on the balance tube and the vacuum advance hose. Made no difference, it will still die out over about 15-20 seconds. I can get it to idle in gear at 600-650 rpm if the engine is up to temp but not consistently. It will sometimes still slowly die. I have also removed the gas cap while it is running to see if the vent is plugged, no joy. As I said in the first post, the carbs are rebuilt and balanced, have insulators and gaskets, the timing set at 600 rpm with hose disconnected and plugged. I did notice a slight tapping noise but could not tell where it was coming from so I got out my stethoscope and started searching. I couldn't locate the source of the noise until I touched the vacuum advance arm. It sounded like a machine gun. WTF? I'm at a loss, Pull the distributor?

Timothy, I let it idle in gear because the factory made it that way and my customer wants it that way. Shifting to neutral at red lights is not a viable solution.

Robertc, The factory spec is 500 Rpm in drive, wish I could do that. At 750 there is too much clunk going into gear.

Vairmech, All good advice but as stated before all is correct.

Jimbrandenberg, The factory spec is .035 for this particular engine. It does have Champion plugs in it which I am sorely tempted to replace with AC44FF's

I appreciate all the responses but the problem is not yet solved so Keep'em coming please.
Dave.. .

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Re: Advice needed
Posted by: RobertC ()
Date: February 09, 2022 11:04AM

corvairtherapy Wrote:
-------------------------------------------------------
> This mornings update:
> so I got out my stethoscope and started searching. I couldn't locate the source of the noise until I touched the vacuum advance arm. It sounded like a machine gun. WTF? I'm at a loss, Pull the distributor?
>

That is weird.

Can you hear the same noise with the stethoscope on the distributor housing?

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Re: Advice needed
Posted by: davemotohead ()
Date: February 09, 2022 11:43AM

Did you do what I said and cap off the vac advance and the modulator eliminating them from the system?, just replacing the hoses does nothing if the vac advance or the modulator them selves have a internal leak? I have seen cracks and holes in the modulator line itself before, Also have you taken carb cleaner and sprayed it around the base of the cabs to see if the idle changes? old school way to find vac leaks.







1960 4dr sedan caveman car
1961 Rampside (Chetside)
1962 Rampside (Barnside)
1962 Short Rampside (Shortside)
1962 Monza 700 Wagon
1963 Monza 900 coup (General Nader)

-----------------------------------
Rust Free Lancaster Ca

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Re: Advice needed
Posted by: 66vairman ()
Date: February 09, 2022 04:40PM

RobertC Wrote:
-------------------------------------------------------
> corvairtherapy Wrote:
> -------------------------------------------------------
> > This mornings update:
> > so I got out my stethoscope and started searching. I couldn't locate the source of the noise until I touched the vacuum advance arm. It sounded like a machine gun. WTF? I'm at a loss, Pull the distributor?
> >
>
> That is weird.
>
> Can you hear the same noise with the stethoscope on the distributor housing?

You can check for fluctuating vacuum, but if the vacuum advance canister arm makes that noise with the vacuum hose disconnected then it's something hitting the points pivot plate or rotor is hitting something. I'm assuming the points plate pivot is in good shape. You may have to remove the base/pivot plate assembly and look at the centrifugal weights and springs.



Edited 1 time(s). Last edit at 02/09/2022 04:42PM by 66vairman.

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Re: Advice needed
Posted by: RobertC ()
Date: February 10, 2022 01:55AM

Do not think the distributor has to be removed. But, as 66vairman states: remove the cap and the point plate to look at the weights / springs.

Decades ago, I had a distributor spring come off. The loose weight wore a groove in the side of the distributor housing - though I do not recall any performance issues (110/PG).

Personally, I would replace the Champion plugs (though not your problem) - especially if they are extended tip.

Another item to check is the hole in the arm of the vacuum advance. After decades, the hole can be an oval.

Again, I think you need to perform the tests posted by davemotohead / others.

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Re: Advice needed
Posted by: roger65180 ()
Date: February 10, 2022 05:45AM

I have a story exactly like this in fact it's too long to post all that was found , customer car 63 102 PG . several shops ahead of me . wrong didst,turbo advance weights , added balast such as 63 turbo, carb throttle shafts worn including holes in cross shaft, and carb arms , voltage drop a little to much when idleing in gear. final aha gap plugs to 0.025 AND the Ign swicht was the voltage loss , the .025 plug gap is in the service manual, the ign switch is un obtainium, because of being PG no other switch fits except generic owner want original I got 1 from the source ( David Harrington )

Roger R
Madison Wi
62 ct pg turbo
65intercooled 180 4sp,autocrosser
62 Rampy

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