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My first timing adjustment and advice sought
Posted by: Saxon ()
Date: July 15, 2020 06:58AM

Hi,

I have pinging on a 106K 140 hp 4-speed when I go up mild grades or pressing the accel. pedal to the floor in 2nd gear and above. I am running 91 Octane.

I have tried Sea Spray aerosol according the manuf. directions. No effect to very little effect in resolving. Did not see any smoke of any color upon start up, possibly because I was at the drivers seat.

I have tried Octane boost to no effect.

I have tried a lead additive to no effect.

I have tried kind words words to no effect.

Yesterday, I bought my first timing light and decided to retard the timing down to 16 degrees from the original 18 degrees.(final adjustment fluctuated between 16-17 degrees by itself).

Before the adjustment, I had the vacuum hose removed at the vacuum diaphragm end and plugged hose with golf tee. (Hmm, should this have been removed at the carb and plugged?!)

I did not see a timing change between vacuum and non-vacuum at about 950-1000 rpm, my warmed idle.

After the timing adjustment and connecting the vacuum, I revved the engine to 3000 rpm repeatedly, but did see an movement on the external part of the diaphragm. Should I see the metal hinge/cam connection move?

Now that I recall, I don't think I checked to see if the timing advanced with the revs. I will need to check that today.

It idled a tad rougher at 16 degrees but I think it took just an edge off the pinging on mild grades. Still get pinging when accelerator pushed to floor, but pinging is removed when I am at steady 2nd gear throttle at upper rpm on a 10 degree hill, less than 1000 feet.

Thanks!

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Re: My first timing adjustment and advice sought
Posted by: JimBrandberg ()
Date: July 15, 2020 07:37AM

You should see the vacuum advance moving when operating the throttle up and down.

When I do Sea Foam for possible carbon treatment it's the liquid poured slowly into the running carburetors and surrounded by choking smoke. It's quite a spectacle.

The timing changing a few degrees is interesting. I wonder if a Dwell Meter would change too. What I'm wondering is if the distributor shaft bushing is worn causing the points to do odd things on one side compared to the other.

No vacuum advance at idle is usually a good thing meaning that your carburetor is turned down far enough to be in the idle circuit.

With the vacuum advance disconnected you should be able to see the mechanical advance with the light as you increase the engine speed.

Do you know what distributor you have? The number is on the outside clockwise from the vacuum advance. A number like 1110xxx where the last 3 numbers mean something. I would expect 330 on a 140 HP.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: My first timing adjustment and advice sought
Posted by: corventure Dave ()
Date: July 15, 2020 08:08AM

I would also look for vacuum leaks. The choke break diaphragms can be working but also leaking. Check all vacuum hoses and their connections. also Carburetor base gaskets.
A vacuum leak creates a lean issue that can contribute to detonation-ping.

The crank pulley timing mark can move. There is mark on the inner part of the pulley that aligns with the outer ring of the harmonic crank pulley. I have seen this mark off by nearly 1/4 rotation from where it should be. That engine, the owner said he could not set the timing so the engine would run at all. I was surprised the balancer had slipped so far without any sign of a wobble!

Corventure Dave

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Re: My first timing adjustment and advice sought
Posted by: joelsplace ()
Date: July 15, 2020 10:42AM

Don't forget to check the hoses at the base of the carburetors going forward to the balance tube. Those get cooked from the heat and leak.
I've seen bad balancers where the timing mark went round and round with the engine running but they didn't wobble. This doesn't sound like a bad balancer but it does need to be checked.
Heat? Does it ping after driving it a while but not when the engine is cool? You may need to deflash the heads.

Joel
Northlake, TX
5 Ultravans, 141 Corvairs and counting...

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Re: My first timing adjustment and advice sought
Posted by: Saxon ()
Date: July 16, 2020 07:11AM

I like those suggestions and questions! They bring up further questions & ideas for myself.

I did NOT (left out that important adverb) see any movement in that external metal diaphragm hinge/cam when revving to 3000 rpm.

I will still check to see if the timing advances with 3000 rpm revs. My understanding is that in weights inside the cam will extend to advance the cam, too.

The visible distributor numbers I can see are x0330.

I forgot to mention that it has a Petronix ignitor and coil (car is still 2 months new to me). I read that is an electronics conversions so I take it that points and dwell are a bygone for this ignition system.

Also forgot to mention there is no AIR injector system.

Will I be able to physically move with my hands any slippage between timing ring and harmonic balancer or will it just be obvious from a static visual inspection?

My pinging takes no nap. It is present after warm up or anytime during my usual 2 hr, alternating evening sporting gentlemen's spin. Yes, from time to time the car diesels/pings after I shut it down from a 70 degree evening ride which involves 20 minutes on the Freeway + suburbs streets, 40 minutes in the 2nd gear canyon (revs medium to high) and the same freeway suburbs back.

By deflashing I believe that means scraping any metal between the fins of the cylinder heads.

Oh, is there any relationship between what I may be experiencing and the black exhaust streaks on the garage floor upon start up. They are low in "pixel" density and when it I wiped it with a white napkin (not immediately afterward), it appears to be soot.

I think I'm gonna try using the vacuum gauge that came with my Pittsburg brake bleeder.

Question, why is timing set at idle when most of the engine use is in higher revs?

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Re: My first timing adjustment and advice sought
Posted by: JimBrandberg ()
Date: July 16, 2020 07:32AM

I'll sort of go in order that things appear in your last message.

Some thought should be given to whether it is a black Pertronix 1 or a red Pertronix 2, they use different coils ans are wired differently. There were threads "Pertronix 1 Wiring" and "Pertronix 2 Wiring". Be sure to change the search function to "All Dates" or it only goes back 30 days. It's probably not your immediate issue but something you should do.

The harmonic balancer usually has a little index line on both sides of the rubber inline with the timing notch on the pulley. It won't move by hand until it gets really bad.

I use a Sawzall blade in a vicegrip for deflashing. It's the fins in the middle that need attention. You have to remove some stuff to get there and a little tedious once you do.

Simply stated, black soot is more about fuel mixture than ignition timing. Sometimes people richen up the main jets in an attempt to quell pinging.

I'm not comfortable with high RPMs peering at the light with the fanbelt in my face. You can make some marks and do it or use an advance adjustable timing light but I'm not going to do it, but then I have a distributor test machine. Your point about the total advance at high RPMs being the most crucial is quite valid.

These are just off the cuff comments and some may not agree or have more to say. I enjoy reading especially if I'm missing something.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: My first timing adjustment and advice sought
Posted by: joelsplace ()
Date: July 16, 2020 09:21AM

I'm not sure what you are calling a cam. The only thing that you can see move while the engine is running is the arm coming out of the vacuum advance. It shouldn't move on acceleration but will pull in on deceleration and then let out again when the engine comes to idle. These things happen fast. If you hold the engine at a steady higher RPM it should pull in and stay there.

Joel
Northlake, TX
5 Ultravans, 141 Corvairs and counting...

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Re: My first timing adjustment and advice sought
Posted by: corsa1 ()
Date: July 17, 2020 05:00AM

use 93 octane

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Re: My first timing adjustment and advice sought
Posted by: Frank DuVal ()
Date: July 17, 2020 07:35AM

Quote
Jim
When I do Sea Foam for possible carbon treatment it's the liquid poured slowly into the running carburetors and surrounded by choking smoke. It's quite a spectacle.

I just use water. Pour it form a "pop" "soda" 'beer" bottle.grinning smiley

Frank DuVal

Fredericksburg, VA

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Re: My first timing adjustment and advice sought
Posted by: roger65180 ()
Date: July 17, 2020 04:39PM

your rpm is too high to set timing you must be below 750 rpm. the timing movement is caused by the rpm functioning the advance in the dist . I suspect possible over heat causing the ping . have you deflashed the heads and cleaned the oil cooler,all of this matters

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

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Re: My first timing adjustment and advice sought
Posted by: American Mel ()
Date: July 17, 2020 07:39PM

Frank DuVal Wrote:
-------------------------------------------------------
>
Quote
Jim
> When I do Sea Foam for possible carbon treatment it's the liquid poured slowly into the running carburetors and surrounded by choking smoke. It's quite a spectacle.
>
>
> I just use water. Pour it form a "pop" "soda" 'beer" bottle.grinning smiley


Agreed.
BUT, occasional use of Techron in your tank helps to reduce the need for even using the water treament.

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WA. state, 1 mile south of the Canadian border, I am not at the end of the world, but you can see it from here.

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