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Re: Dead Cylinder - Coil Overheating?
Posted by: Carburetor ()
Date: August 26, 2019 06:08AM

Well this is somewhat embarrassing…

After disappearing for a week bouncing around Michigan’s upper peninsula, I finally had a chance to replace the coil and take it for a test drive. Got about a mile down the road and at the first red light, the misfire was back.

Work and family stuff started piling up, so I didn’t have a chance to get back into it this until this weekend. The next place I looked was the spark plug and wire. I replaced the wire with an old one I had laying around. Same thing as the coil – started up fine, and at the first red light the misfire was back. Same thing – cylinder #1 was dead. Replaced the plug with a new one (NGK B6HS) and started it up. Same thing as before – smooth idle. Gave it some gas to kick the idle down, and now the misfire is back. That hasn’t happened before -what gives? I pulled the #1 wire off of the cap, and no change, so it’s still #1 dropping out. However, putting the wire back on the cap, I slipped and hit the RH secondary link, and the idle immediately smoothed out. Huh??? I goosed the accelerator a couple of times, and she settled into a smooth idle. I then gradually gave her some gas, slowly eased off the accelerator, and the misfire is back. Back into the engine compartment, and I push on the RH secondary link to close the throttle. Misfire goes away. If I gently crack open the RH secondary and let it close on its own the misfire comes back, but if I snap it open and let it snap back it doesn’t. So, it appears my ignition problem is actually a problem with the way I have the secondary linkage set up. I can repeat this at will – I even show my wife (she wasn’t impressed). I can do it with the LH secondary by just cracking it and holding it there, but it closes on its own. Time to redo the secondary linkage – ran out of time last night.

I have the stock ’66 linkage but the secondary carbs have had the lockout mechanism removed by a previous owner, so the procedure in the assembly manual and service manual doesn’t work. I believe I set the secondaries up so the springs just barely contact the link arm at idle (can’t remember the details at the moment) but it appears the RH is set so a gentle application of the throttle allows it to hang open at idle which is leaning out #1 to the point where it won’t fire.

Jim C.
Chesterfield, MI

1966 Monza convertible (140 / PG)
2017 Chevrolet Trax (daily driver)
2017 Chevrolet Volt (wife's ride)


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Re: Dead Cylinder - Coil Overheating?
Posted by: MattNall ()
Date: August 26, 2019 07:28AM

Accel pump spring is the wrong one... secondaries are stiffer... worth a check.

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Dead Cylinder - Coil Overheating?
Posted by: JimBrandberg ()
Date: August 26, 2019 07:36AM

It takes some time to get linkages and such operating freely sometimes. Sometimes a little bending or smoothing or lubricating is in order. It's good that you have a trail to follow.

Try doing what you can without adding more or bigger springs. If too much force is required the chassis linkage can fail to push open the secondaries.
Above suggestion for checking the spring inside under the accelerator pump is valid though.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Dead Cylinder - Coil Overheating?
Posted by: Carburetor ()
Date: August 26, 2019 08:09AM

I tore apart the carbs for a spring cleaning a few months ago and confirmed that the accelerator pump return springs were correct. I remember because one of the secondaries had the wrong return spring - luckily I have a oouple of spare secondaries that I stole a spring from.

Jim C.
Chesterfield, MI

1966 Monza convertible (140 / PG)
2017 Chevrolet Trax (daily driver)
2017 Chevrolet Volt (wife's ride)





Edited 1 time(s). Last edit at 08/26/2019 08:12AM by Carburetor.

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Re: Dead Cylinder - Coil Overheating?
Posted by: Carburetor ()
Date: September 04, 2019 09:10AM

Way overdue for an update, so here goes.

Readjusted the RH secondary rod to shorten it, and the issue is fixed. Took her for a spin (last week) to confirm.

Jim C.
Chesterfield, MI

1966 Monza convertible (140 / PG)
2017 Chevrolet Trax (daily driver)
2017 Chevrolet Volt (wife's ride)


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Re: Dead Cylinder - Coil Overheating?
Posted by: MattNall ()
Date: September 04, 2019 05:45PM

Have you checked to be sure all 4 carbs are at WOT at the same instant?

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Dead Cylinder - Coil Overheating?
Posted by: Carburetor ()
Date: September 05, 2019 04:01AM

That is my next step - I think I have the secondaries opening too early as I have a bog if I floor it from a stop but runs fine if I ease into the throttle (but what fun is that?).

Jim C.
Chesterfield, MI

1966 Monza convertible (140 / PG)
2017 Chevrolet Trax (daily driver)
2017 Chevrolet Volt (wife's ride)


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Re: Dead Cylinder - Coil Overheating?
Posted by: rnch ()
Date: September 06, 2019 09:26AM

MattNall Wrote:
-------------------------------------------------------
> Jim.... first thing...
>
> Move the coil to the verticle bracket behind the license plate.. wires reach easily.
>
> And plug the hole under the coil, if there is one.


Yup! I have done this simple mod on almost every Corvair I've owned.

Coil runs cooler away from the engine heat and less vibration in this new location.

thumbs up

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Re: Dead Cylinder - Coil Overheating?
Posted by: JimBrandberg ()
Date: September 11, 2019 07:32AM

I worked on a 63 102HP PG with 14,000 miles on it yesterday on my way to the Corvair club meeting. He reported that it ran good for 1/2 hour or so and then wouldn't want to idle in Drive. He said last time he was out with it he had trouble getting it to restart in order to get back home. It has stock points and condenser.

When I arrived it was already warmed up. I verified that it ran poorly in general and had sort of a misfire blip when idling in Neutral. I verified that it had a nice spark with the coil wire to ground and the engine turning over with the starter. I installed my test carburetors and it was about the same. I opened up the 102 carburetors and they were fine, good fuel level and accelerator pump squirt. The coil felt hot but I'm not sure I'd say too hot, with the damper doors closed it had hot air blowing on it through the slots on top of the ducts. The dwell was good and steady when revved. The voltage to the + side of the coil went from 12 to 6 as the points opened and closed while turning the engine over with a wrench. I remembered from working on it a few years ago that it liked excessive ignition timing to run well which I didn't like but it wasn't up to me how much time to spend on it at that time.

I installed a new coil and all is well. The idling misfire blip is gone and it's happy at 14 degrees initial timing. It idles good in Drive. It's a mystery to me why excessive timing would help mask a weak coil. It's a mystery to me why it was misbehaving yet still showed a nice spark from the coil wire to ground.

I thought about adding to this recent thread even though that doesn't seem to be the trouble here anymore. I'm thinking of posterity when someone does a future search.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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