Dead cylinder help

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Jonathan Halpern
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Tag: 1964 356C built 7/16/63 1987 911 Carrera
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Dead cylinder help

#1 Post by Jonathan Halpern »

Hey guys and gals,

A bit stumped. 356C with Zenith 32NDIX’s, rebuilt a few years ago. Cylinder 3 is doing little to nothing. I have spark, I checked this by jumping the spark plug end of the wire to the chassis. I’ve cleaned the idle jets several times as well as the main jets. She starts right up, idles low and pulling one plug at a time shows 1, 2 and 4 causing it to nearly stall. Pulling plug to 3 does almost nothing, maybe a millisecond blip to idle. I pulled the #3 plug and it was a bit wet from fuel. Idle speed is way down. Getting RPM’s up to 3k or so causes backfiring through exhaust Which leads me to believe too rich and a wet plug tells me the same yet ignition appears fine. Car was fine before being placed in storage for a few months. I sprayed some carb cleaner into the jet orifices in the carb body as well as cleaning them thoroughly top to bottom. Carb cleaner sprayed at the manifold and around the carb base didn’t raise idle. Cylinder 1 firing perfectly. Could something cause a very rich condition in just cylinder 3? Mixture screw is around 1.5 turns out.
Engine was rebuilt a few years ago, top end plus new pistons and cylinders. Zenith rebuild. Valves adjusted not long before heading to storage. Timing is set correctly.

Any tips would be appreciated.

Thanks!

Jonathan

John Ward
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Re: Dead cylinder help

#2 Post by John Ward »

I would take a compression test.
Even though you adjusted the valves, I would still check them.
Also, check the float, and needle and seat.
Hope that helps
 

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Don Gale
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Re: Dead cylinder help

#3 Post by Don Gale »

Also, swap cyl. 3 plug with one of the others and see if that plug is dead.
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Jonathan Halpern
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Re: Dead cylinder help

#4 Post by Jonathan Halpern »

Thanks guys, I will check the valves next once I free up my lift and do a compression test as well. Why does it have to be #3... couldn’t be an easy cylinder to get to!

Jonathan

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Martin Benade
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Re: Dead cylinder help

#5 Post by Martin Benade »

My first suspect would be the plug wire or connector.
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Jonathan Halpern
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Re: Dead cylinder help

#6 Post by Jonathan Halpern »

I will swap the plug wires to confirm. I confirmed sparking at both ends. I’ll do a measurement and make sure its not gone high impedance on me. Spark plug looked okay, evidence of being slightly rich but wet. Slightly rich is not unexpected as I drive at higher altitudes often without retuning.

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Harlan Halsey
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Re: Dead cylinder help

#7 Post by Harlan Halsey »

Driving at high altitude from Long Island is quite a trick!
Sounds like #3 is not firing. An old trick is to gap the plug wire about a quarter of an inch. This will often fire a lightly fouled plug. If the spark won't jump the gap, then suspect the plug, wire, cap, and rotor in that order. (I once had a misfiring problem which I only solved by observing the engine running in the dark. Spark was jumping from the coil wire to all four plug wires just above the cap. Pretty neat looking. New wires fixed it.

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Re: Dead cylinder help

#8 Post by David Nicholls »

Dear Jonathan

Another suggestion to add,
Run the engine at a bit more than 2000-2500 rpm for a minute then turn the engine off.
Have a feel of the No3 exhaust pipe under the car and before the muffler.
If it's hot then No 3 is working.

Regards David

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Jonathan Halpern
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Re: Dead cylinder help

#9 Post by Jonathan Halpern »

Ah, I should update my profile. Moved from Long Island to Southern California last year. Car is stored in my garage at sea level, I live at 4300’.
Okay, more good ideas to try and check. It is behaving so much like an ignition issue. I will confirm the exhaust from #3 is cold as well.
Its car failures week for me, three cars with three different issues.

Thanks!

Jonathan

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Martin Benade
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Re: Dead cylinder help

#10 Post by Martin Benade »

How many stairs from your garage up to your house?
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Jonathan Halpern
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Re: Dead cylinder help

#11 Post by Jonathan Halpern »

6,880, we followed code. Really gets your heart pumping. Bringing groceries in can be a pain.

We have a garage condo, didn’t even know such a thing existed until recently. Its a great concept.

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Re: Dead cylinder help

#12 Post by John Ward »

You live at 4300 ft.?
Where do you live ?
 

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Jonathan Halpern
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Re: Dead cylinder help

#13 Post by Jonathan Halpern »

San Jacinto/Santa Rosa Mountains in the San Bernardino National Forest.

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Craig Richter
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Re: Dead cylinder help

#14 Post by Craig Richter »

John lives at mile-high Lake Arrowhead, which also happens be where I grew up. Not that this has the slightest to do with your problem, but we do know altitude. 6,880 steps? What?? Mandy and I live at 7,000' now, and I'm huffin' and puffin' just to bring the groceries up 6 steps. I salute you, Superman.

Do you have stock-type spark plug connectors? The brass recepticle that pushes over the threaded spark plug end actually screws in place up inside the bakelite tube, and can loosen over time, breaking the continuity. The long-shank flat-blade screwdriver in your tool kit is perfect to cinch it down again. These guys are so fast and smart on this forum, they already told you about all else that could be culprit, so I thought I'd throw in something a bit odd people sometimes forget to check...
 

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Jonathan Halpern
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Re: Dead cylinder help

#15 Post by Jonathan Halpern »

Thanks for the additional tips, Craig. I don’t have the original style wires, these are a set that came from Stoddard a few years back. I just got in some new spark plugs, I need to give them a try. I’m wondering if a nearly new plug bit the dust somehow. I noticed they were made in Russia, thats a new one to me. If it turns out to be a failed plug, I’ll be very happy. While I have that pesky #3 out, I’ll see if it sparks to the chassis.

Lake Arrowhead; haven’t made it there yet. Its one of our destination plans soon. We have so much to explore here in California.

Thanks again for all the tips.

Jonathan

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