#2 cylinder not firing

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Jun 4, 2006 | 04:15 PM

Jansenwins

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From: Bettendor Iowa

#2 cylinder not firing

1985 L98, cam, heads, intake swap, and carb conversion. Any ideas why #2 cylinder doesn't appear to be firing. I've changed plugs, plug wires, coil, distributor, etc. There is spark from the plug wire but after running the engine and removing the plug from #2 it looks like it hasn't been firing?????? All other plugs look fine.

Thanks....this has me baffled!

Jun 4, 2006 | 05:25 PM

anesthes

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From: Salem NH

Quote:

Originally Posted by Jansenwins

Cyl blown? do a leakdown and compression test.

Plug just soaked with fuel?

-- Joe

Jun 4, 2006 | 06:03 PM

Corvette Kid

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From: Good health is merely the slowest possible rate at which one can die

St. Jude Donor '04-'05-'06-'07

Have you checked that injector and it's wiring? If they check out and you have spark, you've got a bad cylinder. If a cylinder is bad enough to be a dead miss, you should have lots of blow-by unless it's a burnt or bent valve. A simple compression test should tell the tale either way.

Jun 4, 2006 | 08:58 PM

Jansenwins

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From: Bettendor Iowa

OK...I turned the engine over without the plug ...did this while putting my finger in the plug hole. I did the same thing with cylinder number 4 so as to have a comparison. The #4 cylinder nearly blew my finger out of the hole....number 2 had very little air comin out of the spark plug hole. Big, big difference between the two cylinders.

So now what guys? What are the possible reasons for this? How do I check for blow by? The plug looked like it came right out of the box....not wet with fuel and no signs of oil. Do I assume it has to be the piston/rings or could it be something else? Where is the air going as the piston is coming up cuz it sure isn't building compression?

Thanks in advance.

Jun 4, 2006 | 09:30 PM

Corvette Kid

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From: Good health is merely the slowest possible rate at which one can die

St. Jude Donor '04-'05-'06-'07

Quote:

Originally Posted by Jansenwins

Well at this point it really doesn't matter because at best, that head's going to have to come off. But this thing still runs, right? With it running, remove the oil cap. If it's puffing out of there like an old steam engine, it's a cylinder problem. If not, it's a valve problem. Either one can cause a loss of compression. A valve problem is the best case scenario. You can pull the heads off, have the damaged valve replaced and get a valve job and all will be well. If it's blow-by in the cylinder, you're looking at an overhaul.

Jun 5, 2006 | 09:27 AM

mudslide

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From: north branford ct

Also check the cam you put in--make sure the lobs are ok in that cyl.

Jun 5, 2006 | 11:05 AM

rick lambert

Le Mans Master

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From: seattle WA

I'd pull the valve cover on that side and watch the lifter action. If it looked right in comparison with the others..then I'd do the compression test.

Jun 5, 2006 | 11:08 AM

Pete K

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Misajusted rockers(too tight) will cause little or no compression. Reajust them before serious disassembly.

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Jun 5, 2006 | 12:04 PM

hip

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:iagree lifter may be too tight, pushrod could be bent, lifter could have come out of bore.are head bolts tight. look for the simple things first

Jun 5, 2006 | 10:30 PM

#10

anesthes

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From: Salem NH

Quote:

Originally Posted by rick lambert

I'd pull the valve cover on that side and watch the lifter action. If it looked right in comparison with the others..then I'd do the compression test.

Agree! Check the rockers, pushrod, lifter, cam action..Last season I had a polylock come loose, and the pushrod bent and the rocker jumped away. Thought I lost a cyl.. trailered the car home, yanked the valve cover to see if my valve was bent. said "wtf".. replaced the pushrod, adjusted lash and made another 40 or so passes until the motor exploded. (from a lean condition under 13lbs of boost)

-- Joe

Jun 6, 2006 | 08:40 AM

#11

Jansenwins

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From: Bettendor Iowa

Thanks for all the replys and help!

Well, I hate to admit it cuz I am meticulous in my settings....but, I made a mistake on that cylinder when I installed the roller rockers. Had them adjusted wrong and the intake valve wasn't closing properly.

Made the adjustment and the cylinder builds good compression. Amazingly the plug fires, and even better yet, the increase in power is pleasing to my fanny!