Engine miss

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Jun 14, 2020 | 10:54 AM

Steve Kistler

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Racer

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From: Oklahoma

Engine miss

Thought I heard a miss this morning so hooked up timing light. Noticed that at idle every few seconds the timing mark would jump btdc and the engine is running a little rich. I have all new plugs,wires,distributor carburetor,etc.No known vacuum leaks. Thoughts? I also was pulling off plug wires one at a time and did not here a difference. I used my spark tester and all plugs getting spark. I should be able to hear a difference when wire is removed I think

Jun 14, 2020 | 11:39 AM

MelWff

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If the miss is only at idle, have you adjusted the idle mixture screws?
Are you totally stock or any modifications?

Jun 14, 2020 | 03:23 PM

Steve Kistler

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Racer

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From: Oklahoma

480/288 cam 600 Edelbrock carb bored .060 on a 350. No smog or cats Did mess with mix and almost all the way lean but no change

Last edited by Steve Kistler; Jun 14, 2020 at 03:47 PM. Reason: More information

Jun 14, 2020 | 04:52 PM

HeadsU.P.

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From: Cool Northern Michigan

Take the timing light false firing, with a grain of salt. Most lights will do that. Its miscommunication between the light and the HEI.

The removal of one plugwire should be noticeable on your tach, but not always noticed with a keen ear.

Jun 14, 2020 | 05:36 PM

Steve Kistler

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Racer

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From: Oklahoma

I have a bad ear from rock and roll and shooting guns. Never really sure what I hear but always second guessing everything even when it seems to be running pretty good. Excellent throttle response and get a really good squall on a first to second shift.

Jun 14, 2020 | 05:53 PM

HeadsU.P.

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From: Cool Northern Michigan

Re-reading post one. New plug wires.
Just for the hell of it, trace plug-wires 5 & 7 from the cap to the plug. At no point should those two be close together. When they come to a loom, separate as far as possible from each other.
Chevys firing order, makes a "Crossfire" easy with those two cylinders.

Then you can rock-on.

Last edited by HeadsU.P.; Jun 14, 2020 at 05:54 PM.

Jun 14, 2020 | 06:19 PM

Bikespace

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What are you using to measure your rich running condition?

I'd start with the most obvious. Is your vacuum advance hooked up to manifold, or ported, vacuum?

Jun 15, 2020 | 09:45 AM

Rescue Rogers

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You should have an rpm change when any plug wire is disconnected. You can turn down the idle speed as low as you can and have it run smooth, then try one wire at a time. If they seem not to matter and the problem seems to keep changing symptoms check your distributor caps wear pattern. I had the bushing break that was where the retainer clip went that kept the shaft from riding up. In the beginning it was just at certain rpms then as the rotor ate into the cap it got worse....it’s something you can check and easily eliminate. Also a club member also just posted a video of a 2 piece distributor separating the shaft somewhere internally. He had the bottom in a vise and could still twist the rotor around by hand with a lot of force. The oil pump pin was still installed and not sheared

Last edited by Rescue Rogers; Jun 15, 2020 at 09:47 AM.