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I'm stumped, need your advice guys

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Internal Combustion
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Joined: Tue Jan 11, 2022 5:17 pm
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I'm stumped, need your advice guys

Post by Internal Combustion »

I'm writing for a friend,

He has a 4.3 L V6 Vortec engine with Edelbrock 500cfm carb, HEI ignition , dual exhaust .
Problem is, he hears a loping sound at idle . When touching the exhaust tips, the passenger side has a noticeable pulsing feel to it, where the other side doesn't have that feel to it .

He checked the # 2, 4 and 6 plugs and found # 6 plug was wet with fuel and no sign of combustion on that plug . This is a new rebuilt engine on a project car. He checked the plug wires for continuity and even got that #6 plug to spark while unscrewed laying near a ground source .
While engine was running, he unplugged #6 wire and RPM dropped maybe 200 RPM . Same results after replacing # 6 plug with a brand new one .

It seems like when screwed into the head, the #6 plug is not igniting for some reason .

Anybody have any ideas what could cause this situation ??

Thanks
dannobee
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Re: I'm stumped, need your advice guys

Post by dannobee »

Does it have the flat, crab style distributor cap? They'd crossfire internally and cause a misfire that is hard to trace.
PackardV8
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Re: I'm stumped, need your advice guys

Post by PackardV8 »

Internal Combustion wrote: Tue Jan 11, 2022 5:54 pm I'm writing for a friend,

He has a 4.3 L V6 Vortec engine with Edelbrock 500cfm carb, HEI ignition , dual exhaust .
Problem is, he hears a loping sound at idle . When touching the exhaust tips, the passenger side has a noticeable pulsing feel to it, where the other side doesn't have that feel to it .

He checked the # 2, 4 and 6 plugs and found # 6 plug was wet with fuel and no sign of combustion on that plug . This is a new rebuilt engine on a project car. He checked the plug wires for continuity and even got that #6 plug to spark while unscrewed laying near a ground source .
While engine was running, he unplugged #6 wire and RPM dropped maybe 200 RPM . Same results after replacing # 6 plug with a brand new one .

It seems like when screwed into the head, the #6 plug is not igniting for some reason .

Anybody have any ideas what could cause this situation ??

Thanks
I tell the customer we'll troubleshoot after he's installed new cap, rotor and plug wires. That fixes most ignition-related problems.
Jack Vines
Studebaker-Packard V8 Limited
Obsolete Engineering
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