Carburator all black inside
Thread Starter
Burning Brakes
Joined: May 2010
Posts: 941
Likes: 10
Carburator all black inside
I have a 74, L48, 4 speed I am doing a resto on this winter. Finally got under the hood and notice that the Holley List 4777-3, 650 cfm double pumper is all black inside. Its not wet oily black, nor is it soot. I suspect carbon, it will clean off with a brush and carb cleaner.
Other than the black in the carb, the engine runs perfect, instant start, great idle, plenty of power for a L-48. The Edlebrock Performer intake is as clean inside as a new one. The spark plugs are a beautiful tan, PCV is clean and functioning properly.
Any idea what the cause of the black inside the carb might be ?
I bought this Vette late fall last year. Its also possible that someone put this carb on, from another engine in the present black condition....dont know.
Thanks
8Valve
Other than the black in the carb, the engine runs perfect, instant start, great idle, plenty of power for a L-48. The Edlebrock Performer intake is as clean inside as a new one. The spark plugs are a beautiful tan, PCV is clean and functioning properly.
Any idea what the cause of the black inside the carb might be ?
I bought this Vette late fall last year. Its also possible that someone put this carb on, from another engine in the present black condition....dont know.
Thanks
8Valve
Last edited by 8valve; Jan 21, 2017 at 03:23 PM.
Thread Starter
Burning Brakes
Joined: May 2010
Posts: 941
Likes: 10
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,178
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From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
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since its an unknown to you, i would say clean it and run it and see if it comes back. All I can think is the pcv valve is sucking oil possibly, but you say it isnt oily, so it is weird
Thread Starter
Burning Brakes
Joined: May 2010
Posts: 941
Likes: 10
I cant do a lot of engine running as we are in deep winter, Vette is on the Kwik Lift and deep snow outside. So any real testing wont come to spring.
With that said, I looked everything over again this morning and have come to this diagnosis;
I believe the Carb came off another engine that was suffering with Back Fires, thus the black carbon. If this black carbon had happened on this engine, then the inside of the Edelbrock Performer intake would also be black, it is as bright and clean as a new intake manifold. Some past owner took this carb off a back firing engine and put it on this engine....thats my best guess. If after a few hundred mile this summer it stays clean, we know this engine was not the problem.
8Valve
Thread Starter
Burning Brakes
Joined: May 2010
Posts: 941
Likes: 10
What do you attribute the black in your carbs in relating to the big cam ?
8Valve
Melting Slicks
Joined: Feb 2006
Posts: 3,105
Likes: 96
From: Sunrise FL
Gets worse with age of the engine, with worn rings, valves.
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1st Gear
Joined: Oct 2019
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I have a 74, L48, 4 speed I am doing a resto on this winter. Finally got under the hood and notice that the Holley List 4777-3, 650 cfm double pumper is all black inside. Its not wet oily black, nor is it soot. I suspect carbon, it will clean off with a brush and carb cleaner.
Other than the black in the carb, the engine runs perfect, instant start, great idle, plenty of power for a L-48. The Edlebrock Performer intake is as clean inside as a new one. The spark plugs are a beautiful tan, PCV is clean and functioning properly.
Any idea what the cause of the black inside the carb might be ?
I bought this Vette late fall last year. Its also possible that someone put this carb on, from another engine in the present black condition....dont know.
Thanks
8Valve
Other than the black in the carb, the engine runs perfect, instant start, great idle, plenty of power for a L-48. The Edlebrock Performer intake is as clean inside as a new one. The spark plugs are a beautiful tan, PCV is clean and functioning properly.
Any idea what the cause of the black inside the carb might be ?
I bought this Vette late fall last year. Its also possible that someone put this carb on, from another engine in the present black condition....dont know.
Thanks
8Valve
