high rpm backfire
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
high rpm backfire
Guys I have a question, my car runs good idles good but when I get down on it will backfire out the exhaust when the carb goes on the back 2 barrels. It`s a 383 with a 600 holley and edelbrock manifold. I a thinking it`s to lean on the back side of the carb. I replaced the points with a Pertronix 3 and the rev limit is set at max and my timing is dead on the money. Just cruising around it is no problem but when I wind it up and go through the gears it will backfire. Any suggestions?
Melting Slicks
Joined: Jul 2006
Posts: 2,268
Likes: 480
From: Salmon Arm, BC
Seems like you need to pull the rear float bowl and see if there is something blocking the fuel flow, have a look at the metering block as well and make sure the jets and passages are clear. From your description it sure seems like your getting lots of air flowing but not enough fuel.
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
Seems like you need to pull the rear float bowl and see if there is something blocking the fuel flow, have a look at the metering block as well and make sure the jets and passages are clear. From your description it sure seems like your getting lots of air flowing but not enough fuel.
Le Mans Master
Joined: Feb 1999
Posts: 8,351
Likes: 75
From: Tampa Bay FL
Guys I have a question, my car runs good idles good but when I get down on it will backfire out the exhaust when the carb goes on the back 2 barrels. It`s a 383 with a 600 holley and edelbrock manifold. I a thinking it`s to lean on the back side of the carb. I replaced the points with a Pertronix 3 and the rev limit is set at max and my timing is dead on the money. Just cruising around it is no problem but when I wind it up and go through the gears it will backfire. Any suggestions?
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
Popping out the exhaust at higher rpm is usually too much ignition advance. You can easily test this by running the engine in neutral up the rpm range. If it exhibits the popping in an unloaded state, take some advance out of it.
Unless you have done something to the carburetor, I doubt you find this to be a fueling issue.
Unless you have done something to the carburetor, I doubt you find this to be a fueling issue.
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
Popping out the exhaust at higher rpm is usually too much ignition advance. You can easily test this by running the engine in neutral up the rpm range. If it exhibits the popping in an unloaded state, take some advance out of it.
Unless you have done something to the carburetor, I doubt you find this to be a fueling issue.
Unless you have done something to the carburetor, I doubt you find this to be a fueling issue.
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Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
New plugs, wires and boots. This is a brand new engine I just built I am going to swap out my old Edelbrock performer carb and see if that gets rid of it but I don`t like it because the fuel in the bowl gets so darn hot even with an insulator plate it boils in the bowl and the Holley is a different design and the fuel doesn`t get so hot.
Last edited by Skip Burney; May 27, 2014 at 10:25 AM.
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
1) Cracked distributor cap
2) Worn plug wires
3) Loose coil wiring
3) Broken valve spring(s)
4) Prob with carb's enrichment circuits
Start with the easy stuff.
Le Mans Master
Joined: Aug 2006
Posts: 7,411
Likes: 1,551
From: mount holly NC
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Hope it's this easy.
If so adjust your idle mixture screws.
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
Thread Starter
Burning Brakes
Joined: Jul 2008
Posts: 914
Likes: 10
From: Brooklet Ga.
now that could be it I used the old stock coil, I am checking the float height and metering block in a few minutes