C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette
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Old May 13, 2018 | 06:50 PM
  #1  
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Default Back fire

changed intake manifold and carb
carb in street demon and edlbrock intake

when car is idling good and runs not bad but when i step on the gas it back fires. .it hesitates and the back fires any ideas timing is at 8 degease i am going to check to make sure my plug wires are corect
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Old May 13, 2018 | 07:04 PM
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I will throw some ideas at ya.
Lean condition?
Intake gasket not sealed 100% at the heads.
Carb base gasket not sealing.
Vacuum port fittings did not get thread sealant when installed.
Vacuum hoses to carb are loose.
Number 5 & 7 plug wires too close together.
Carb needs richer adjustments / tuning.

Last edited by HeadsU.P.; May 13, 2018 at 07:06 PM.
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Old May 13, 2018 | 11:29 PM
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Backfire up through the carb is a sign of a lean condition, caused either by vacuum leaks, or by the carb being too lean (most likely). Carb lean condition can also be caused by a lean pump shot.

Contributing to this is your retarded timing. Get some timing into that thing!...

Lars

Last edited by lars; May 13, 2018 at 11:30 PM.
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Old May 14, 2018 | 08:22 AM
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read Lars' paper on timing

Last edited by Rescue Rogers; May 14, 2018 at 08:23 AM.
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Old May 14, 2018 | 01:30 PM
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Accelerator pump linkage adjustment needs to be checked. Any slack in the arm will cause this.
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