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Discussion Starter · #1 · (Edited)
I recently rebuilt the motor in my 1981 280zx N/A and upon startup i had a severe lack of power which i fixed but now whenever the car idles it pops out the exhaust manifold (it only has headers on it currently). this popping gets worse whenever it drives. (the higher the rpm the faster the popping gets). for reference the car upon startup jumps to 2k rpm and slowly lowers itself down to 1k rpm and stays idling. Any help is appreciated

Edit*
After messing with timing the Car doesn't pop anymore when you give it gas at the recommended 10 degrees BTDC the only downside is the car barely stays running at around 250 rpm (sounds like its only running on 2 cylinders). This vastly different when you set the timing to 15-20 degrees BTDC and hit the gas which causes the car to backfire out of the exhaust but run on all 6 cylinders at about 1k rpm
 

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Do you know which cylinder is causing the issue? With the car running, remove one spark plug wire at a time from the distributor cap an see if you can pinpoint the misbehaving cylinder.

check your valve lash.
a bad plug or plug wire
a cracked distributor cap
incorrect firing order

A lean condition can cause backfire.
Ever have your lawn mower or go cart or snow blower run really bad and it ran better with the choke on? That is caused by a really lean condition.
 

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Discussion Starter · #4 ·
First, look at whatever work you just did and see if there's a flaw there. What did you do to improve power?

Next, check timing, plug wires, cap & rotor.
Car wasn't getting spark to cylinders 4, 2, 6 fixed by replacing spark plug wires. timing is weird when i adjust the distributor to 20 BTDC it idles great and on all cylinders but stack fires when i adjust it to 10 BTDC like the car wants it idles at 500 rpm and sounds like its only running on 2 cylinder but when you hit the gas all cylinders jump back to life and it no longer stackfires.
 

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8 / 71 240Z, HLS30-40031, L24-052899, Sunshine Yellow
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Stackfire is a managed service provider (MSP) and security services specialist.
Or maybe an industrial chimney fire. The most obvious sign of a chimney fire is when you see flames and sparks shooting out of the chimney like a Roman candle on the Fourth of July.
Locomotive turbo fire Train stack fire
(120) Locomotive turbo fire Train stack fire - YouTube
 

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Discussion Starter · #6 ·
Stackfire is a managed service provider (MSP) and security services specialist.
Or maybe an industrial chimney fire. The most obvious sign of a chimney fire is when you see flames and sparks shooting out of the chimney like a Roman candle on the Fourth of July.
Locomotive turbo fire Train stack fire
(120) Locomotive turbo fire Train stack fire - YouTube
i thought Stackfire means pops and bangs coming out of your exhaust and backfire is when its coming out of the carbs/intake manifold is there another definition of word implying pops and bangs out of exhaust
 

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Discussion Starter · #11 ·
Is your vacuum advance hose disconnected when you are adjusting the timing? Is the hose connected to manifold vacuum or ported vacuum (throttle body)?
hose connecting to the vacuum advance is disconnected when timing is being adjusted and the hose is connected to the throttle body. Something i noticed is when i set the Car is set to 10 degrees BTDC it barely idles but it no longer backfires when the gas is pressed and when i set the car to about 15-20 degrees BTDC it idles and runs great but backfires out the exhaust.
 
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