Timing issue after replacing spark plugs & wires?

Pre-Strike-'71-Z/28

Striking Z/28
Aug 18, 2019
35
My Z28 is a 1971 but it has a newer 350 engine in it (maybe a late '70s). I just replaced all 8 spark plugs and wires. I put in the same brand and type that it had before from the previous owner (Accel 276S spark plugs and Accel 8mm hi-temp wires). Before the replacement I think the engine had a timing issue (it kept misfiring for a couple of seconds after being turned off). The hotter the engine was the more it would misfire. Now with the new spark plugs and wires it is more accelerated at idle speed, it now backfires through the exhaust pipes when I push the throttle, and the throttling is not as strong as it used to be (it doesn't rev up the engine as much). The gap that the old spark plugs had was somewhere around 0.032 inches. The gap that I set in the new spark plugs is 0.035 inches. Can someone shed some light on what's going on and what do I need to do to fix this? Thanks in advance!
 

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Veteran Member
Lifetime Gold Member
Mar 27, 2016
4,727
NY
You can ear time it I just loosening the distributor hold down bolt ,start the car and slowly turning the distributor One Direction if it starts running worse turn it a little the other direction so it Goes to a high idle and back it down just a bit. Or buy a timing light
 

PBZ28

Veteran Member
Nov 3, 2017
179
First I would double check your firing order. Did you change the wires one at a time? Then check your timing. If my memory is right a misadjusted carburetor and/or to fast of an idle speed can cause engine run on ( dieseling ).
 

Pre-Strike-'71-Z/28

Striking Z/28
Aug 18, 2019
35
First I would double check your firing order. Did you change the wires one at a time? Then check your timing. If my memory is right a misadjusted carburetor and/or to fast of an idle speed can cause engine run on ( dieseling ).

I tried to change the wires one at a time as much as I could but I'm thinking of two wires that I could have swapped. How can I find out my firing order?
 

Pre-Strike-'71-Z/28

Striking Z/28
Aug 18, 2019
35
You can ear time it I just loosening the distributor hold down bolt ,start the car and slowly turning the distributor One Direction if it starts running worse turn it a little the other direction so it Goes to a high idle and back it down just a bit. Or buy a timing light

Thanks. Turns out I had two wrong wires at the distributor (6 & 8). Once I swapped them the problem was gone. I still have the misfiring issue that I had before I replaced the spark plugs and wires but not as bad. It keeps misfiring for a couple of seconds after I turn the engine off.
 

Pre-Strike-'71-Z/28

Striking Z/28
Aug 18, 2019
35
I tried to change the wires one at a time as much as I could but I'm thinking of two wires that I could have swapped. How can I find out my firing order?

Thanks. Turns out I had two wrong wires at the distributor (6 & 8). Once I swapped them the problem was gone. I still have the misfiring issue that I had before I replaced the spark plugs and wires but not as bad. It keeps misfiring for a couple of seconds after I turn the engine off.
 




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