Backfiring after new plugs installed

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

JamesMilk

Full Access Member
Joined
Oct 21, 2022
Posts
73
Reaction score
84
Location
Athens, Alabama
First Name
James
Truck Year
1978
Truck Model
C20
Engine Size
350
Hello,

I'm a new member, but the first repair I have done to her(still need to name her), was changing the spark plugs. I got the old ones out and she needed new plugs so bad(see attachment below). Put in some double iridium plugs from Bosch. And after I relubed the plugs with the silicone jelly and plugged everything back in, only one side of the head is backfiring in the muffler. Still need to find out if im running just slightly lean to have this happen, or if some wiring needs to be replaced. I did notice one of the plugs was drenched in fuel when I removed it. Maybe 1 cylinder isn't sparking off... anyways if y'all have any experience with this, I would love to learn! Google gives bad advice!
 

Attachments

  • IMG_20221021_145247_01.jpg
    IMG_20221021_145247_01.jpg
    230.5 KB · Views: 75

JamesMilk

Full Access Member
Joined
Oct 21, 2022
Posts
73
Reaction score
84
Location
Athens, Alabama
First Name
James
Truck Year
1978
Truck Model
C20
Engine Size
350
I will recheck wiring positions, and update what I find. Thought I put them all on correctly, but i did do the right side 1 at a time and the left all at once, so that may be the issue.
 

MrHorsepowerLSx

Full Access Member
Joined
Jun 25, 2021
Posts
282
Reaction score
609
Location
New Jersey
First Name
Jeffrey
Truck Year
1979
Truck Model
K35
Engine Size
454
Popping the hood and looking at the motor the cylinders will go like this……..
Note: cylinder 1&2 are going to be the closest to the accessory drive

Drivers side cylinders goes as follows
1-3-5-7

Passenger side cylinder goes as follows
2-4-6-8

Find the number 1 position on your distributor cap and bring that plug wire to the first cylinder on the drivers side. Then start running your plug wires one at a time in a CLOCKWISE motion 1-8-4-3-6-5-7-2

You must be registered for see images attach
 

JamesMilk

Full Access Member
Joined
Oct 21, 2022
Posts
73
Reaction score
84
Location
Athens, Alabama
First Name
James
Truck Year
1978
Truck Model
C20
Engine Size
350
Popping the hood and looking at the motor the cylinders will go like this……..
Note: cylinder 1&2 are going to be the closest to the accessory drive

Drivers side cylinders goes as follows
1-3-5-7

Passenger side cylinder goes as follows
2-4-6-8

Find the number 1 position on your distributor cap and bring that plug wire to the first cylinder on the drivers side. Then start running your plug wires one at a time in a CLOCKWISE motion 1-8-4-3-6-5-7-2

You must be registered for see images attach
Soo....

It seems I did swap a few cables that were cables on the left side... lol. 4&2 we're swapped and so was 6&8. Suprised it started tbh.
 

DanMcG

Full Access Member
Joined
Jun 28, 2014
Posts
1,076
Reaction score
1,891
Location
Central NY
First Name
Dan
Truck Year
1978 1985
Truck Model
k10 k10
Engine Size
400 350
Good news, now onto the next problem!
And as an old timer, can ya tell me what is silicone jelly?







/
 

MrHorsepowerLSx

Full Access Member
Joined
Jun 25, 2021
Posts
282
Reaction score
609
Location
New Jersey
First Name
Jeffrey
Truck Year
1979
Truck Model
K35
Engine Size
454
Silicone jelly is really called Dielectric Grease, it’s purpose is to Protect electrical connections and wiring from salt, dirt and corrosion. It helps extend the life of bulb sockets. It Prevents voltage leakage around any electrical connection, it can also prevents spark plugs from fusing to boots.
You must be registered for see images attach
 

Latest posts

Forum statistics

Threads
43,935
Posts
946,042
Members
35,982
Latest member
jake26104
Top