Help picking spark plugs.

[bucket]

For those who have problems with plugs lasting a long time: How do they fail? Eroded electrodes, oil-fouled?

In my experience, Bosch platinum plugs (single electrode) last a long time with GM HEI distributors --either stock or with MSD module & coil. I have no idea why they wouldn't work for any Chevy ignition. I'm currently running basic NGK plugs in a 355 with GM Vortec heads, and they also work fine. And their plated bodies don't rust like AC and Autolite.

Also, it's worth mentioning again that there are different "reach" plugs, which is the length of the threaded portion. Also, either tapered or gaskets seats. Not a problem when using the exact AC plug specified for a stock engine, but can be a problem with aftermarket heads.

As far as the Bosch Platinum plugs go, usually they were a little eroded but looked ok otherwise. The big issue was usually misfire codes causing the engine light to pop on. Sometimes isolated to specific cylinders, but often just the P0300 random multiple misfire code. Many many times, just swapping in a different brand of plug took care of the issue.

 

[idahovette]

We had the same problem in our shop. Put Bosch in a GM and a week or two later , it's back with CEL on. Went to the proper AC plugs and the problem was gone

As far as the Bosch Platinum plugs go, usually they were a little eroded but looked ok otherwise. The big issue was usually misfire codes causing the engine light to pop on. Sometimes isolated to specific cylinders, but often just the P0300 random multiple misfire code. Many many times, just swapping in a different brand of plug took care of the issue.

 

[84-C20]

For those who have problems with plugs lasting a long time: How do they fail? Eroded electrodes, oil-fouled?

In my experience, Bosch platinum plugs (single electrode) last a long time with GM HEI distributors --either stock or with MSD module & coil. I have no idea why they wouldn't work for any Chevy ignition. I'm currently running basic NGK plugs in a 355 with GM Vortec heads, and they also work fine. And their plated bodies don't rust like AC and Autolite.

Also, it's worth mentioning again that there are different "reach" plugs, which is the length of the threaded portion. Also, either tapered or gaskets seats. Not a problem when using the exact AC plug specified for a stock engine, but can be a problem with aftermarket heads.

I'll try to answer. At the shop we tend to see vehicles with #1. excessively worn or fouled plugs causing misfires. #2. autolite and bosch plugs, nothing visibly wrong with the plugs just not firing. I have no idea why, just what I've seen.

 

[DoubleDingo]

As far as the Bosch Platinum plugs go, usually they were a little eroded but looked ok otherwise. The big issue was usually misfire codes causing the engine light to pop on. Sometimes isolated to specific cylinders, but often just the P0300 random multiple misfire code. Many many times, just swapping in a different brand of plug took care of the issue.

I installed Bosch plugs into my Jeep on either the first second tune-up after I bought it '02. It developed a rough running condition that I couldn't track down. Pop said spark plugs. Changed the plugs to Autolite and the rough running condition cleared up.