New to me 77 620

[Crashtd420]

10 hours ago, Dusten said:

I'm aware.

 

Checked the 4 plugs

5.5 Kohms

5.7 Kohms

5.4 Kohms

1.9 Mohms

 

Found the problem

That's an interesting way to check plugs. Very effective....

[datzenmike]

BPR6ES with the R for resistor. These plugs have a built in resistance to suppress radio interference. Increased resistance will lower the ability to fire.  Current flow is a function of V/R. 1.9 million ohms will reduce current to 1/4 what a 5k ohm plug will allow.

[Dusten]

55 minutes ago, datzenmike said:

BPR6ES with the R for resistor. These plugs have a built in resistance to suppress radio interference. Increased resistance will lower the ability to fire.  Current flow is a function of V/R. 1.9 million ohms will reduce current to 1/4 what a 5k ohm plug will allow.

 

 

Which is exactly why it idled fine.  Rev'd fine.  But got increasingly worse under load.  

[banzai510(hainz)]

good idea. I have never thought of ohm out the plugs

[datzenmike]

It's increasingly harder to jump the plug gap as the engine load increases.

[Dusten]

9 hours ago, banzai510(hainz) said:

good idea. I have never thought of ohm out the plugs

 

 

How else would you test them?

[datzenmike]

Rather subjective but hold against the grounded head and turn engine with starter. Visually do they all look the same?

[Dusten]

Maybe if it's almost completely failed.  But these would pull to 3500+ in third.  I really doubt you'd see a spark difference with cranking only.  

[datzenmike]

As stated, pretty subjective. If one is glaringly different then change it.

[banzai510(hainz)]

On 2/2/2024 at 5:41 PM, Dusten said:

How else would you test them?

place near ground and see if sparks with Acell SUPERCOIL.

 

be honest I havent bought new plugs in 20 years. sand blast them.

 

If plug is out its faster to put a new plug in then getting the volt meter to ohm out when all said and done

Edited February 4 by banzai510(hainz)

[Dusten]

11 hours ago, banzai510(hainz) said:

place near ground and see if sparks with Acell SUPERCOIL.

 

be honest I havent bought new plugs in 20 years. sand blast them.

 

If plug is out its faster to put a new plug in then getting the volt meter to ohm out when all said and done

 

 

I tested them to see why the repair worked.  I work in aviation. Prior to that i worked in ships out to sea.  Knowing why something failed is as important as knowing it failed.  

 

I tested them then next day before I threw them away to give myself the piece of mind id fixed it. Rather than it just running better.  

[Dusten]

As a side note I'll be cleaning the truck up over the next few days and selling it.  

 

I bought it's replacement today.  

 

[banzai510(hainz)]

I worked Aviation too.

Denmark

me on wing

Edited February 5 by banzai510(hainz)

[Stoffregen Motorsports]

Sniffing your armpit? Or just looking gangsta.

[banzai510(hainz)]

RUN DMC was BIG at the time!!!!!!!!!

[datzenmike]

Wiping nose on shoulder. Learned from bow hunting pigs on Maui with Tad Nugent

[Stoffregen Motorsports]

RUN DMC was not gansta. They were hiphop lite.