Reading the Plug

[Joe Warren]

There are many Veteran boaters here that have a ton of experience on engine mods and Go Fast stuff. But in todays world of different boats types and pipes & props that are on the market it is now ever important to be able to read the plug for Maxium Performance. If your just trying to get it running, maybe not so important? But the day will come that you want more speed and the needle changes and prop pitch and pipe length changes will all effect fuel demands and the Needle changes. In some applications we have a ever changing load. (hydro) You will want to make plug reading after comng in on the rich side of the 3rd channel needle and finding a barely clean needle & a few Wide open throttle runs..... A clean & shiney ring around the plug is Cold Operating Engine Temps. The Ring around the Element is Engine Operating Temps. However the Wire (element) can look New & Shiney, Dull, Medium Gray, Gray & Blistered. This is actually the fuel mixture the engine is operating with. Play close attention to the wire & it will tell you If you can possibly lean the engine more for speed Or if you are at the limit of damaging the plug element & engine. Small engines .15 &.21 . operate at high rpms and abuse the plugs regular. But learning to read the plug can tell you if you can possibly change props or pipe length to Go faster? A Carmel Colored Ring around the plug and a all Gray Wire is Good Needle and Good Engine Operating Temp 100% Power ... Investing in a Good Flow Meter and a small Infrared heat gun can help you learn quickly at the lake. Maybe some others will post here to tell what they have learned over the years to read the plug?

 

[Philmunsterman]

Good stuff Joe. This is a good Pic of the plug out of my SAW Eagle CMB 91 HR. If your Plug looks like this you're very close. Phil

 

[Joe Warren]

yes, when you can get the pipe to suck the element out of the plug like that... it is normally 2 staging the pipe and running very well.......... That is a hard plug to get in cold water too.......

 

[Jack ODonnell]

Good stuff Joe. This is a good Pic of the plug out of my SAW Eagle CMB 91 HR. If your Plug looks like this you're very close. Phil

The color of the threads haft way up on this plug is why the turbo seat plug are better

 

[Andy Greene]

Jack, You refer to the turbo plug seating better, I assume that means its more flush to the inside of the head button? what are the advantages/disadvantages ? Sorry if thats a stupid question.....

Andy

 

[Jack ODonnell]

Jack, You refer to the turbo plug seating better, I assume that means its more flush to the inside of the head button? what are the advantages/disadvantages ? Sorry if thats a stupid question.....

Andy

Hi Andy; As seen by the color on the threads,the combustion process is leaking into the threads. This increases the head volume, not by much, but it does.The turbo taper seat will not allow this. And no your question was NOT stupid.

 

[Joe Warren]

Good Point Jack!

 

[Terry Keeley]

What if there's no element left to read? :unsure: :lol:

 

[Andy Greene]

Jack, You refer to the turbo plug seating better, I assume that means its more flush to the inside of the head button? what are the advantages/disadvantages ? Sorry if thats a stupid question.....

Andy

Hi Andy; As seen by the color on the threads,the combustion process is leaking into the threads. This increases the head volume, not by much, but it does.The turbo taper seat will not allow this. And no your question was NOT stupid.

Thank You Jack for your response. So that said, it confirms what I thought the advantage was. Now to the next uneducated question.

What would be the advantage to the gained head volume and what (if any) tuning changes would need to be made to capitalize on the gain.

I/E mixture-pipe length - ect . Sorry just try to learn a little here for a change

I never really had considered reading the outer ring or the threads when looking at my plugs- just the element.

Andy

 

[Andy Greene]

What if there's no element left to read? :unsure: :lol:

You found the edge :lol:

 

[Jack ODonnell]

Jack, You refer to the turbo plug seating better, I assume that means its more flush to the inside of the head button? what are the advantages/disadvantages ? Sorry if thats a stupid question.....

Andy

Hi Andy; As seen by the color on the threads,the combustion process is leaking into the threads. This increases the head volume, not by much, but it does.The turbo taper seat will not allow this. And no your question was NOT stupid.

Thank You Jack for your response. So that said, it confirms what I thought the advantage was. Now to the next uneducated question.

What would be the advantage to the gained head volume and what (if any) tuning changes would need to be made to capitalize on the gain.

I/E mixture-pipe length - ect . Sorry just try to learn a little here for a change

I never really had considered reading the outer ring or the threads when looking at my plugs- just the element.

Andy

Andy; If the pipe is the right length & volume, most of the time you will need to increase the head volume. This is because the pipe is packing more fuel & air into the cylinder,if you dont you will end up like Terry was talking about.

 

[Jack ODonnell]

What if there's no element left to read? :unsure: :lol:

Been there many times !!

 

[brad nichols]

There is a good article in Namba Prop Wash this month on reading the plug.

Brad

 

[Joe Warren]

What if there's no element left to read? :unsure: :lol:

Your boat has been renamed DEAD WOOD!!!!

 

[bjacobsen71]

Just a quick question here, sorry it is a bit off topic but what is meant by the term "two staging the pipe"? I've heard the term a few times here but am unfamiliar with it.

Thanks.

 

[Brian Sorgente]

What about when the element is pulled to one side of the plug? Can you determine something about your setup if the element is pulled toward the boost port vs the exhaust or transfers?

Brian

 

[Joe Warren]

Just a quick question here, sorry it is a bit off topic but what is meant by the term "two staging the pipe"? I've heard the term a few times here but am unfamiliar with it.

Thanks.

Brett as the boat comes to Maxium RPM and unloades the pipe or expansion chamber goes into Resonance. At this time there is added increase of power. There are 2 and sometimes 3 times this can happen. but many things must be correct for it to happen at all. Many of todays Marine engines have Good timing numbers. You just have to find the correct pipe and pipe length and prop to get it all to work.

 

[bjacobsen71]

So is this the same as finding the right pipe length for the conditions/setup or is this somthing that happens at a different rpm range than the primary tuning? I understand the operation of tuned pipes, I am just not familiar with the terminology, ie. is it the same as the engine getting "on the pipe"?

 

[Ronald Van Wagnen]

" Maverick" was an old two cycle Karting term we used. Not only could you hear it happening but it was felt in the seat of your pants as you went by the competition on the main straight !

 

[Richard H. Parshall jr.]

So is this the same as finding the right pipe length for the conditions/setup or is this somthing that happens at a different rpm range than the primary tuning? I understand the operation of tuned pipes, I am just not familiar with the terminology, ie. is it the same as the engine getting "on the pipe"?

It's more like the engine gets on pipe then it's like it gets on pipe again

Sounds a lot like when an on road car goes into second gear

then its like running clean then hitting the powerband on a dirt bike i assume...?