Glow Plugs

[Kevin_R_Clark]

OK, time to learn some more! I understand the heat ranges and the effect they have, essentiallly somewhat controlling ignition timing. My question is, does a brand new plug preform better than say one that has 20 runs on it. Assuming the used one has no visible damage. Not that I could afford to burn a new plug every heat, but is it good practice to use a new one when it is on the line or does it just depend on the characteristics of each particular engine. Another question, I have a K&B 7.5 Goldhead outboard running 50%. It does not hurt plugs even if I make a lean run and it quits. Does this mean I need to bring the head clearance down. Oh_yeah MC-9`s. Up till now I just thought it was a good thing that it didn`t burn plugs. Now I am thinking I am probably missing out on some performance.

 

[nitrotoys]

As a sport boater, I ran plugs untill they went bad.

Dont know about the racers, I do have one plug that came with cmb ob motor thats lasted about 2 gals.

I tried a new plug (R5) Plug and didnt run as well as with stock plug.

so put it back in.

You go through enough plugs, dont need to change when not bad.

tom

 

[ScottVanSlooten]

When I'm racing I change plugs every heet and then go back and use them when we are at the play pond . Yes it does make a differents in racing because if you die with an old plug you may as well kick your self in the nuts if you don't find any thing else wrong with the motor . Scott

 

[akilbar]

Same as Scott, I run new every heat then drop them in a padded box to use at the test pond later.

Works for me, and I run 2 boats with twin plugs, thats a bunch...

 

[snowdog-2112]

Here's a trick I learned some time ago.

If you are going to change plugs often, as in a race, be sure to "burn" your plugs in prior to. This not only strengthens the coil, buts lets you know if the plug is good. Though not common, I have seen a racer or two replace their plugs during start time and despite the plug being new, it was bad...makes for extra stress during a race.

Snowdog

 

[Watercadet]

I must be that racer who had the bad plug! I race off road a lot and more than once (twice infact) I have gon into the main with a brand new plug that would break or just up and quit. Nothing had changed with the settings or the atmosphear, they just wanted to go bad. That was 2 out of many but I now start out a race day with a new os 8 and run it all day. My motors take such good care of their plugs that I have several "practice" plugs In short I don't see a peformance drop where I am racing and I like the tryed and true feeling at the start buzzer.

 

[Joe_Knesek]

I used to change my plugs after every heat until I started going to races with Stan Simpson. Stan's thinking is that you inspect the plug after every run but you run the same plug until it shows signs of wear. He's a multi time US1 winner and I tend to agree with him.

The fact is, nobody knows when a plug is going to fail but everyone knows that they fail most often when you run the motor too lean. Even a new plug will not cure this problem.

Last year at a race in London, I ran the same plug in 8 heats. I inspected the plug each time my son and I ran the boat and it had no damage. The boat ran just a fast in the 8th heat as it did in the 1st.

 

[Rules]

Back eons ago, when my club was running strong, I would poll each member for the number of plugs he would need for the season. I would call other non-racers and get their plug orders also, then buy in bulk, direct from McCoy. Many years I would get near 2000 plugs, which included about 300 for backup for unknowns. This gets the price way down when you are real serious about winning, running for hours doing setup with hull and props. Did the same with fuel with custom mix in barrels. Back then the only plug the LHS carried was K&B and Fox, and his fuel was 15%! Worked for us.... John in Huntsville

 

[mcripps421]

Hello there fellas,

What difference does the plug heat make? I currently run a CMB 6 plug. I run 25% nitro and am in the uk. What plug should i be using, heat wise?

thanks

Michael Cripps

 

[boaterbill]

Michael,

K&B 1L should work for you, I usally run K&B HP 60% nitro. McCoys are highly overated not to mention Pricey. IF I remember correctly there is only one company out there that makes all the plugs! Correct me if I'm wrong?

 

[TimD]

I've heard that about the plugs made in the USA before. Is it correct?

Michael,

The plug heat range is generally a case of the colder plugs have a heavier / thicker element. General rule of thumb is that if you take the ignitor off the plug and the idle drops dramatically the plug is too cold for it. Really hot plugs are great for idle but if the motor and pipe are working well it tends to damage the thin elements. Compression has a dramatic effect on plugs also.

There is no substitute for testing unfortunately. If you are happy with the current plug you are using, try 1 range hotter and 1 range cooler and see whether there is any difference.

Tim.

 

[apache5056]

What's a good plug and who has the best price on them...

MAC21.... B mono... IMPBA.

 

[Watercadet]

Hey Bill I thought that it was McCoy making all of the plugs..

 

[nitrotoys]

Wayne,

I ALWAYS ran R5 os race plugs in the mac with good luck, on 40% redmax.

its a expensive plug, but seemed to last for me.

I tried A5 worked pretty good, seemed the R5 kept a needle better.

Tom

 

[DaveMarles]

Conelock plugs for me in all engines. Novarossi C5TF to C7TF.

Dave

 

[Bob Kensill]

I run nothing but McCoy #9 plugs in all my nitro boats. I pull the last coil down and pre-heat the plug. I never run too lean and don't take out plugs. By the way,there is no better place to get your McCoy plugs than at Phils Hobby Shop.

 

[TimD]

Shameless plug Bob? (pardon the pun!)

 

[Ron Olson]

Phil's does sell a lot of plugs! Great place to buy Red Max fuel from also. I don't know about their prices on cone-lock plugs but maybe Bob can help. My kid found one site, www.rc-mushroom.com that has the best prices that I've seen on them.

 

[Joe_Knesek]

Conelock plugs for me in all engines. Novarossi C5TF to C7TF.Dave

Same here on my 20 motors. Bill McGraw has good prices.

 

[Don Ferrette]

Bill McGraw has best prices on quantity purchases of plugs. And I don't work there.......