Spark Plug Ground Electrode Gone

[Scoobum]

What would cause a ground electrode on a spark plug on one of these engines to break off? Got a pic from a TR owner...and it's gone. He raced me earlier this year...and the car backfired horribly. BLM's were 142 after the run.


Forgot to mention after it backfired I found it had blown the PCV valve hose off. BLMs remained at 142 after reattaching it. He's sending me the PL file tomorrow. He says the boost spiked to 31.

[TexasT]

Detonation is a nasty force and if he was sportin 31psi I would guess that engine experienced some.

[Steve Wood]

Detonation and the resultant high cost combustion took it right off

[Forzfed]

I remember when I was injecting 20% Nitro and even though I ran C16 in the tank and it showed no knock on DS.  It still almost blew the tips off the spark plugs.

[larrym]

Would a nonprojected tip help?

[Scoobum]

I haven't had any problems with spark plugs to date...with either alky or C 16...using 43's gapped at .030.

[gusszgs]

UR-5's here gapped @ .030 no issues alky only

[larrym]

I have run both UR5s and YR5s the only difference is the YR5s are non-projected tips.


I have read that the non-projected tip can help with pre-ignition they are popular with the boosted import crowd.

[Shimy87]

I'm using 42's, should I be using 43's with my set up?

[Scoobum]

42's are for a higher boost level. You'd likely be better off with 43's. I run CR43TS...but that's just me.

[Steve Wood]

as usual, I agree with Brad.

I have to laugh when I see plug and plug gap suggestions today.  It seems that plug gaps keep getting tighter.  I have always run 0.035" for 25 psi or less and have accidentally logged 30 psi once when the hoses blew off the vacuum block without a hint of detonation.  Typically, I suggest 0.032" for boosts above 25 psi for no reason other than lots of people feel more comfortable with it.

The other day, on FB, some guy was having backfiring at 10 psi and mentioned he was gapping plugs at 0.032".  Promptly, some guy informed him that you cannot run boost on wide plug gaps like that.  He instructed him to set the gaps to 0.24" as I recall.  Several people promptly agreed with him.

I have seen several guys post that UR-5s/UR-6's are far too hot for boosted cars and others concur.

I am beginning to think we have been invaded by wannabes from a different time line.

[Shimy87]

looks like I'll get some 43's and gap em at .035....thanks again fellas