Plug Readings on N20, Plug Heat Range, etc.

[procharged 79]

I don't know shit about N2O, but I just wanted to show ya a little love by saying, I hope your motor aint hurt and you can get that bad boy back out there and bust off a 7.

Good luck to ya and let us know whatchya see with the scope.

[ATVracer]

Anytime we took the strap off of a AR plug the motor was hurt.
We get away with it sometimes with the NGK's but never with an Autolite.

[onefast68]

my bet is a lifted ringland...i did the same thing at the last BOB race when the weather got good,,actually broke some of the ring off...i have read you cant pull more than 20degrees on a 7al box so check that out fofo before you try to pull more timing...i dont have any of those fancy sensors though..just learning thru the years.LOL

[Scottyk]

Im sure you have already but dont forget your valve lash.. Sounds like it running good, good luck with getting it in the 7's its close!!

[fofo]

Thx to all for the comments...the YB is the best to learn & share info for sure!

Plugs: I will seek advice from SJ & my engine tuner with regard to changing plugs or not, but I will go to a colder plug like a Autolite 3921 or NGK 11 or 12;

Valve Lash: I am a Nurd about this, but we check Valve Lash just about every time we go to the track, and had just checked it before these last few passes;

Maximum Retard: Excellent point, Will. I am now at @ 36* Motor so the 16* I am at on both stages is the max I can take out. So, I made a note to bring the Motor to 34* with 1st stage @ 24* & 2nd stage to 14* (i.e. 2* more retard). I also need to lower the 2nd stage FP.

Mystery: After again looking at all of the Plugs, and they are grossly Rich with NO HEAT (except missing strap on #2), I am convinced that we were indeed Rich, and likely have a lifted Ring Land on #2. BUT BUT BUT, why NO COMPRESSION at all is one mystery, and why did we burn the Plug strap if the other Plugs have very little Heat? I hope to report back more later tonight...gotta work during the day to PAY for this addiction...hehehe.

Troubleshooting: I am still hopeful we have a valvetrain issue vs. a burnt Piston, i.e. a broken valve spring, bent valve, or piece of the Plug strap under the valve, or whatever that caused a complete loss of compression on #2. I will also check the N20 & Fuel Jets in #2 to make sure they match the other cylinders (24f/28n, 26f/32n).

We'll fix whatever it is, and be back at the track, cause that is what Racers do...

Many thanks again!

[onefast68]

its 3931 fofo..i use the 3932 with more juice than you..and i am at 12degrees total with 2 32n kits with 18degree heads.let me know what u find.

have you checked the timing retards to make sure they are activating?

[jonesy1]

Originally Posted by fofo

Well we ran a Best 8.01 @ 171 @ 3400# today on a 29.5 tire, and everything seemed perfect on the tune-up. The track was a bit slicked so we swapped the 1st & 2nd stage with the smaller 2nd stage coming on 1st & the bigger 1st stage coming on second .8 seconds out. 1.27 3.40 5.16 140 6.69 8.01 171 (Been 1.25 on bigger 26/32 1st stage before). 1st 24/28, 2nd 26/32 36* motor 26* 1st, 16* 2nd 5.25# 1st 5.50# 2nd. 950# Bottle Pressure (pulling from 2 bottles). Conventional headed (Brodix BB4s) 540 BBC, single carb, 11.5:1 Compression, n20 camshaft. Crossed @ 7400 with almost zero driveshaft slippage (tight Hughes N20 Converter). Have NOT installed MSD 7530T Box, so this was on "old school" 7AL2 Box.

My mechanic saw a "puff" of smoke on the topend as I crossed, and so we looked at the Data Logger & all of the Plugs...the first 7 Plugs looked "good to rich"...not very much heat in the plugs (Autolite 3932), and the fuel top ring + in to the 2nd ring dark black. Crossing A/F was in the mid 10s on both sides of the block (dual O2s).

Well when I got to the LAST PLUG (#2), the strap was burnt off in the turn with about an 1/8" of the strap left. The rest of the Plug looked identical to the rest of the Plugs...rich. And Yes, I clicked the Igniton "off" when I crossed, and towed the car back to the pit area to read the plugs. We sure hope we did not damage a Piston, but we will do a leakdown in the AM on #2.

Another racing friend of mine that is also a mechanic, said he thought the problem was not a "tune-up" issue, i.e. Timing or Fuel, but rather very simply that I was using Plugs that were too HOT, and suggested a Colder heat range plug. The other 7 plugs sure don't indicate too Hot a Plug condition.

Should I add some Fuel Jet to just that #2 cylinder? Timing change?

I suspect SJ is in route from home from Orlando, but I will try to talk to him about this in the next week. SJ sure has us making killer POWER, and the Lil Sumptin '71 Camaro is rolling for sure.

Thoughts are appreciated!

whatever you do dont add fuel to that cylinder take nitrous away!!!!!!!!! trust me.......

[Scottyk]

I meant check the lash to see if you did indeed have a valve train issue, should be loose in that cylinder in something is stuck under the valve..

[jonesy1]

my educated guess is where there "smoke" there is fire!!!! sounds like you pinched a ring....

[fofo]

O.K. Will. I'll ask SJ about the Plug Heat Range. If nothing else, I can run the same Plugs but put a Heat Range colder in the #2 hole. Or just go with 3931, 1 step colder all around. Personally, I like the stouter strap of the Autolite vs. the NGKs (that I used to run), but then again that's an "opinion" call in that I'd prefer having more Heat remaining longer in the Strap than Heat in the strap for a shoter period of time resulting in burnt pistons.

Scott, the Valve Lash looked fine, and we could not see anything clear enough with the Boroscope we have, so we will take the Head off & see what's up. The compression is perfect in 1,3,5,7 and 4,6 and zero in 2 & down 50% in 8. So one thing is that it appears the Passenger Side was the side affected the most...for whatever reason. I still think it is from an overly Rich condition, lifting ring lands, or a bent valve, but no explanation yet for the #2 plug being so hot vs. the others, other than that #2 just runs hotter (and may need colder Plug). Seems I recall BBC #2 & #8 run hotter than others.

Jones, I understand, and if it proves to be a lifted ring land from too Rich a condition, it seems logical that we would REMOVE n20 vs. ADDING Fuel in #2...again, we'll see what SJ says, and my engine tuner.

Will, yes, we check the Timing Retards regularly whenever we change the tune-up. The 1st stage retard is activated by an "on" switch, and the 2nd stage retard is activated the same way (currently -10* when 1st stage is "on", & another -10* when 2nd stage is "on"...1st stage activated by release of TB & 2nd stage via a Digiset).

Thx again.

[fofo]

Well, we took the Passenger Side Head off tonight, and not good. #2 has a burnt Piston near the Ring Land, a hole large enough to result in zero compression. #8 has a lifted Ring Land, causing a 50% drop in compression. We did not take off the Driver Side Head, because the compression was good, but we will when we take the engine apart & cleanup the cylinders bores at the machine shop, etc.

So from the Data Logger & visual inspection (Plug Reading), this is what we suspect happened. The tune-up was too Rich on the 2nd stage, resulting in a lifted Ring Land that concluded with two burnt Pistons. The FP was @ 5.25# on 1st stage & 5.50# on 2nd stage. We had tested the tune-up on 330, 1/8, & 1/4 mile hits via the Data Logger & visual inspection of the Plugs, but when we ran both stages to the 1/4, it seems the overly Rich tune-up caused the problem to the #2 & #7 cylinders. This Rich condition was aggravated by the Bottle Pressure (verified via the Data Logger) dropping from Launch at 980# to crossing at 888#...richening the tune-up even more than 1/8 mile test hits (I use two 10# bottles!).

Now as to the #2 Plug strap damage vs. all 7 others showing no signs of Heat, we can only speculate. On two occassions over the last week, the n20 Noid on the Passenger Side (same side as #2 & # stuck "open" for an instant while purging through the Motor. While it did not Rev more than 5000 RPMs cause I caught it very fast, it may have damage the #2 Plug, which then further burned at the top of the "fatal" 1/4 pass.

We think our Timing was just about right, based on the Plug Reading (26* on 1st & 16* on 2nd stage), but based on the Data Logger A/F, our FP needs to be lower...closer to 5.00 on 1st stage & 4.75 - 5.00# on 2nd stage...especially on full 1/4 passes when the Bottle Pressure tends to drop toward the end of the pass, lowering the A/F toward 10.5 - 11:1 (too Rich).

I will order some new Diamond Pistons & Hellfire Rings & SCE Head & Intake Gaskets tomorrow, and have the machine shop check our Valves & Springs to be safe. We hope to be back racing again soon, and the Lil Sumptin will be no doubt faster than before when we get the tune-up right...7's here we come!

I hope others will learn a few tidbits from my experiences on these issues. If so, taking the time to share thoughts with other Racers will be time well spent.

[trap]

You need to go over to the nitrous forum on YB. There is a plug reading section and a section on lean vs rich. I'm a run it lean guy my self. When you take the strap of a plug it is because of timing and or way to much fuel. Willing to bet it took the area around the intake valve. Cylinders 2 6 8 an 7 on a bbc will need to have different tuneups in them. Most likely you hurt that piston on an early run it just gave up on the last run. Just my two cents

[jonesy1]

Originally Posted by trap

You need to go over to the nitrous forum on YB. There is a plug reading section and a section on lean vs rich. I'm a run it lean guy my self. When you take the strap of a plug it is because of timing and or way to much fuel. Willing to bet it took the area around the intake valve. Cylinders 2 6 8 an 7 on a bbc will need to have different tuneups in them. Most likely you hurt that piston on an early run it just gave up on the last run. Just my two cents

Whats up Trap???? I would agree possibly pinched it on the run prior and burnt it on the next one. I have been having some issues with the "even" side of my motor too!!! come to find out that I had a bad continuous duty relay on my second system. I found it only after hurting the motor twice both times on the "even" side. I knew that our tune up was ok so we went thru each system till we found this relay!!! Each time that I cycled the 2nd system on the 3rd try each time this realay would start humming however when the car was running you couldn't hear it, and it just so happenened that the motor burnt up the 3rd pass each day at the track. I will be checking those a whole lot wore than before. FoFo are you using theses relays too?????

[fofo]

Thx Trap, and will do in the future. I suspect you are 100% right, and after talking to SJ, I will make the necessary tune-up changes going forward.

Jones, as I mentioned, I'm not the mechanic or the technical guy...I just Drive & Pay the Bills, and know enough to be dangerous...hehehe. But, I think we have two of the larger Starter Relays for each of the the n20 stages, & I don't think your issues in that regard on Timing apply to our problems.

Thx again for your time, guys. The "good news" (if there is any after I spend $2,000 fixing this problem) is that all indications point to the fact that the car will run FASTER, because the tune-up was overly RICH...and that 7 second ET is just around the corner. My data indicated that I was on a pass of 7.95 @ 173, when the #2 dropped 7.83 seconds in to the pass.

[redcam622]

Originally Posted by fofo

Thx Toma. 540 Motor never dynoed but based on performance, we figure it is making 900 HP. Takes 1200 HP to run what I did on 1st stage (166) & 400 to run what I did on 2nd stage (171), @ 3400#. Our DA (about 100' this weekend) is really good over here in South Louisiana this time of year because we are right at Sea Level...also Lean condition for n20!

I agree that we are Rich based on the Plug Reading & Data Logger A/F...as you'd probably guess the A/F is all over the board on a 1/4 mi pass (example 13:1 down low when the TB was release @ 4000 & flashed to 5400, & 11:1 when shifted @ 7600, crossing 10.5:1). No big difference in the A/F 2,4,6,8 or 1,3,5,7 header bank.

Re: Timing. Motor is at 36*, 1st @ 26*, 2nd @ 16*, which seems like a lot out for a lage CC conventional Head & 11:1 compression & n20 Camshaft with 115 LSA. I hesitate taking more Timing out because NONE of the Plugs showed much Heat at all...not much change in color, etc. Might try another degree out of 2nd stage.

Is the 3931 Autolite 1 step COLDER than the 3932, and what about going to a NGK 9 or even 10...a lot of racers prefer the NGKs because they feel they are easier to read. The Autolite seems to have a "stouter" strap.

We will take a look at the leakdown compression today, and hopefully if it is not too bad, we can put a fresh set of Plugs in, and go about our business. This 540 will be replaced shortly with a 598 Big Duke aluminum Brodix block & Big Duke Inatke with 2 & maybe 3 SJ guns...should make 200 more HP, loads more Trq, and weigh 100# less, so I can get closer to class weight of 3200#.

Then I know I'll need to replace the 7Ll3 with the 7530T Box I have!

Thx again!

3933 is colder not 3931..ngk10 crosses to 3933,,,i've used both..NGKs are easier to read,but perform the same.