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Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by gt_diesel, Aug 10, 2009.
Almost 4 Threads
Wrong pics.... sorry
Thanks GT. so do you think your plug #8 has heat in the threads like the picture I sent you. It maybe just hard to see in your picture. All the other pictures I sent you that you posted are beyond the cadium left stage. I think we all know what rich with cadium still there looks like. The plugs were getteing a little old so the frost wasn't fresh. It actually will look like powdered sugar sprinkled on the plug when it is first taken out.
I think mine looks like the first picture, only not frosty on the top... Dont know if that makes much sense?
Then with no frost on the top maybe the threads at the end of the plug are exposed more either because the head has been repaired or the plug sits deeper in the hole so the threads are stick out a little. Next time you have the head off then put a plug in it and look at how it sits in the chamber. See if any threads are exposed. Until that time for safety I would increase the jet by three or four sizes.
I am sure the plug goes into the combustion chamber... The heads are new, but take a look at the pattern of the burn
here are two pics of the same plug... Looks ok on the top, but you see the cadmium burn off down part of the threads...
Side with markings to see what I mean.
Most all the plugs are the same.. Even the # 8, only half the plug is burned down to the 2nd thread.
Hers my nickels worth, I would lean out ( 34s )the cyl that are rich and leave the ones that are lean alone. that way you will get your top and bottom closer to 60/40 then richen up the main jet. Might even put 50s in the hat, got to keep that blower cool. leak the barral valve to 85%, you got to know that the blower is a big air pump, opps, a big HOT air pump. Gene Terenzio Sr.
Mike, did your heads have steel inserts in the holes of plugs pictured?
No they didn't.
I wonder if we are talking apples and oranges aka Hemi vs conventional chevy
Last friday I leaned out one motor, torched the head, blew the head gasket and o-ring wire out like schrapnel and my plugs still weren't as lean as what Mike's pic are showing.
Somethings different between Mike's stuff and mine,,, maybe hemi vs conventional chevy???
I have a pile of valves, pistons and rewelded heads that show my BBC's can't run that lean.
That is a good point....
How much heat in your threads on that cylinder? Do you watch the squared off ends of the ground straps for nipping or rounding? Did you show any. Maybe too much ignition advance. Could you see where the blue line was in the groundstrap? I am sure that all motors have the same AFRs but the big thing is timing. Can you see any detonation in your upper rod bearings?
I should start by saying that motor has been running a consistent 1/2 burn on the plugs until thursday night when it leaned to about a full round, than fri. way too lean. (I adjust for the DA). I didn't know why it leaned itself on thurs but hindsight I shouldv'e checked for plugged hat nozzles. The reason it leaned out so far is that I had 4 hat nozzles plug.(Mike remember the JIC screen/filters chat from a few weeks ago, back then I put them in my port line, than on saturday(the day after the torched parts) I also put one in the hat line)
So to answer Mikes ?'s, as I recall. Threads on that cylinder? 2
There was little to no round on the gd straps.
Too much ignition advance? Not a chance. I've seen how too much advance kills HP and parts. This motors ignition was tuned in on the dyno and I won thurs and got 2nd on sat.
The Blue line, I can't recall. I'm not acustom to this method. I tune the advance setting according to HP #'s on dyno.
I have not looked at the brg.
Within the last year I have;
-torched the head (warped valves) where I didn't even melt the gd strap and the piston was fine
-melted the gd strap off where I didn't hurt the head(besides warping valves) or piston
-did not melt the gd strap off, torched the head and scorred the piston
I don't understand why or how it can vary so much. Is it because of the cause of the leandown??? The first one listed was because of the hat nozzles plugging. The second one was a port nozzle plugged (it was also a winning run). The third one listed actually happened twice in a row and ended up being a bad port hose.
I wonder if the duration of the lean has something to do with which parts it hurts??? If a "flap" in a hose is opening/closing/opening/closing I would think it would be different than when a nozzle just slams shut and PLUGS. Than does it happen at the beginning of the 12 second run or the end. In the first instance I know when it went bang but don't know when they plugged.
Sorry to ramble, I hope it made some sense.
Anyone have some thoughts?
PS By listening to ITA people and my competitiors, it appears that the hemi's use more fuel to make the same amount of HP. My BSFC #'s are about 1.2. Should also remind everyone that I tractorpull not dragrace. (maybe thats a difference also) But yet a 3.5 second inertia dyno run and a 12 second on track run are within .005 in the MP.
One of the big differences in a tractor pull run versus a 1/4 run maybe the longer time in running up the RPM range. Do you use a transmission and shift gears or just stay in one gear? In other words we run up the rpm range in each gear fairly fast so we don't stay at the peak rpm and boost point very long. If we did then I would think we would have to run our motors a lot richer. I sent you a PM to ask for some info. I would be very interested in pursuing the difference. If interested then you can also email me directly at email@example.com
Another big difference is most of the Blown Alky pullers I've seen run a little less timing, A LOT less blower OD and max 'em out at 8500-8750RPM's. Their motors last a long time between regular maintenance unlike a Top Alcohol configuration because they're not running on kill, of course you're looking at asking almost 1,000 less horsepower out of the "same" motor. Most also run glide style clutches instead of the pedal style we're so used to.
Typical run for us is 8500 RPM for about 2 seconds than it drops to 7500 over the next 10 seconds. These are in the ballpark. Track conditions can change this.
We select the gear before we take off and thats the gear it stays in. In our vehicle their is about 4800 HP going through the manual tranny, no shifting. Each motor has a 3 disc crowerglide that doesn't slip much after about 3500 RPM.
Your saying you would have to run richer if you ran like us, but I'm saying you already run way richer.
Our main pill on the quick dyno run (correcting for DA and having the same plug reading) vs the long track run is within .005".
Ignition timing, I don't know, mine is set for the highest HP reading on the dyno.
My rev limiters are set on 8700 and I've made numerous runs this year where I have heard them just barely touching'm(they are soft touch).
I used to run 68% over drive until the rules slowed us to 50% and than slowed us to 43%. (I'm thinking some year they'll make us run them backawards) So 8000 RPM x 1.43 = 11,440 rotor speed
We make about 1600 HP out of an 8-71 limited to 43% over and conventional style BBC heads.
SoDak,,,,Your PM is too full for me send you a reply to your PM.
What the main pill is doesn't tell me if you are richer or leaner. Need GPM and boost at 8000 RPM and the DA so one can really compare plus the engine size.
So your run is twelve seconds long and in a single gear That is what I am talking about being the different. In a "normal" blown alcohol run we are at a peak in each gear for just a short period of time. We go through three gears in less than six seconds. Our motors can briefly tolerate short duration leaness (or mistakes) and can take that type of tuneup most of the time. The longest slow rise to leanest is in third gear and that is where we adjust the plugs for. Your head and manfold temps must get a lot hotter than ours so you now have a hotter incoming air charge coming into a hotter motor. It would seem to me that you have to run rich just to keep all cooled down.
The way I figured out how lean I can run is this: I slowly leaned while trying to keep things consistent and watch everything that I thought was pertinant. Than when I started hurting parts because of lean (warped valves, scorred pistons) I knew where I was on plug readings so I richened a little and I would not go leaner.
I have 1 cylinder that has a spark plug heli-coil in it and I forgot that it did. The insert makes the plug read richer than it is and my valve lash got tighter, so I than remembered about my insert, at which point I richened the nozzle.
I have a hard time beleiving that a plug reading would be the same in a billet hemi head vs a water jacketed BBC head, especially if an insert can change it.