When **** hits the fan

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MOPAROFFICIAL

Oogliboogli
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Or in this case... when you jet too lean.
It's not necessary, but I'm going to share my lesson with you all, save you some time and money this way.
I typically run 91 with a bottle of Lucas octane boost on the street and 100 sunoco at the the track....not this time. First run was ****, garbage reaction almost half a sec....left okay..but spun in 2nd and peddled for 8.0 in the high 80's.
Track is just over 2000ft, it was a hot dry day... I run one jet'75' under stock'76' @500 ft ... I dropped to '74' primary and took some slack put of the msd cap "they always have 2 degrees over movement" and went for another test run.... hooked hard on street tires 'track prep is decent there' but then got some hop at the top of 1st....its pulling harder, great, then hit 2nd....it pulls into 6200 or so and then it goes away, no power... let off the pedal and as I did I heard the old "rocks coming off the tires into the wheel well noise" and knew something was in pieces, turned it off and just coasted through the traps.... got out and looked for oil and **** sticking out of the pan, nothing.

Towed to the pits
Pulled the plugs and coolant shot out.
Proceeded to pull the carb, valve covers, all plugs.
It shattered a piston,pin and the H beam lumberjacked the cylinder through and coolant filled the crankcase and went in through that cylinders opening valves into the intake and "plane sharing" cylinders. 'Dual plane intake' so you can figure how.
It was no.5
Could have been the tune, easy, could have been past tuning that knocked off a ring land and it was a ticking time bomb.. I'm leaning more toward the tune that day.

This motor consists of the following
'78 360 block .040
KB hyper quench domes set @.030 quench
.004 skirt
Herbert street solid roller .575 251@.050 108 288dur
Morell rollers drop in style
Portered J heads 284/196cfm 2.02/1.60
K motion 800 220lbs@ 1.75 seat 495 open
Comp magnum arms
Ohio crankshaft nodular iron 4" crank
Ohio h beam rods w/arp 2000 cap screws
10.1 comp
8.9 dynamic =185 psi cranking
Mildly ported LD340 dual plane
Demon 780 dbl pump
TTI step headers
3" exhaust to bumper
245 60 14 bfg
3.73 gear
4spd
3200lb or so car weight

As a friend would always tell me... "always remember.. if you're not breaking ****,you're not learning"

I had a great time, I was even excited to find out what went.
I'll post more pics as I get it all out of the car, but I can already see it all, windowed that cyl.
In the end, the crank held up, the rod never left it as a matter of fact, the lifters are cherry, the cam will need touched if not a regrind, no bent valves.... It is what it is....and that is I already have another block in the machine shop as I type this... I love this ****.

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Best thing you can do when the motor get loud or make funny noises... is to shut it off.
If I hadn't... I'd have lost more money.
There was even a piston chunk jamming the intermediate gear... like God lending a hand.


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I thought it was always the machinist fault !!!
I have broken more than my share of motors,always pushing for extra....
Oh well, bet that motor gave lots of miles and smiles...it will live on in another block.
Some people just blame orhers...
Glad it on the mend already.
 
Looks to me like the engine just told you it was time for a freshen up. running lean had a little hand in it that run?
 
I think your engine has an infection it's pissing green! :rofl:

So sorry for your loss!
 
I thought it was always the machinist fault !!!
I have broken more than my share of motors,always pushing for extra....
Oh well, bet that motor gave lots of miles and smiles...it will live on in another block.
Some people just blame orhers...
Glad it on the mend already.

Very true, though it happens sometimes to be true... mostly its user error...though I've had bad valve jobs "chattered " that didnt seal. The original shop I worked at 10 yrs ago did the original valve job, guides. I only ported, milled, cut stem height, mock and set spring pressures. Long story short I later had another shop do the valve job after a bad leakdown pointed to the exh valves o.o.r.



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That is a very thorough job of destruction; no half-measures here LOL!

The dry day was probably a factor too IMHO. Dry and/or cool conditions can get a setup to detonate that was fine all summer long with high temps and humidity. Some testing done in the 80's showed that a cool, dry day's air density and lack of moderating humidity is roughly the equivalent of losing 3-4 point of octane versus a humid, warm summer day. I had an acquaintance lose a turbo rally engine that way; tuned it to the max in the middle of summer and ran like dynamite at a rally at high altitude on a hot, humid summer event. Next event was 2000' lower and on a crisp, cool fall day, and 'blam-o'... thar she blows.
 
That was a whole lot of motor for those little tires! Did it actually hook? What clutch do you run?
Center force dual friction, they prep very well there... but mid track has had a oiling 4 cars before me. They do their best to clean it up.
Hooked better than any other track I've been to.
 
Wow! Looks like a grenade went off in there!!!
And that’s why people bad mouth the HyperU slug.
But MPO was upfront about it. Admitting user error with pictures as your fair warning in the state of tune during racing conditions that change.

In the past, people would just trash the pistons make up calling them ticking glass time bombs and junk. I haven’t had any problems with mine in years. Though I don’t push them like MPO does in racing often.

I stand up and applaud this show and tell.

Speedy recovery to you!
 
In the past, people would just trash the pistons make up calling them ticking glass time bombs and junk. I haven’t had any problems with mine in years. Though I don’t push them like MPO does in racing often.
FWIW, I have used stock replacement hypers in my 2.6L Mitsu Starion rally engine, turbo'd to 14-15 psi, and putting out around 1.75 HP per cubic inch. Nary an issue, running a few thousand miles of hard rally stages on them, and spending lots of time at full boost, in all sorts of weather conditions.

The ECU would tell you when it detonated via the stock knock sensor, so it was not hard to avoid detonation in setting things up.
 
Can't see why not. One cylinder leaner than others or hotter, etc. I detonated a forged piston into partial destruction once, and the others were fine.
 
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