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Discussion Starter · #1 · (Edited)
As many of you know, I bought Buffmans Roadmaster, and the motor went out less than a month later.

Background on the car.


RAISS Intake
F-body MAF
52mm TB( ported stocker)
Bob Noble PC'ed intake manifold
Stock cam & Stock heads
CMS valve springs
1.6 Pro Magnum RR's
CIA Tri-y's, no cats & cut outs
Pypes X pipe, Spintech Prostreets

3000 Edge converter
Team Tripp Tranny
3.73's, eaton, etc

Tune is based off a Herter 93 Octane tune. The A/F ratio had been extensively fine tuned by Buffman, with a wide band O2 sensor from Tom Fish(Spartus). I remember him saying it was on the safe side of stotch. I don't remember the number, I will ask him. I'm dyslexic, and bad with numbers. He always ran Shell 93, which is what I had been running in it as well.

I took it to the drag strip, and filled it up at shell when I got home. The car didn't run as well at the track, as I thought it would have. It ran 14.05, when it's best had been 13.52. I don't remember the weather, or what it was corrected. I will have to double check that. As I left the station I thought my rear window was fogging up a bit. I thought that was odd. I left the next light briskly, and thought I noticed a little smoke behind the car. Over the next few weeks, the smoking got worse, and worse, until it started to miss fire. That was when I saw oil leaking out of the #7 exhaust gasket, and one of the bolts at that port MIA. I checked that plug, and it was caked with oil deposits. Put a new plug in, and drove it for a few more days, since it was the only legal car I had right then. I barrowed a compression tester, and came up with 20psi on that cylinder, and another fouled out Autolite 104.


So the swap began. I pulled the motor out a few months ago, but I broke my hand a day or so after I got it out. Last week I finally had my cast off, and decent strength in my hand, so I pulled the head off. I found that the #7 piston is cracked, a chunk missing, the top ring it busted, and went through the chamber.

Any thoughts as to what happened?
 

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Discussion Starter · #3 ·
Buffman Engine Damage. (I realize it's not much. I will show some more entertaining pictures of Jesus's Engine, in the next post. :D)

 

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Discussion Starter · #4 · (Edited)
And here is the motor That went in Jesus. I part of what happened here. I'm fairly certain I spun a rod, and I tried to drive it to the County Police Motor Pohl, to have them listen to it. Didn't make it. :D These are just for entertainment. There really isn't anything to figure out with this one.

 

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I might have no idea what I'm talking about, but...

I would say maybe your ring was shot and since you kept driving it, the extra heat and lack of lubrication caused the cracked piston, etc.

Again, I'm not a mechanic, that's just my first guess.
 

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Stoich fuel ratio is 14.7:1. This is what the car should run at low throttle cruising. This is really difficult (and not necessary with regular gasonline) to change in the tune because O2 sensors keep adjusting it.

At WOT fuel ratio should be much lower than that, somewhere in the mid-12s to low-13 range. Are you implying that the wideband O2 sensor measured 14.3:1 fuel ratio at WOT? That could definitely kill the engine.
 

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Cory and his weird way of explaining things.

According to the wideband I borrowed, the Tune I received from PCMforless had WOT AFR aroudn 13.6 to 13.7....

I fine tuned the thing down to 12.8-13.00 (on the street, which is what I was told was ideal street tuning).

The engine always ran like a top, and probably not too long before I sold the car, I did a compression test on it (was going to put nitrous on it), and everything was within 5% of each other and in teh 200-215 range IIRC.

I always ran 0w30 German Castrol for 3,000 miles.

The only time I ever saw oil burning out of the exhaust was at 6000rpms when the engine oil temps weren't quite 200*.

It did have an incident I believe from the intake or something (powdercoated) that it had a high injestion of silicon from the UOA, but subsequent UOAs showed normal levels of wear metals, and even the one with the high silicon, didn't show aluminum or anything way above average.
 

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Discussion Starter · #9 ·
Yea, I'm something awful with numbers like that. I flip flop numbers around, and can't keep them straight. I thought stoch was 12.7, but it didn't make sense that it would be on the lean side of stotch. cwm3

:D
 

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looks like detonation to me.
when you raced it,did it have enough fuel in the tank to keep fuel pressure at the injectors? lean it out enough,and it will start to find its own fuel.
 

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Discussion Starter · #11 ·
It had a Full tank before I left for the dragstrip, which is how I normally take my cars. Drove 80 miles to the drag strip, ran about 10 runs, then drove home 80 miles and filled up again. It wasn't low enough to be concerned, when I filled it back up. But I don't remember how much it took. I try to have at least a half tank before I take it down the track. I know the baffles in the stock tank are garbage.

If it only got 15mpg on the way there, it would have had around 18 gallons when I started. I'm sure it got more, since it's almost 100% highway from the shell station to the dragstrip. I drove maybe 2 miles on non-highway roads.
 

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That there looks like it is detonation. That piston was cracked for a while, hence the smoke and oil in the exhaust. Forget blow-by, you had splash-by.. . #7 is a classic one for running leaner than the rest. I think it melted away the crown until you had no support on the ring and then that fractured. All the spotting on the face of the piston looks like detonation, but it's hard to tell from the pic if it's just witness marks of the bits of ring bouncing around the chamber. Does the crown look more kinda like English muffin, or it the irregularity have little surface to it, mostly discoloration?

Note that the hole is closer to the intake side.

What does the bore look like?
 

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Detonation....now put it back together.
 

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Discussion Starter · #15 ·
What does the bore look like?
The bore looks fantastic. I could not find damage anywhere. I will have to take a closer lok for the rest, but most of it looks like ring damage.

What does the cylinder head and valves look like?
This is all I took that night.



Detonation....now put it back together.
:D Oh, the car will put back together, only better. This engine is going under the bench for now. The engine going back in, is the 845 cammed one pulled from my 96 9C1. I wish It had more cam, but for now, it works. I'm very poor right now. Buying the Roadmaster cleaned me out.

 

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Go stroker fool! You'll never go back.
 

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Discussion Starter · #17 ·
Oh... I REALLY want to. But first, I think it would make more sense to have a set of heads that could really unleash a 383. I don't have enough money to buy gaskets and paint for this engine, let alone a stroker or a set of AI heads. I'm working on turning things around. :D
 

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could have had a weak injector on that cylinder having it run leaner than the others
 
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