Ok the first thing you guys need to realize, I'm trying to play on a cop's salary, so bear with me. This is going to be kinda long and drawn out.
As you can see in my avitar, I mud race. Two years ago I built the motor in this truck, and I think I screwed up in several ways, but I want to know what my worst mistake was, so I don't do it again.
Now to race in my class, I have to run factory head castings I.E. OEM only. No Stage V's even though they are cast iron etc. So I had Dan Dvorak build me a set of 906's with the large valves 2.14 in 1.81 ex. He performed his "super port flow" and his black magic whatever else he does. I.E cost me $1400.
I then had a 72 440 block machined. (Magnufluxed, Sonic Checked, Decked, Line Bored, Squared, Bored, matched to pistons ect.) The pistons were the Speed-Pro forged #TRW-L2295F30, I had them on the 6 pack rods, with a factory steel crank.
I first ran a Comp Cams 292 (.244 dur @.050, w/.501 lift). This POS didn't even make it through cam break-in. I then ran a Comp 280 (.230 dur @.050 w/.480 lift) I was able to run about a year on it before it rounded. I then switched to a Lunati 292 (.236 dur@.050, w/.050 lift). It was holding up perfectly, till the motor quit.
Other specs include a Edelbrock TorkerII intake, a Predator Carb, and MSD 6a ignition.
Now the first year I ran it, it sounded atrocious, at low rpms but it did wonderful if you could ever get it over 5500. The final race of the year, the truck freakin screamed, I out ran trucks in the class above me (and they are allowed gutting bodies, paddle tires, and nitrous). During the run I tacked out the motor (Tachometer goes to 8,000, and it was bouncing off the peg, furthermore the truck was in the air more than it was in the mud) but after the run was done the motor was running terrible, and that was when the major problems started.
After that it made this horrible noise, which I could only compare to detonation, however there were no signs of detonation. The motor would fire up and run perfectly when it was cold, but when it came up to operating temperature, it would act like it was fighting itself just to run. If you would put it under anykind of load, it would be the most gutless thing you've ever seen. And trying to start it at operating temp, sheesh forget that, you'd have to wait for about an hour.
The next spring I tore into the motor, and found second Comp Cam had rounded. I then switched to a Lunati. I also discovered that I had the cam timing off by a tooth (retarted) so I fixed those problems. And fired it up again, did cam breakin again, checked everything and it was holding up great. This time it sounded wonderful at all rpm ranges. However the seizing problem was still persistent. Nothing I could do would help this. Also the detonation noise was still there. It was worse when the motor was cold, and went mostly away when it was warm. Well the next bog I raced at looked promising, the truck was running perfectly (when cold, but whatever right?) Well the motor got warm while staging and then died, and I couldn't get it started again so I had to forfeit the first run. The second run I made it to the line. Got the green light, and the truck freakin launched hard, and the rpm's came up to about 5,000, and I went to shift to 2nd, and the truck started loosing rpms. I saw the oil pressure dropping, and it stalled.
The damn thing wouldn't crank over, and acted like it was completely seized. We pulled it to our pit, and worked for hours that night trying to get it to start or spin over even. We had a 1/2 in breaker bar on the Harmonic Balancer, and it wouldn't budge. After about 4 hours, it cooled off, and fired right up again. Well when I got it to my shop again, I pulled the plugs, which showed no signs of detonation. 6 of the plugs looked perfectly they were #'s 1,2,3,4,5,&7. #'6 & 8, looked like they hadn't fired in a while. I ran a compression check, and every cylinder was between 165 and 170 lbs. I pulled the valve cover, and everything was fine on the valvetrain. There also wasn't any problems in the ignition, that I could find.
Everybody was telling me how bad the Bosch Platinum plugs were, so I thought they were the problem, so I switched to the Copper Autolites. This didn't make any improvement. I went out still trying to tune, i put mufflers on it, so I could hear the motor. I hammered down, just like a mud run would be. The rpms came up to about 4500, the oil pressure dropped again, and it just died. I almost got it to start back up, but it wouldn't. I let it cool off, and this time this sucker is seized.
So here are the theories that I have been given by the other mud racers.
1: My rotating assembly was too heavy (I.E. Speed-Pro pistons + 6 pack rods = bad combo for racing applications) , and I over-revved it and screwed up the bearings.
2: I was running crappy oil, with too loose tolerances. (Rotella 15W-40W Diesel Oil)
3: I'm running Mopar
4: I was using the stock 3/8" oil pickup, and I starved it for oil.
5: The machine shop missed a bent connecting rod.
6: The flat camshafts ate the bearings.
7: All of the above.
If you guys can think of anything else that I did wrong, or anything else it could have been, tell me. I want to chalk this one up to a learning experience, even though it makes me sick thinking about it.