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Author Topic:   Well.......She make big boom boom.....
goinrcn44h
Member
posted September 06, 2004 04:00 AM
OK,
I guess I was close but no cigar kinda thing, saturday night at Skagit had "something" spin-let go-stretch-break, etc in the bottom end in my 360. My gut feeling tells me its likely a spun main bearing, felt too heavy to be a rod knock so I assume the next would be a main. I suppose it could be a broken crank, or broken rod possibly but I doubt a rod broke. no holes in the pan or leaks anywhere. I won't be able to find out what it is for a while yet as I leave my car in washington 550 miles away. and didnt have a plan on bringing 2 rigs home. so the truck and trailer stayed.
2 weeks ago I had gotten it hot (250-255) so I went up a day early and wanted to do a complete leak down, etc. I pulled the girdles and all that and found first about 7 rocker studs loose, nothing was bent or broken or in anyway hurt , etc, they had just came loose...I assume from the heat. I was pullin them anyway to back the rockers off to leak it down so I retorqued them at 55 stead of 45 and all torque'd good brodix 11x heads. did the leak, 6 holes at 4% orless w/ piston down and cold, 4 and 6 were about 8% down and cold so I knew nothing was damaged up top, head gaskets werent leakin, etc...
changed the oil and filter found same as always , nothin, the plug on the tank did have a slight lil bit of a graphite like film, but I attributed that to heat from the last race. so changed oil, checked everything , set the barrel valve, etc..fired it up for packin and all was good. maybe a touch fat, but otherwise real good. practice , real crisp smooth . qualified my personal best time of the year 12.61 which sucked overall, but was my best so that was ok. in the heat was in the line cause track was narrow yet and on last lap off 2 it just let go, no warning, the death rattle , like to knock your fillings out kind. I had a hard time gettin it out of gear, but did goin into 3, then just killed the mag. dropped the oil from the pan and found magnetic pieces on the plug( its magnetic) so either a bearing really came apart ( I have done that and this didnt look exactly the same, the pieces I seen weren't really blue/blackened from heat if I remember correct, which leads me to believe somethin broke ( crank I would guess, or rod ) hadn't over revved it or anything, turnin my normal 7900-8000 and still had pressure 60 or so , and 190 temp... once I get it back and pulled out it won't be tough to figure out but just throwin this out there. eagle rods, scat crank, srp pistons by schwanke, etc... dry sump, sprint motor, nothin spectacular but been stayin together till now. had about 20 shows on everything cept the main bearings which had 13 or so....
44H


2nd2none
Member
posted September 06, 2004 04:26 AM
Did Tim build this motor or did you just order the stuff from him?


awkwardjeff
Member
posted September 06, 2004 12:12 PM
I would think with the over heating you lost the torque on the head gaskets.....when you leaked the motor it's only 100psi....compression is much greater, and I suspect the compression pushed the gasket out. I suspect it pushed the gasket out in hot-laps, then when you were in the pits with the motor shut off it allowed water in the cylinder. Was the motor harder to get rolling over when you pushed it off than normal?? I suspect it bent a rod......this would cause the piston to scuff against the cylinder wall and the film you see in the oil is aluminum. Then bent rod finally failed, this could have caused the crank to brake also.......

Like you stated you will know when you pull it apart. Tim will give you good information also........ You can also bend a rod if you stall the motor while racing......with injection you fill the cylinder with fuel, then when you re-start you bend the rods...

I would suspect the overheating did the job this time........ anytime a motor goes over 230 degrees. the gaskets NEED to be changed if the compression is over 11.5 to 1 . some people will retorque after over heating, but personally i've had too many problems trying to save $100 on head gaskets.... I don't play poker, not when I gotta ante up a $8,000 short block to win a $100 set of gaskets..........

[This message has been edited by awkwardjeff (edited September 06, 2004).]

goinrcn44h
Member
posted September 06, 2004 12:47 PM
when I had the rockers off to retorque the studs and all, while it was open and there I went ahead and ran the the head studs. they were all as they should be. Also, there still is no water anywhere other than where it should be, and it did not hydro lock, that I know. A bent rod would have vibrated even if it was a little it still would have, and this had no vibrations or the like. I have a very good feel for engine problems, and in practice it was rippin. so I am led to believe if it was going at that time, it wasnt enough to be felt yet. and when it went it kinda went all at once. that is why I am leaning toward a breakage/failure from the **** happens file... When I leaked the engine, I did alot more than the average person would do I imagine. Also the day I got it hot, I had lost no water until I was finished with the race and actually stopped the engine, at that point the cap blew off. which if its gonna happen thats the way you want it. I had plugs out after practice and they were more or less perfect, good temp, pressures, everything was A ok, till it broke..lol..
This is good though, keep em comin, this kinda thing at some point can help everyone out, and what not to do, which is as important as what to do, ....
44H

[This message has been edited by True Blue (edited September 06, 2004).]

awkwardjeff
Member
posted September 07, 2004 07:57 PM
You ran the head studs and they were fine?? Okay help me out here.....heat expands metal, block expands more with over heating, heads expand more with over heating.....this crushes the gasket more than normal operating temp .......so, the head torque is not correct..... WITH THAT SAID..... You maybe correct in the fact of just a part failure that had NOTHING to due with the overheating problem.

If you can feel a bent rod you are some kind of driver.......

goinrcn44h
Member
posted September 07, 2004 08:04 PM
well I have never personally just bent a rod, so I wouldn't know for a fact, but I assume a bent rod would vibrate at the very minimum some, or atleast enough that you'd feel it. on a sprint engine we have no balancers or anything else for that matter. thats a huge issue in everything bein straight and blanced proper. a little is a ton at 8000+ with nothing out there absorbing any harmonics or anything, but you also feel everything just before it flies out the side usually as well. I didnt really feel any vibrations or anything that was causing major alarms.. I think I will have it back here sometime next week and then we'll know, but thanx , apreciate it.
44H michael harris


awkwardjeff
Member
posted September 08, 2004 10:11 PM
I have race almost everything, including sprint cars. I have built lots of motors, including sprint car motors. You may not have a balancer on the front, but you have a crank driven water pump that HELPS absorb the harmonics. I had a 406 that had a head gasket go out, my father changed head gaskets. I ran that motor 12 more nights, NO VIBRATION.....when I pulled it apart over the winter it had a bent rod in the cylinder that was leaking water......that was the ONLY part of the motor that was hurt.... re-used the piston. I had another motor that on the 61st night of racing picked up a vibration on the 3rd lap of a heat race, very noticable.... I told my father I thought the crank was broke.....we checked what we could and ran the motor...... raced it 2 more nights because it was the end of the season and I didn't want to bolt in a NEW motor for 2 ngihts then sit all winter. When I took that one apart it had 2 broken main caps. Crank was checked......NOT CRACKED or BENT. Re-used everything but the block.

I don't say this to brag, but to help you understand I have a good idea of which way the earth is spinning...........


I hope you post on here what you find when you do pull the motor apart.


goinrcn44h
Member
posted September 09, 2004 01:57 AM
I could be wrong, very wrong in fact, I have never bent just the rod. but I did forget to mention one thing in fact I forgot it actually happened till I was talkin w/ the guy that pitted for me that night. But when I was gettin changed I noticed on my left pant leg some alum shavings. And so I looked on the floor and was more in there. so obviously they came from the u-joint, torque ball area, well, unless I am wrong the only way somethin could hit in there is if something was moving a direction it shouldn't be .... all else being equal of course. if the crank broke it woulda walked the joint around some at min. Thats another reason I think that its the crank...
44H


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