Some may already know, but a few weeks ago #5 rod of my 464 made its mind that it wanted to take early retirement after just 68 passes. I had just removed and cut the oil filter apart just before this outing and saw absolutely nothing in the filter to show any signs of issues. Took my 14y/o nephew with me, the air was pretty crappy, I figured it would only mustard about a 10.75 pass, which it ran dead on with a 4. Well next pass it made it about 500ft for it had its issue........but motor was still running when I clicked it off. This isn't a fancy build, but did have good parts where it counted. Finishline did the build, Wiseco flat top pistons, Molnar drop in rods, billet main caps, pistons griddled oil pan, arp fasterns throughout, scavenger oil system setup,, cnc ported TE2 heads, custom scotty cam, sp2, 1050 carb. Compression was 12:1, ran a best 660 time of 6.52@104. Was shifting 6500 and and 10 or 12 1/4 mile passes it would go through the top end 6700-6800. It appears everything from the cam up has survived, and will only need a combustion chamber blending on #5 where the piston just skimmed it and 1 exhaust valve. Head has a tattoo or the piston part number pressed in it niw...lol With the crude/lower dollar tools I have to check things out rod clearances on the other 3 journals are 0025, mains are .0030. And as you will see from the pictures below that the mains and rods minus the 2 on 5/6 journal look basiclly new. #1 shows signs or eating some of the trash that was passing through, but it has barely worn the dark coating away. The bearing could be honestly be reused. I'm not an expert but it appears that this might had suffered an instant part failure. I'll be sending the broken parts to Molnar for a professional exame, thanks Kenny Betts for setting that in motion. The mess if black on the top of #4 is from oil dripping on the exhaust valve.......the seals have been replaced but clearly it still is dripping.......need to verify its not coming from someplace else like around the guide or someplace else.......but the header tube inside looks very similar
Rod bearing pictures show all bearing but #5, it was pounded to nothing. The rod cap on #5 was broken into 3 pieces and both bolts broken. I bolt show evidence of heat, the other not really. I'm thinking a bolt failed and let the clearances go wacky and the rest is history. 6 of the rods should be reusable, and 6 pistons may also be but further inspection is needed to verify that
I would be extremely surprised if they admit a part failure. I had an Eagle forged crank break cleanly at the snout in a 347 I built for my mustang and Eagle claimed I had my blower belt tension to tight……problem was I didn’t have a blower lol. They said send it back (on my dime), and we’ll have a look at it. Never bought from them again. $800 lesson learned.
I've been running 100ll avgas gas for the last almost 20 years.......ran it with compression 11.5:1 with my iron heads on my last 464 which was a stk rod motor. That motor had 2500 passes b4 it got a pinhole in the sleeve and started drinking water. Timing setup is msd crank trigger and locked out distributor through msd 6520 box set at a 35*
Judging by the deposits left by the horrible flame travel going on there, that motor was in distress long before that rod let go. Those pistons should be black all the way across the top.. Your looking at what a piston that is undergoing detonation looks like. In mild cases of detonation, will see more complete coverage, and then just a ring around the outside of the piston top, where the piston is rocking in the bore when it detonates, and loses ring seal.. the oil getting past the rings cleans the carbon off the piston.. Your pistons have the next level of destruction going on there, the sparkly stuff on that close up pick of the valves in number 5 is aluminum from the piston tops, literally melted off the top of the piston. The piston top on number 5 should have kinda a rough finish on it, in spots. So your running what appears to be a 13-1 464, with 35* of timing, on 100 octane unleaded fuel? Honestly, I am surprised it lasted that long. 13-1 with Alum heads, even with a big race cam, requires at least 110 octane. I generally feel safer with VP C-12 in a motor like that, but I have run them on Turbo blue.. There are a number of reasons that it might detonate worse on one cylinder, usually that cylinder is leaner than the others, due to carb inconsistencies or manifold distribution issues. When you have an engine on the edge of detonation, and adverse conditions push it over the edge.. in this case, the hot nasty weather was not your friend, you get the engine destroying detonation that you see here. The pictures support the following hypothesis.. Motor experience detonation, more severe on number 5, but all cylinders have long term indicators of the poor flame travel and ring seal issues common with motors going thru detonation on a regular basis. Number 5 rod bearing failed, due to the detonation pressure pushing the rod bearing thru the hydrodynamic wedge of oil, and the bearing contacting the crankshaft. This causes rapid bearing wear, and once the bottom half of the bearing degrades, the actual stack height of the piston/rod/stroke exceeds the deck height plus the deck clearance.. piston to head contact occurs. The number 5 piston collided with the head/exhaust valve, side loading the piston..this process breaks the cylinder wall, which in turn causes the rod to bend, and then all hell breaks loose. Rod bending is a bit of the chicken/egg deal, could have been the contact bent the rod, and then bent rod broke the cylinder.. If the pistons tops looked as they should, (completely black across the top) and the rod bearing was good, then we could say that number 5 broke a cylinder wall, or the rod failed, but that is not the case here. It takes time to do that damage to the rod bearing and journal, you would not see this with a sudden failure, like happens when a rod does break in an otherwise healthy engine. Avgas cost you this shortblock.. Your beyond anything but expensive race fuel on an engine like this. or E-85, but that has it's own high maintenance issues. JW
uhgg, the cost of having hot rods! but hey, we could be blowing our money on alot worse things. rebuild move on and start having fun again! now on to more serious things i see wrong. in one of your pics. i do not know what you are trying to pull here but the "font" on the letters and numbers on the cylinder head {com chamber} dont look right to me? you sum kinda of stamper???? charlie,,,
The pistons were blacker when I pulled it apart there was oil and water in all the cylinders.....and alot of the black stuff wiped away with the rag. I'm not saying it wasn't under detonation, this is why I posted pics to get info from those that know more. When I do the math on compression numbers.....if I do it right I get 12.3. So yes I rounded a tick. If I recall the piston had something close to 9cc valve pockets we were .010 in the whole and. 041 gaskets w 4.385 hole My pistons from my other 464 all came out perfectly clean with avgas. 0 black on them period. Its totally possible the gas was the issue. I had been wanting to swap to a racegas to try, just never got to it, E85 is only a few octane points higher than avgas, but maybe its just enough
Jim, you make excellent points for detonation as the explanation. One minor poke, I believe hypothesis was the word you were after
Ok I was confused....I did walk out to the shop, took just a dry white rag from box o rag and wiped the piston all the black basically wiped off this is piston #5. The surface feel very very smooth to me. I tried to get a few pics not sure it show...but you can see after wiping where the exhaust valve kissed the piston
#3. B4 wiping and after.....oddly there is a slightly raised spot on this piston.....it shows up in the 1st pic b4 wiping. Its about .004 tall. Maybe what Jim was referring to starting
It's hard to tell for sure in pictures, what your looking for is tiny little dimples in the surface of the piston top. In the pics, it appears I can see areas like that in both number 5 and 7 pistons. IF our heads are 63 cc. then yes. your correct with the 12.3 number on compression.. I am so used to building the stroker stuff these days, anything flatop with zero deck, like I build every thing is up around 13-1. Regardless, 12.3 with 35* locked timing is not something I would reccomend, in this application, for 100 octane fuel. Pump E-85 is 106 octane, if you source straight ethonol is 113.. mixing with something like sunoco maximal, you can achieve about 115 octane E-85. But due to the reduction in charge temp that comes with the ethonol fuel, I would bet that motor would have been fine with the pump stuff... Ya, spell checker got me on that one..
Also.. with 68 passes, the fact you can wipe the pistons clean like that, is another indicator of poor combustion/oil contamination in the cylinders. The carbon buildup should be pretty solid by now.. Yes, if it soaked for a while in antifreeze and oil, that could be a factor here. But your bearing failure is the key here.. no way a bolt breaks and the rod hangs on long enough to do that kind of damage to the bearing.. JW
It's been sitting about 3 weeks since it broke......between being to busy and to discussed at it to start this process all over again...... It very well could be detonation, but isn't it odd that only bearing would had showed any damage from this.......I'm sure #6 got ate up from the heat and stuff from #5, but wouldn't some of the other 6 remaining also be starting to show the same wearing........if the burning was damn shitting in all 8 cylinders, if the octane was so piss poor, or the timing was too damn high, or any of the combination of the 3 to cause it, wouldn't they all be starting to show bearing issues?? I do believe the tune up was rich, the plugs did show that, plus it did pick up quite a bit when the weather cooled....like almost 2 tenths. Guess next motor ill spring for better gas and turn the timing back a few degrees. I started where we was with the iron head motor, I figured the tune was good there and there wasn't alot of difference....I knew i went up half a point....but though that would change tons especially when going to aluminum heads from iron On a side not I did redo my compression numbers, I first figured it with 4.0 stroke. Duh. Not a bbc. When I run it at 3.9 I come out right on 12, I used 65 cc for the heads, ill clean them and actually cc them. But I thought I was told that was what the come out after the cnc process
Jim, Thanks for taking your time to look at my issue and give me some insight, I know looking a pictures can be tough to get a true picture and I agree the pics show what look like pits especially if you zoom in but in life I don't see or feel them.....im wondering if its my lighting. Now I will say the way that carbon wiped off is exactly how its always wiped off in every motor we have run avgas.....even the 9.5:1 sbc a friend of the family raced. We pulled his split port aluminum heads off and went to a traditional exhaust port pattern head made by afr so he could get a better fitting header to get exhaust on the car for street driving So I wonder if that is something that is a byproduct of that fuel. Be nice to talk to a mechanic of planes and see if they see the same results.
Could be on the avgas.. it might not leave as much deposit..don't know, I don't work on aircraft.. Now, one thing that does not support my theory is the lack of piston damage.. but that could just be because it did not take much to push thru the oil wedge on the crank, and kill the bearing. Although if it's not detonating, where did the aluminum spots on the valves in number 5 cylinder come from?. That's molten aluminum, fused to the valve.. It is possible that you still had some other issue, but Avgas is way out of the range of fuel you could use in that engine. Min octane for that motor would be 105, 110 for some type of safety factor. That alone, regardless of what the parts look like indicate you had detonation. One thing is for sure.. I have never seen an actual rod failure, in the beam of the rod, or the cap, that has the bearings burned up and that happened after the rod broke a bolt or something. Let alone has killed both bearings on that journal. You lost number 5, and the heat took out number 6.. that takes a while. I have certainly seen what you have there, but the bearing was the first to go, it does not generally work the other way. There is so much force in two directions there, once that cap gets loose, it does not take but a few cycles of the engine before it begins to self disassemble. Not enough time to do that kind of damage to the bearings. Typically rod failures with a healthy rod bearing, results in great looking bearings with a bunch of gouges and dents in them. Look carefully at the main bores.. see how much clearance there is at the parting line.. it might have had .003 verticle, but bearings are not round, they are elipical.. measure what you have up toward the parting line.. If it's .005 plus.. that's not good. Oil Hemorrhage off the mains, which causes insufficient centralized oil pressure at the rod bearings, is the number two cause of rod bearing failure in a BBB.. and you will never see that on an oil pressure gauge. Number one is Detonation.. In fact, you could listen to most stories of engine failures, and guess detonation to be the problem, and be right about 80% of the time. Focus on the rod bearing failure. That was the Chicken, in this "Chicken or egg" question. JW
