Nevermind I just read up on it and wouldn't it have to do with how much lift the cam has plus type of piston, hence the valve reliefs that are cut into even factory pistons?
yeah basically interference means: broken timing chain/gear/cam bolt or pin + momentum of cam and crank = boom as for non interference means: broken timing chain/gear/cam bolt or pin + momentum of cam and crank = oops
LOL, yeah that's interference allright but this is what they are talking about http://en.wikipedia.org/wiki/Interference_engine
Simply put... non-interference means in the event of a timing chain/belt failure the pistons will continue to reciprocate without hitting/bending valves or causing any damage.
No, it fired right off banging, I killed it as fast as possible...obviously not quick enough, I talked with tech support at summit and he ask if the motor sneezed at first, said since I may have had the timing advanced it could have caused the motor to try to rotate backwards which could have broke the pin and caused the camshaft to go out of phase however he didn't think it could break a piston rod, also told me that not only would a loose cam bolt allow that but one that had been over tightened would cause it to loose it's structural integrity and com loose........bottom line he didn't know
I'm still going with not having the timing bolt torqued correctly......only issue is the broke piston rod, in everyones opinion they don't seem to think it should have broken a rod
Yeah, they are. That's why we have to check piston-to-valve clearance when we change cams. Roller 351W's blocks are much stronger than a 302 block and only slightly weaker than an early 351 block. Of course some people can break a bowling ball in a sandbox with a rubber mallet...
It's not a "totally always" deal...but when my cam gear sheared the pin, it retarded and the exhaust valves were all bent/broken. I was talking to a pretty well known Ford engine builder (mosty big blocks though) and he said most of the times he's seen a pin fail, the natural direction of the engine causes the exhaust valves to hit first because it is heading in the direction that is tantamount to over-retarding the timing. Like I said...not a dead lock so to speak...but definitely the most common. I talked to him because I had never enjoyed the experience before that little adventure lol. Oh yeah...one of my valve heads was bent in a "C" shape, and rolled out of the header onto the track! Did quite the number on my AFR heads...which I had tig welded up and re-machined. That was the last time I had a factory block in the car...we discovered 2 cracked main webs during tear down/inspection, and I switched to a Man O War block.
From what I'm seeing here.. that rod was already twisted to begin with and then finally decided to let go after the motor fired up for that last time. Which then shocked/sheared/stood open and took out the intakes on the next few revolutions. Chain reaction type of deal. I and many I know have bent plenty of valves through the years and they never twist rods like that at low rpm startups. Even higher rpm valve breaks usually just chew on pistons and cylinder walls while spitting valves out the exhaust ports without completely taking out the rods. Like a few others already eluded to.. it usually takes hydro-locks to twist parts up like that at such low rpm. And when you consider that fluids are incompressible(which is why jacks and hydraulic cylinders can practically lift the world).. rods can turn into pretzels and bad memory paper weights. As for luck and all that.. it's a mechanical thing and just got pushed past its limits till something went wrong. Some stock parts can take a beating.. and some of the very same part numbers cannot. That's just life with stock parts and why the stronger aftermarket stuff ends up being cheap insurance in the long run. Breaking parts and starting over teaches a valuable life lesson in persistence and fortitude. And since life will often get a hell of a lot harder than this little trivial speed bump.. they're good lessons to have under your kids belt. Keep on keepin' on.
I'm sure that revving it to 7k didn't help any either. In any case, 'just need to regroup and move forward. It's a temporary setback.
If it can't take 7k then it wasn't up to par with what we want anyway, also have had several professionals look at the rod and they see signs of a crack prior to the actual break, something to do with color, anywho I'm not going into specifics of what we are building but will unveil it hopefully by April, I'll give this much away, there will not be a single stock Ford part involved, thanks
