Author Topic: oil starvation #2 rod  (Read 9181 times)

Offline busted bisquit

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oil starvation #2 rod
« on: October 19, 2017, 12:33:26 pm »
Posted this in another thread wander if anyone has any ideas on why it seems to be #2 rod that is being oil starved when these engines blow. The last few that I have seen blown it has been #2 rod that goes




Offline RPM

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Re: oil starvation #2 rod
« Reply #1 on: October 19, 2017, 01:18:37 pm »
In my 20+ years of racing, building and servicing Legends cars, I have heard all kinds of theories.

Theory #1: has always been "oil starvation" for the #2 rod. I have a hard time believing that theory...

If there was an oil starvation issue for #2, then there should also be the same problem for #1 since they both oil from the same oil galley. But #1 always looks fine.

Theory #2: The engine gets so hot, the case is flexing. This somehow puts undo pressure on the #2 rod and it spins the bearing.

How does the engine only flex in one specific area and cause that single rod to spin the bearing and the others are unaffected?
If there was that much "flex" why don't we break more crankshafts?

Theory #3: #2 is the "hottest" cylinder due to the way the engine is put sideways into the car. That additional heat causes excessive expansion of the rotating assembly, including the big end of the rod. This expansion allows the rod bearing to spin.

I guess that one just seems unreasonable, especially if the oil temps are controlled in the low to mid 200* range.

As far as I can tell, it is just one of those things. I have seen each and all rods hanging out of the engine. From #1 sawing the alternator off the engine to #4 blasting the clutch basket into pieces.

Randy - RPM


Offline busted bisquit

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Re: oil starvation #2 rod
« Reply #2 on: October 22, 2017, 10:50:34 am »
Thanks for the input I talked to GE Chapman yesterday and his theory is case flex. I have seen more than #2 rod out of the engines but it seems like I've seen #2 rod the most. His theory is the front clip flexing causing the case to flex also. I don't know if I buy into that but who knows I guess anything is possible.