why my gov surged and I couldnt win 1st place

Ouch!

 I sure as hell wouldn't use that engine builder again. Spend a few bucks and hire one who pays attention to the details ?!!

hahaha  Your in luck Garry I don't build for anyone but me .  A 25.00 rod 20.00 dollars labor to pull it out but the stuff it was hooked to priceless. A rod bent like that and still didn't have a worse finish than fourth place .  King compression just imposed  a tax On the good side it didnt break and the other three arent bent as bad. just weak rods  sometimes you find the weak link when you run HOT.

Edited by mlpankey - 15 Oct 2010 at 6:29pm

i wished it had ih gov weights i don't think they come apart as much as the ac gov weights do . I guarantee you if you polled the audience they would remember the ac over the rest. I am very competitive and can take a fourth place finish better when coming home with a broken tractor than I can  coming home with a running tractor and a fourth place finish.

Edited by mlpankey - 15 Oct 2010 at 6:52pm

yes we had a stallion thought we had it figured out  but s---- happens .  we will check the crank to see if its bent and look at some aftermarket rods  maybe titanium . I would like to see just how high she would turn then  . I am doing away with the Allis gov. weights also.  Until then we were needing a clutch to hold fourth gear and 18.4 /38 rubber to keep her hooked to the ground.

I am glad that the rod bent and didn't break . The show lets the spectators to close to the track. If it had sent shrapnel flying it could have been ugly . I am not talking about the repair bill on the engine either.

its good. moves alot of air

Edited by mlpankey - 15 Oct 2010 at 8:42pm

Gerald I believe in the laws of conservation of energy . I need a strong rod that dont take up alot of room and dont weigh a ton so the torque is not trying to push through the crank .

Edited by mlpankey - 16 Oct 2010 at 6:10am

Chrome moly steel is stronger than plain steel or cast iron. But I don't know what the original rods are either. My 19th edition Machinery's Handbook says rods are typically 1040 or 3141 steel. It doesn't show tensile strength or yield for those numbers. 1035 and 1045 are 83K to 96K tensile, 51K to 65K yield (1035), or 95K to 115K tensile and 62K to 80K yield for 1045. The range depends on the drawing temperature, probably on the heat treat too. 3140 is 103K to 175K tensile and 79-152K yield.

I think of chrome moly as SAE 4340. This book says its tensile strength ranges from 120K to 210K and yield 95K to 190K.

Yield strength is the load where the steel stops acting like a spring and takes on a permanent elongation from the stretch test. Tensile is where the elongation stops and it breaks. Comparing the best 4340 to the poorest 1035 the yield strength of the chrome moly rod could be 3 times higher for the same weight rod.

The bending strength of an I cross section is proportional to the yield strength and proportional to the moment of inertia of that cross section. For a rectangular bar the moment of inertia is bxhxhxh/12. Height cubed. Its similar for an I cross section taking away the two bars of air. The important factor is h cubed means increasing the height without change anything else gets stronger in a hurry. If a rod was 3/4 x 3/8" bar stock its moment of inertia would be .013. If it was 7/8 x 3/8 bar stock it would be .021 an increase of almost 59% for a height increase of 17%. Since its the fibers at the outside flanges of the I that take most of the load, the strength of an I increases faster for the same change in height. A fundamental of a strength of materials course I took nearly 50 years ago.

Gerald J.

I need a formula to equate how much energy is being exerted on the rod at a given rpm.

What kind of motor is this out of

Those rod stress details are probably in some text books on engine design, either for automotive or aircraft service. I do have such books in my library, but a big portion of my library is still in boxes and I don't know for sure where those books are.

Gerald J.

I was thinkin' down the same lines as Gerald... specifically on the alignment issue.

The 'energy' applied to the rod can be calculated at any specific angle, provide you have a whole pile of details, but the STRESSES applied aren't the same as 'energy'... it's the combined vectors of stress moments that caused the beam to yield.

The picture is kinda fuzzy, and you don't have a second angle, but from what I see, the yield occurred on two different planes... as Gerald noted, I think the fact that you had to loosen other rod caps suggests that at the time of failure, there was enough deflection in the crank to cause the EXPECTED rod thrust to be augmented by some unexpected sideways thrust... like trying to walk with a rotated knee... hence, down it goes.

And if that IS the case, there's really only two things I'd delve deeper into:  1) Is there some point in the crankshaft, where an incipient crack resides, that is allowing more deflection than the crank normally withstands (perhaps one that developed during the pull, and may be waiting to come unglued in the future?) or...
Is there just not enough crank support from 3 main bearings to take this kind of punishment?

One other thing to keep in mind (and I don't think it's the case but shouldn't be discounted), is that the rod's bending moment has equal opportunity to be exceeded both on compression AND power stroke... if there's a chance that your CR or timing advance was too far on THIS cylinder (or preignition), or the mixture was rich enough to hydraulically lock the piston slightly before TDC, the yield started, and was finished by the next stroke's event.

Trophies are cool!  (just kinda costly)

DaveKamp wrote: I was thinkin' down the same lines as Gerald... specifically on the alignment issue. The 'energy' applied to the rod can be calculated at any specific angle, provide you have a whole pile of details, but the STRESSES applied aren't the same as 'energy'... it's the combined vectors of stress moments that caused the beam to yield. The picture is kinda fuzzy, and you don't have a second angle, but from what I see, the yield occurred on two different planes... as Gerald noted, I think the fact that you had to loosen other rod caps suggests that at the time of failure, there was enough deflection in the crank to cause the EXPECTED rod thrust to be augmented by some unexpected sideways thrust... like trying to walk with a rotated knee... hence, down it goes. And if that IS the case, there's really only two things I'd delve deeper into:  1) Is there some point in the crankshaft, where an incipient crack resides, that is allowing more deflection than the crank normally withstands (perhaps one that developed during the pull, and may be waiting to come unglued in the future?) or... Is there just not enough crank support from 3 main bearings to take this kind of punishment? One other thing to keep in mind (and I don't think it's the case but shouldn't be discounted), is that the rod's bending moment has equal opportunity to be exceeded both on compression AND power stroke... if there's a chance that your CR or timing advance was too far on THIS cylinder (or preignition), or the mixture was rich enough to hydraulically lock the piston slightly before TDC, the yield started, and was finished by the next stroke's event. Trophies are cool!  (just kinda costly)

This motor has billet main caps and I would tend to think the crank is bent but the fact that the main caps didnt affect the rotation and the rod caps did kinda makes me think that the rods being bent created greater  cylinder wall side loading. I would tend to think  a bent crank would be seen in the mains also. All four plugs have the blue line on the ground strap just above the weld at the start of the 90 degree bend that alone tells me the timing advance was dead nuts as well as the white oxidizatin around the metal base stoping at the first thread tells me the fuel ratio was acceptable. Methanol is really acceptable to pre and post ignition. Dry block with head steam holes tapped and plugged no way for water from colant system  to hydraulic lock the thing . One rod manufacturer said that the only 2 things create a bend in the i beam . 1. crossed wired . wich wasnt the case .2 rod fatigue from prolonged abuse. I guess 40 to 50 years of service could be prolonged abuse. I cant argue either way on that. I can say that these 262 buda rods were used in 400 ci at 15.3 .1 cr. turning 3 to 5 grand at a hp rating double the oem 262.

Gerald J. wrote: To much load will bend a new rod if its not strong enough.  I think you will find the bores of the two other rods no longer parallel that there's a bend in the rod in the thin direction that caused the bearings to bind on the crank. One way to get that bend would be for the crank to shift more than the crank shaft thrust bearing should have limitied it (typically .010 end play) That's why we are concerned about the crankshaft and the block. Gerald J.

Thanks for the thoughts on this .I will give all the main bearings and rod bearings  thorough examination as soon as I get through this refueling outage .