Contour Enthusiasts Group Archives Forums General Troubleshooting what I found in my old SVT motor-

Originally posted by Horse:

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really easy- first of all the Cobra R ditched the powdered rods in favor of forged Manley rods because they knew the rods were junk. the Noble M12 GTO uses steel rods- also the its new M12 GTO 3R uses the 3L with the same turbo setup for 400 hp.

The connecting rods made of sintered metal are made from powdered metal forged together- sintered metal is notoriously weak. they are made in one piece and then the big rod end is broken so that it can be used around the crank without using a modular crank- which is VERY expensive and not as strong as a forging. when you get machined sintered metal around its large crank bearing that has been broken to split it around the crank, it is very weak. (remember we are talking in relative terms here) Forged steel for instance is a large quantity of either molten steel or an ingot of some type- which is then forged (smashed) into shape- the density and strength charictaristics of forgings are amazing! Sintered metal is a step above a casting but a step below a true forging.

when the rods are weak in their large end they will tend to "mutate" from a round bearing surface to an oval one. (again this is relative- mabey a few hundred thou) this change in shape does not allow the metal bearings to function correctly. for those who dont know the bearings are called a Plain Metal Bearing- or depending on the makeup they can be called Tri-Metal bearings. they are about 1/16 inch thick - almost like a metal shim- and when the big rod end ovals it bites the bearings- and spins them- this creates many many problems- if youll refere to my other post- youll see which bearing did what-

When I say the rod bites the bearing you must understand that the con-rod has two grooves and it does indeed hold the two bearing halves in place- they are stationary in the rod and the crank bearing surfaces rotate within the rod end- so when the rod end bites the bearings it presses them into the crank which actually spins the bearings- and the two little teeth that sit in the rod end grooves get wiped off by the rod - then there is nothing to stop the bearings from free spinning within the rod end, where they either get chewed up by the rod end or the crank. (or in my case two welded themselves to the crank journals and one chewed up a rod end, and one set got so chewed up they spun into each other spoon style, and continued to get eaten away.

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These powdered metal rods are made at the Lima Engine plant in Ohio. Their advantage is that they are all the exact same weight, so every single rod is balanced right after they are forged, since they pour exactly the correct amount of mass into the rod that is necessary.

The tangs on the end of the bearing locate the bearing in the journal, but it's the "bearing crush" that holds them in place. If you were to measure the diameter of the journal once the bearings have been installed and the bolts have been tourqued that the bearing is actually oval. This is again by design because the bearing interferance helps hold it in place. You'll notice that when new bearings are installed , they are a little larger than the jornal. That is by design. What causes a bearing to spin is oil starvation, or incorrect boring and honing of the journal.

Procyon and Horse - what's the signifigance of just eating rod bearings while leaving the main's intact?

Would oil starvation and/or "crank whip" eat up main bearings too? I thought a flexing/whipping crank would almost have to eat a main bearing first.

Procyon - I've always been a bit curious, do you know the specs that SVT sorts cranks too? Did they maybe select to a tighter (maybe slightly off nominal) tolernace that could make the SVT's statisticly more prone to spin a bearing under stress / oil starvation conditions, or is that stupid?

Originally posted by ScottK97SEMTX:

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Would oil starvation and/or "crank whip" eat up main bearings too? I thought a flexing/whipping crank would almost have to eat a main bearing first.

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In my opinion, oil starvation would affect the rod bearings first/and or the worst since they are last in line to receive oil. Recall the recent updates to the Duratec to address oil aeration. Your thoughts on crank whip primarily affecting the mains seems reasonable.

Originally posted by ScottK97SEMTX:

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Procyon - I've always been a bit curious, do you know the specs that SVT sorts cranks too? Did they maybe select to a tighter (maybe slightly off nominal) tolernace that could make the SVT's statisticly more prone to spin a bearing under stress / oil starvation conditions, or is that stupid?

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I don't know any specifics of the "hand picked" cranks but I can't see any handpicking causing increased rates of failure. They may pick bearing sizes closer to nominal but they already have 3 grades of main bearing sizes to compensate for that. The only other thing that I can think of would be to pick a slightly off nominal bobweight since the piston has a taller dome (more weight) But maybe they took a little bit of weight out somewhere else to match the regular 2.5 piston.

I think the only thing that makes the SVT more prone to failure is the increased power output and increase in owner flogging (not that there's anything wrong with that I think that most of the people on this board drive their Duratecs harder than the other 90% of the population. i.e. You always hear about the bad news.

like what you said-
I didnt see any evidence of problem with the crank mains- in fact they are in Perfect shape- the crank would be in perfect shape except that it will need at least one rod journal ground- ill have to get the other two bearings off their journals to see those- but as you said the SVT peopel did not hand choose the duratec cranks- our SVT motors are built on an assembly line not hand built like the cobra motors- but like was written most people dont drive thier cars like SVT drivers do- ill be the first to say - I drive my car like I believe its supposed to be driven - thats why I like it- also about the oil aeration and design issues Ford is now dealing with - my very good buddy was on the Roush team that did all the testing that uncovered all these flaws- I was the one who brought the news to CEG - also it is his opinion that it is the rods that are problematic- granted not in every case and some undoubtedly are holding up better than others- but he said the powdered rods are junk-

ps- I will have pics up as soon as I down load them from the camera-

Originally posted by Horse:

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our SVT motors are built on an assembly line not hand built like the cobra motors

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The Cobra motors may be assembled by hand but the heads, blocks, cranks, etc are all machined by the same machines. I doubt that the Cobra engine assemblers are going over a list of measurements and saying "No, I don't want this block", even though everything is within spec. The parts come from the machining centers and they put them together.

Personally, I don't think there is any difference in having someone hand build an entire engine vs. an assembly line. But that's not a discussion for this forum.

LMAO - you could be correct but then again look what I do for a living and ill show you a difference between hadn built and assembly line built.

so where are the pics?

so my buddies sony digital camera needs a special driver and I coudnt find it- but hopefully today ill be able to get said CD and install it.

Originally posted by Horse:

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LMAO - you could be correct but then again look what I do for a living and ill show you a difference between hadn built and assembly line built.

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I thought we were referring to the difference between Mustang Cobras engines vs. Contour SVT engines. That's what you referred to in your previous post.

you just said that you basically didnt see any difference between hand built and assembly line- well here is a pic of a car we just finished building:
puny small block

thats a 289 stroked to 347 with AFR heads and Weber 48mm IDA carbs making 430 Hp and 440 lbft. son dont tell me hand built and assembly line doesnt make a difference- now I know that this is an extream example but it illustrated the point.