Author Topic: Stroker bearing failure (Read 33989 times) Tweet

GeorgeC · « **on:** January 06, 2008, 09:15:15 PM »

Guys, I'm looking for some opinions.

I've got a local friend's 1474 stroker motor here that spun all four rod bearings. The motor was professionally assembled by a well reputed big name shop, with a Falicon 5mm weld-up stroker crank and Falicon knife rods. I have NO idea what kind of bearing clearances the motor was set up with initially, but the owner was/is meticulous about oil changes and always changed the oil every two trips the track, and would also drop the oil pan, clean the pickup, and check for debris as well.

The motor had around 75 passes on it (maybe 10 with a small 25hp dry shot of nitrous) when it suddenly just lost power at the end of a pass, then didn't want to idle well. The owner thought he had a problem with the Schnitz timing retard box initially, so he disconnected it. After taking the Schnitz box off, the bike seemed to be just fine. Last night he went to do his first burnout and noticed that the bike seemed way down on power, so he shut it off there and loaded it up.

We pulled the motor today and broke it down, and like I mentioned above, found all four rod bearings absolutely trashed (along with all of the rod journals on the crank). The wristpins also do not seem to want to come out of the pistons (so I've just left them in for now). He's trying to figure out what route to take when the motor goes back together, but right now we'd both like to hear some opinions on what may have caused all four bearings to fail like this with no warning.

SLEEPERBUSA · « **Reply #1 on:** January 06, 2008, 09:19:06 PM »

I don't know why, but when it goes back together, I would consult with Dave O or Nick. They seem to be successful on keeping 5mm cranks alive.

Chuck Wilburn · « **Reply #2 on:** January 06, 2008, 09:22:09 PM »

Same thing happened to us once with a Falicon crank. They're not nitrided so I don't know if that's a contributor or not. Never had a problem with an APE which is nitrided. The crank we had only lasted a few passes- we set it up identical to any other motor. .002 on the clearance, really good oil pressure, etc...

GeorgeC · « **Reply #3 on:** January 06, 2008, 09:35:59 PM »

I don't want to point fingers, but this does happen to be the second Falicon weld up crank I've seen trash a motor...

Like I said, this particular one WAS NOT setup by me, but the other was. It was setup and assembled properly. The APE stroker crank in my motor is still working just fine, and I do believe the nitriding process done by APE is a big contributing factor in their cranks holding up so well.

Chuck Wilburn · « **Reply #4 on:** January 06, 2008, 09:47:02 PM »

Yeah, that particular crank I'm talking about had a fat main- bearing clearance was really tight. So, I took it to a local crank shop and had them polish it down. The crank wasn't nitrided so I figure no problem. Well, the machinist was amazed at how soft the journal was! He was like man, I'm glad I stoped and measured or I would have taken off way too much.... That kinda worried me but I thought hey, Falicon knows what they're doing- as long as it has clearance it will be fine. Well, needless to say, I haven't tried another one.

BRYAN · « **Reply #5 on:** January 07, 2008, 07:18:08 AM »

Falicon is notorius for these type of problems. Detonation could be an issue...... What type of fuel were you using? Rick Stetson at Harry's Machine Shop is the ticket to making strokers live. He align bores the cases and does some oiling mods. This is who we use as well as Dave O.

crazybill · « **Reply #6 on:** January 07, 2008, 08:40:43 AM »

as has been said falicon strokers are notorius for having short lives . I wont use anyone but APE for a weld-up .
Ricks case mods are more than worth the money ! contact him at Harry's machined parts .

SLEEPERBUSA · « **Reply #7 on:** January 07, 2008, 09:08:32 AM »

Anyone have a number for Harry's?

Nosgsx1300 · « **Reply #8 on:** January 07, 2008, 10:14:04 AM »

1-508-366-1455

GeorgeC · « **Reply #9 on:** January 07, 2008, 12:50:52 PM »

Motor was always run on MRX01 fuel, and had timing pulled when spraying (again, he wasn't spraying but about 24hp).

A Falicon crank won't be going back in it.

SLEEPERBUSA · « **Reply #10 on:** January 07, 2008, 01:46:04 PM »

George, do the cases have that oiling mod done that they were refering too?
Mine doesn't, but it WILL.
Falicon crank aside, the oiling mod HAS to help.

GeorgeC · « **Reply #11 on:** January 07, 2008, 02:43:32 PM »

Nope, no oiling mods on this one (nor on mine for that matter). I'm not convinced that it's an absolute neccesity, but you're correct in that it certainly wouldn't hurt.

TRNorBRN6001 · « **Reply #12 on:** January 07, 2008, 06:25:17 PM »

Just as a side note when throwing it back together maybe make sure it is de-magnetized as well. Also as another side not for novices such as myself, don't take it for granted that bearings are always properly
sized from the factory.

Entropy did a little interesting experimenting with the de-mag thing. Plus Karl can tell you how much he likes
Plastigauge.

GeorgeC · « **Reply #13 on:** January 07, 2008, 08:01:53 PM »

Never heard of demagnetizing one before.

I don't even know how I would go about doing that.

TRNorBRN6001 · « **Reply #14 on:** January 07, 2008, 08:13:11 PM »

Yep, i didn't either. It should be able to be done at a local shop where they do vat a magnuflux stuff.

Entropy can give a better scoop on it than myself.

Competitive Edge Racing Cylinder Heads · « **Reply #15 on:** January 09, 2008, 01:25:14 PM »

gnd111 · « **Reply #16 on:** January 09, 2008, 03:52:13 PM »

Seems strange since heat kills magnetization in itself...

entropy · « **Reply #17 on:** January 09, 2008, 03:54:47 PM »

I AM NOT claiming that demag-ing the crank NECESSARILY was causing the mottled, weird look of my rod bearings.
Some folks say that overloading them give that effect.

I work with a bunch of Mechanical Engineers of oilfield equipment; they looked at those pix and said immediately: "stray currents, from a magged crank , bad generator system, or its coming outa the ign system somehow"

All I AM saying is that on two builds, done 3 weeks apart, i installed all new rod bearings, carefully sized; everything else was same in the 2 builds.

A is the rod bearing set from the last 3 sessions at Andy's FactoryPro dyno, 120 steps total (from 4000 to 12000rpm)

B is the previous set which has about 120 Andy steps(from 4000 to 12000rpm) + 43 JohnnyCheese pulls to 12,200 (limiter)

Between A&B builds I had the crank demagnetized and ran a ground strap to the head. No other changes.

You tell me, is there a significant difference in wear patterns ???

All of my rod bearings have had those weird mottled patterns since Johnnycheese showed me what a rod bearing was about 4 years ago.

gnd111 · « **Reply #18 on:** January 09, 2008, 04:03:58 PM »

I work with ME's in the mining field. Don't seem like they know much at all...

Hopefully it fixes your problem though...

show2ime2000 · « **Reply #19 on:** January 09, 2008, 04:13:20 PM »

Get you some Cailco coated bearings in that thing too...They really help!

Busa Quick · « **Reply #20 on:** January 09, 2008, 04:30:40 PM »

Quote from: entropy on January 09, 2008, 03:54:47 PM

Between A&B I had the crank demagnetized and ran a ground strap to the head.

If your head doesn't have a good ground connection your piston is the next closes thing to transmit spark energy. People running High voltage high output spark systems in car engines have found that sometimes the spark plug will fire off of the piston. When this happens your crank can be the final conductor to ground and in doing so, your bearings get burned out in the process.

You didn't say where the other end of your ground was so, I suggest either connecting it on top of your engine ground cable connection or the best is directly to the negative on your battery.

Mark

entropy · « **Reply #21 on:** January 09, 2008, 05:01:37 PM »

Quote from: Busa Quick on January 09, 2008, 04:30:40 PM

Quote from: entropy on January 09, 2008, 03:54:47 PM

Between A&B I had the crank demagnetized and ran a ground strap to the head.

If your head doesn't have a good ground connection your piston is the next closes thing to transmit spark energy. People running High voltage high output spark systems in car engines have found that sometimes the spark plug will fire off of the piston. When this happens your crank can be the final conductor to ground and in doing so, your bearings get burned out in the process.

You didn't say where the other end of your ground was so, I suggest either connecting it on top of your engine ground cable connection or the best is directly to the negative on your battery.
Mark

"the best is directly to the negative on your battery."

Mark,
That is precisely what Chevron's top ME expert on big recip engines said

(so that's where it is attached)

Busa Quick · « **Reply #22 on:** January 09, 2008, 05:23:25 PM »

Cool!

Mark

midnight black man · « **Reply #23 on:** January 09, 2008, 05:45:20 PM »

apart from all that i would carefully check the oil pump...slightly faulty ones can cause instant pressure falls which in a time manner can ruin a perfect crank...have seen that happen many times...

whtrthanu · « **Reply #24 on:** January 09, 2008, 05:49:41 PM »

From what it looks like to me is that your having a problem with the rod rocking too much....its hard to tell from the pick coloring...
The outside of the bearing surfaces look to be more worn than the inside...Usually caused by detonating, piston hitting the head, too much side/side clearance on the big end of the rod...
just me 2 cents from what the pics look like

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Author Topic: Stroker bearing failure (Read 33989 times) Tweet