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Hey.. everyone loves an engine failure mystery - Brand X #3061538
07/21/22 11:57 PM
07/21/22 11:57 PM
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Posts: 8,127
Detroit, MI
CokeBottleKid Offline OP
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Sooo this one has me a bit puzzled... Foxbody 302 build, has maybe 5-7k miles on it. Re-ring frankenstein build, block I got out of the junkyard and rotating assembly I got from another fox motor. Everything was cleaned properly, crank polished by hand and on lathe, block dingle ball honed, all clearances checked (bout 1.5-2 thou on mains and rods).

Had a vibration develop at 4k plus RPM recently so stopped driving it and took it out. #5 main is toast, all the rods are fine though, none of the bearings look great but #5 is definitely the culprit. Usually with oil starvation a rod dies first so not sure what to think about this one, it clearly is a 50z crank and I had 50 oz weights on the flywheel and balancer... (SB fords have a 28oz and 50 oz external balance depending on year etc)

2 things that stick in my head:

1 - The starter bendix sticks for a couple seconds after starting then retracts... This actually started with the last motor (which blew up) I actually had drilled the starter holes out when I first put this motor together to get the bendix to return properly, just firing the bendix manually with a "lone wolf 3000" it would pop back immediately but when the motors rolling it takes a couple seconds... But perhaaaps it has been shoving the crank into the main during cranking...

2 - I had raced some audi looking mercedes a couple nights before the vibration developed... it was a deep freeway pull soooo it's possible the pan was sucked dry... that said it was full on oil, and I'm only spinning it to 6k on with a stock oil pump and pan... surely stock SBFs can handle 6k with a stock pan/pump right? laugh It's always been my experience though that rod bearings die before mains sooo *shrug*

IMG_5532.JPGIMG_5546.JPGIMG_5555.JPGIMG_5547.JPG
Last edited by CokeBottleKid; 07/22/22 12:00 AM.
Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3061568
07/22/22 09:07 AM
07/22/22 09:07 AM
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Windsor, ON, Canada
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Diplomat360 Offline
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I know nothing about Fords...but did you check the bearing clearance on EACH journal? Crank is straight, yes? So runout was checked and in-spec?

Beyond this, perhaps looking at restrictions in the oil feed is the next place to go? What does that routing look like on the 302? Where in that feed sequence is #5: start or end?

Last, visually it just looks to me like #5 was simply too tight, or there was a pile of dirt that got dumped into that somehow??? (maybe stuff was trapped in the oil feed passage and when things came up to pressure it all went straight out)

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3061586
07/22/22 11:00 AM
07/22/22 11:00 AM
Joined: Oct 2003
Posts: 11,329
W. Kentucky
justinp61 Offline
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The .0015-.002” on the mains would concern me, I run more than that on my rods. Remember what Monte Smith always said, “build a loose engine, only you’ll know, build it tight and everyone will know”.

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3061616
07/22/22 12:16 PM
07/22/22 12:16 PM
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Atlanta, GA
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mgoblue9798 Offline
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Originally Posted by CokeBottleKid
Sooo this one has me a bit puzzled... Foxbody 302 build, has maybe 5-7k miles on it. Re-ring frankenstein build, block I got out of the junkyard and rotating assembly I got from another fox motor. Everything was cleaned properly, crank polished by hand and on lathe, block dingle ball honed, all clearances checked (bout 1.5-2 thou on mains and rods).

Had a vibration develop at 4k plus RPM recently so stopped driving it and took it out. #5 main is toast, all the rods are fine though, none of the bearings look great but #5 is definitely the culprit. Usually with oil starvation a rod dies first so not sure what to think about this one, it clearly is a 50z crank and I had 50 oz weights on the flywheel and balancer... (SB fords have a 28oz and 50 oz external balance depending on year etc)

2 things that stick in my head:

1 - The starter bendix sticks for a couple seconds after starting then retracts... This actually started with the last motor (which blew up) I actually had drilled the starter holes out when I first put this motor together to get the bendix to return properly, just firing the bendix manually with a "lone wolf 3000" it would pop back immediately but when the motors rolling it takes a couple seconds... But perhaaaps it has been shoving the crank into the main during cranking...

2 - I had raced some audi looking mercedes a couple nights before the vibration developed... it was a deep freeway pull soooo it's possible the pan was sucked dry... that said it was full on oil, and I'm only spinning it to 6k on with a stock oil pump and pan... surely stock SBFs can handle 6k with a stock pan/pump right? laugh It's always been my experience though that rod bearings die before mains sooo *shrug*



Did you take the new oil pump apart and clean it out prior to the build?

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: justinp61] #3061649
07/22/22 03:06 PM
07/22/22 03:06 PM
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NY
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B1duster Offline
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Originally Posted by justinp61
The .0015-.002” on the mains would concern me, I run more than that on my rods. Remember what Monte Smith always said, “build a loose engine, only you’ll know, build it tight and everyone will know”.


I like that !
Not sure who coined it but there’s also “ Loose is Fast “

Last edited by B1duster; 07/22/22 03:08 PM.
Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3061662
07/22/22 03:47 PM
07/22/22 03:47 PM
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Bend,OR USA
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Cab_Burge Offline
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that looks like crank to bearing rubbing, not enough clearances or not enough oil flow on start up twocents


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: Cab_Burge] #3061683
07/22/22 06:10 PM
07/22/22 06:10 PM
Joined: Jan 2003
Posts: 8,127
Detroit, MI
CokeBottleKid Offline OP
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Quote
I know nothing about Fords...but did you check the bearing clearance on EACH journal? Crank is straight, yes? So runout was checked and in-spec?

Beyond this, perhaps looking at restrictions in the oil feed is the next place to go? What does that routing look like on the 302? Where in that feed sequence is #5: start or end?

Last, visually it just looks to me like #5 was simply too tight, or there was a pile of dirt that got dumped into that somehow??? (maybe stuff was trapped in the oil feed passage and when things came up to pressure it all went straight out)


Yes all clearances checked, crank straight? dunno but the motor it came out of had bearings that were like new.

#5 is at the end... so ya oil starvation is a possibility.

Block was cleaned pretty thoroughly so kinda doubt the dirt theory

Quote
The .0015-.002” on the mains would concern me, I run more than that on my rods. Remember what Monte Smith always said, “build a loose engine, only you’ll know, build it tight and everyone will know”.


I mean it was that after polishing to b00t *shrug*

Quote
that looks like crank to bearing rubbing, not enough clearances or not enough oil flow on start up


Well clearly it rubbed at some point, 0.00175 shouldn't be toooo tight tho, was primed before start-up and also had plenty assembly lube.

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3061687
07/22/22 06:56 PM
07/22/22 06:56 PM
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So Near, Yet So Far
topside Offline
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I think there are 2 or 3 different external balance specs on the SBF, aren't there ?
Never had my stock '89 5.0 to 6,000 - ran out of pull long before that.
.0015 sounds too tight to me, regardless of make & size.

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: topside] #3061690
07/22/22 07:13 PM
07/22/22 07:13 PM
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Super Spudsville
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I agree with topside, they were done well before 6k, more like nose over just under 5500 and go figure ford replaced my 86 5.0 Capri motor twice for bearing related issues and 3 T5 transmissions as well. Fun cars but the stock parts pushed always seemed to catch up sooner then later. A cat delete, 3.70 rear gear and comp ta tires and things would start to break soon after.


STOP POTATO HATE!
Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: Mr PotatoHead] #3062450
07/25/22 02:35 PM
07/25/22 02:35 PM
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Shelby Twp. Mi
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You need .003 minimum on mains! Also, possible you drained the pan which doesnt help. I think factory is 5 quarts. If you have aftermarket heads the drainback can be less than OEM.

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: HardcoreB] #3062653
07/26/22 10:39 AM
07/26/22 10:39 AM
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Ohio
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I agree with the clearances being too tight, my first engine had .0025 on the rods and
spun a bearing on #7, rebuild now .003 and no problem....yet.

Joe

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: topside] #3065058
08/04/22 02:12 AM
08/04/22 02:12 AM
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Detroit, MI
CokeBottleKid Offline OP
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Originally Posted by topside
I think there are 2 or 3 different external balance specs on the SBF, aren't there ?
Never had my stock '89 5.0 to 6,000 - ran out of pull long before that.
.0015 sounds too tight to me, regardless of make & size.


There is, 28 and 50, this is a 50 and it had the right ones

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3065059
08/04/22 02:13 AM
08/04/22 02:13 AM
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Detroit, MI
CokeBottleKid Offline OP
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You guys are crazy, .003" crank bearing clearance? This isn't the titanic laugh

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3065060
08/04/22 02:47 AM
08/04/22 02:47 AM
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Bend,OR USA
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Originally Posted by CokeBottleKid
You guys are crazy, .003" crank bearing clearance? This isn't the titanic laugh
How big is the O.D. on those mains?
The standard race clearance standard is .0010 per one inch of journal diameter, rods, mains or cam journals up scope
There are way to many internet and forum racing experts that have only raced on their keyboards, most of their "knowledge" is based on reading or hearsay, no real world at the track or dyno testing and racing tsk work
I was told years ago by a Ford SS drag racer, Ted Wells(he race 1967 a 410 HP 427 C.I. side oiler motor that he shifted at or above 8800 RPM shock up), to run a little more clearances than the recommended minimum if i wanted my NHRA Street 426 Hemi stock class race motor to live, he was correct up .
I've used 0033+ on the mains and .0030+ clearance on the rods long before you bought that Daeco race drum from me with no bad results on hundreds of street and strip and drag race only motors,Hemi, RB.B and lots of SB Moparswrench up twocents
Yuu will never spin a bearing with those oil clearances, you may with less than .0010+ per 1 inch of bearing I.D. diameter on the clearances tsk twocents

Last edited by Cab_Burge; 08/04/22 02:51 AM.

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3065094
08/04/22 09:46 AM
08/04/22 09:46 AM
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W. Kentucky
justinp61 Offline
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Originally Posted by CokeBottleKid
You guys are crazy, .003" crank bearing clearance? This isn't the titanic laugh


Says the guy with an engine that ate a bearing. whistling

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: justinp61] #3065148
08/04/22 12:12 PM
08/04/22 12:12 PM
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Detroit, MI
CokeBottleKid Offline OP
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Originally Posted by justinp61
Originally Posted by CokeBottleKid
You guys are crazy, .003" crank bearing clearance? This isn't the titanic laugh


Says the guy with an engine that ate a bearing. whistling


True, still say it wasn't the clearances tho... :P

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3065217
08/04/22 03:25 PM
08/04/22 03:25 PM
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north of coder
moparx Offline
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the saying goes : "no one will know if the clearance is too loose, but they will surely know if it's too tight". or something like that. biggrin
beer

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: moparx] #3065275
08/04/22 06:06 PM
08/04/22 06:06 PM
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Detroit, MI
CokeBottleKid Offline OP
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Well that's not quite true, it has a ton of clearance now and you definitely know it laugh

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3065286
08/04/22 07:04 PM
08/04/22 07:04 PM
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dvw Offline
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How do you know? If it has enough pump volume the pressure shouldn't suffer much. And then its usually at idle. That factory Ford crank probably looks like spaghetti noodle under heavy power. It been proven many times. Clearance is clearance. If there's lack of lube or flex, parts touch. Then the bad stuff starts. Open the clearance until they don't touch. Provide enough clean oil to keep them separated. That's the bottom line.
Doug

Re: Hey.. everyone loves an engine failure mystery - Brand X [Re: CokeBottleKid] #3065288
08/04/22 07:09 PM
08/04/22 07:09 PM
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Looks pretty clear to me it was an oiling issue....No way no how I would run the clearances that tight for sure. Not 100% familiar with windsor oiling but if you really think it wasnt a bearing clearance isseu(which is hard to believe)then I woudl start looking there as to where oil travels in the engine. Hard to tell from pics but looks like it had plenty of "stuff" going through it too, but could just be the pics and lighting.


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