Crank end play, destroyed converter, 408 nightmare

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when I was still a teen, my friend, Art and I were installing a turbo 350 behind a 327 we had swapped into his Chevy van. We couldn't get the trans bellhousing to seat against the block. Foolishly, we opted to use the bellhousing bolts to draw it in. We drew it in to about 3/8" or 1/2" away, when we heard this ominous metal resonating "sproing", and we suspected that was not kosher. We pulled it back apart, and found a busted front pump on the trans. That's when we learned the hard lesson about engaging the splines AND the dogs with the converter neck.
 
I have a friend that I believe didn't properly seat converter. I'm going to insist we jack up and crawl under. Unbolt converter. And reseat. I'm assuming 727 is like any trans? If seated should spin gears. If not? You would know by sound and inconsistent spin?
If the converter isn't seated and the trans to engine bolts are pulled up most likely the pump and/or pump gears will be destroyed. You generally don't get a second chance at this
 
If the converter isn't seated and the trans to engine bolts are pulled up most likely the pump and/or pump gears will be destroyed. You generally don't get a second chance at this
Yes. That has been established. My question. Is there a way to check with transmission already in place? His motor is not yet ready to fire. I said he needs to pull trans out and re-install. But if there is a way to check without removing??
 
if you push the converter rearward, and it is fully seated on both sets of splines and converter neck fully seated into front pump I believe there is a measurement from the bellhousing surface. It was in a factory service manual(possibly for a 70 Cuda), unfortunately I don't remember the distance. Maybe someone else can recall the measurement. I believe there is also a note in the FSM about an official tool you can employ to hold it in the proper position while installing the trans, which looked like something anybody could improvise without much effort.
For myself, I am just real careful when I install it, and am cognizant of making sure it doesn't slip forward during trans installation.
 
IIRC when I installed the converter in my 904 I was able to push it far enough that the converter housing just barely touched the bellhousing. If you/your friend can easily slide the converter away from the flex plate a solid inch or so it's seated. If it takes any effort to push it back it's not, you *might* be able to get it seated by rotating it around and pushing lightly but I've never tried it with the engine already connected.

Worst case you might try separating the engine/trans just enough without fully removing the engine to get some hands in the bellhousing. But it's something you really ought to make damn sure is 100% right the first time or like was said, instant kaboom.

I'm not very knowledgeable about auto transmissions compared to many others here but I don't think having the converter seated will turn any gears unless the trans is somehow shifted into gear which I don't think is possible to do without the engine running first.
 
.....My question. Is there a way to check with transmission already in place?.....
Not confirmed number but seen a dimension on a transmission site said 1-1/4" from the bell face to the ring gear. Dammed if I can find it again though.
Lol, Turn the volume up on this if ya' dare...…
 
Yes. That has been established. My question. Is there a way to check with transmission already in place? His motor is not yet ready to fire. I said he needs to pull trans out and re-install. But if there is a way to check without removing??


As mentioned above, you can unbolt the converter and slide it back into the pump. The converter SHOULD slide so far back it damn near, or even touches the case. I say it may or may not touch the case because of dimensional tolerances. But if it doesn't touch the case it better be damn close.

If you are lucky (I'm not) you might be able to grab the converter and spin it a bit while trying to push it back and it MAY go back into the pump. I've never been able to do it. In fact, as a lesson to my friends who don't listen, when I catch what they've done, I make the pull the trans just so they learn to slow down and do it once.

Yes, I'm a prick and difficult to get along with. I don't like doing things twice. Especially when it costs money to do it wrong.
 
As mentioned above, you can unbolt the converter and slide it back into the pump. The converter SHOULD slide so far back it damn near, or even touches the case. I say it may or may not touch the case because of dimensional tolerances. But if it doesn't touch the case it better be damn close.

If you are lucky (I'm not) you might be able to grab the converter and spin it a bit while trying to push it back and it MAY go back into the pump. I've never been able to do it. In fact, as a lesson to my friends who don't listen, when I catch what they've done, I make the pull the trans just so they learn to slow down and do it once.

Yes, I'm a prick and difficult to get along with. I don't like doing things twice. Especially when it costs money to do it wrong.
Thanks. This was what I thought. And should be easy enough to alleviate my concern. Because I just saw this happen. To a Chevy friend's power glide. Pump shot and nice gouging around pump. All inside one block of driving. It sounded bad and was performing like trans was slipping. I don't need to see this twice to anyone.

All my road hot rods are or were manual transmission. (I just believe it brings a better "back in the day" experience.) So my auto trans experience is lighter. But I do remember my Vo-tech automotive class back in the 70s. And I was told explicitly not to bolt converter on first. So now I'm sounding alittle like a "Know it all" explaining. "I wouldn't do that." So thanks for confirming for me.
 
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Crankshaft is junk :/
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will disassemble the whole engine in the next time, also noticed the timing chain has really a lot of play in it.

Now im thinking of buying a complete new stroker kit with dished pistons and try to sell the pistons and rods i have - or ordering a complete new shortblock dont know yet
 
yikes, something ain't right for sure. Maybe the crank register was too shallow and the TC was holding it forward..
 
Ouch. That don't look good. If we can see from a phone camera pic? Probably worse is person. Starting over with a new short block build can be fun. (Except for the paying for it part.) Good hunting.
 
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Now I removed the timing set (had play on both sides), cam pistons and crank

the crank bearings look quite weird
 
were all the oil galleries in block AND crank thoroughly cleaned out with "gun barrel" brushes? seems like a lot of dirt/debris for 500 miles.
 
Ok, so the original issue was convertor failed, but engine always ran hot and detonated. Pull it apart and find blown head gasket and trashed bearings. My guess of the sequence of events. Either detonation or no retorque on those head gaskets pushed the fire ring to the valley or it ran hot and crushed the head gasket and then it failed. Not that uncommon in SB mopar. Why the R block has a fifth head bolt there. I assume you are running antifreeze which is very bad for bearings. If the converter wasn’t seated would it go 500 miles? I feel the converter failed then killed the thrust bearing in addition to the antifreeze. What did the oil look like? If those are icon flat tops, The icon 20.55 cc dish piston is about 10 grams heavier than the flat top. If the crank can be turned, I would turn it, buy the appropriate bearings. Buy the dished pistons and i would have it balanced. Reuse the rods. I would clean the block to within an inch of its life using bottle brushes then do it two more times! I would run a cometic head gasket. For your target c/r it is probably overkill, but I would still do it. I measure to determine bearing clearance, that being said I still double check using plastigauge. I can slide my converter back with the trans and motor together. I spin it a bit as it slides back.
 
I also noticed you are running main studs. Was the block align honed with the studs? It’s tough to see, but it looks like cavitation pits on the bearings.
 
Mind to share your thoughts about this? I cannot figure out for the life of it what antifreeze has to do with bearings.
I assume he was referring to the head gaskets leaking anti freeze into the oil. But frankly, I see no evidence of that, because the oil would look like a chocolate shake if that were the case. Don't ask me how I know that.
 
Yes, from the blown head gasket. I thought I asked what the oil looked like, but no.
 
Ok, so the original issue was convertor failed, but engine always ran hot and detonated. Pull it apart and find blown head gasket and trashed bearings. My guess of the sequence of events. Either detonation or no retorque on those head gaskets pushed the fire ring to the valley or it ran hot and crushed the head gasket and then it failed. Not that uncommon in SB mopar. Why the R block has a fifth head bolt there. I assume you are running antifreeze which is very bad for bearings. If the converter wasn’t seated would it go 500 miles? I feel the converter failed then killed the thrust bearing in addition to the antifreeze. What did the oil look like? If those are icon flat tops, The icon 20.55 cc dish piston is about 10 grams heavier than the flat top. If the crank can be turned, I would turn it, buy the appropriate bearings. Buy the dished pistons and i would have it balanced. Reuse the rods. I would clean the block to within an inch of its life using bottle brushes then do it two more times! I would run a cometic head gasket. For your target c/r it is probably overkill, but I would still do it. I measure to determine bearing clearance, that being said I still double check using plastigauge. I can slide my converter back with the trans and motor together. I spin it a bit as it slides back.

also think that the first converter who failed started all this and killed the thrust bearing and the crank (think its hard to see in the pics but the surface where the crank has contact to the thrust bearing has really deep grooves, there is so much material gone that causes the massive crank end play)

Yes there are icon flat top pistons in now.
Thought about selling them together with the rods and get a whole new balanced stroker kit with dished pistons, cause i think balancing is really expensive over here - paid 800€ to bore and hone the block.

What does the main studs have to do with the hone?


I will brush out all the oil and water galleries now and probably paint the block new.
What exactly do I have to pay attention to when i use a Cometic head gasket?
 
Hi, sorry for your loss.

Main Studs normally are tightened with more torque than stock bolts. Higher torque will distort the bore differently, so the mains should be honed after installing the mains and tightening with the desired torque.

Regarding the head Gasket: to me it seems that not all the bolts were tightened, seen this sometimes.

I also would change over to another piston....afaik Scat has got a kit with 20,5cc forged Pistons.

Michael
 
Probably wasn’t clear, not the cylinder hone. Studs can distort the main bearing bore alignment. Which if way off can be bored straight or it can be honed if slightly off. LA blocks seemed to be more susceptible to it than say a big block. My biggest worry is the surface finish. Cometic recommends a RA 50 for the block and head surface. I just searched and not that clear, but that may equate to 220 grit? Someone who knows better might chime in, but no issues for me, here’s my deck surface.

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