Recommendations for a crank-kit and flywheel?

Looking in a lot closer on my broken crank I am convinced the cause was overstressed assemblies. I really put a bite on my fan belts and the A/C was doing double duty that day. If only I could update it to a modern serpentine belt drive system with tension pully. Too bad Eric Fisher is'nt around anymore to give me some ideas :(.

Took a couple of pictures of the stuff Charlie sent me. The crank is in pretty good condition and just has a lot of casting flash. About three rod bearing shells were minorly damaged, (I've got a few same sized new ones around to compensate). :cool:

Now lets see how well I can deal with the bottom end. Getting old fellas...it's not the same anymore. :redface:
 

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Well I'm more than happy to help you Freddie. I didn't notice the bearings other than the ones I thought didn't look that good to me, but I'm really picky after all.
 
I dont think there is enough over all data on the even fire split pin crankshaft to truly understand whats going on.

theres something about that 120* firing timing..... its loads things differently. Im just having a hard time believing its the belts.... theres just too many blowers out there to say it is.

I reckon the NA cranks are getting brittle under turbo use...... there not tempered the same way.

A.j.
 
It's either that or metal fatigue. I've read enough out there that says that any N/A crank can hold up to the demands of a turbo, (yet a few others may not agree). However, one must take into consideration that the only thing on turbo cranks which is re-enforced are the rod and main journals, not the crank pins or throws, (so everything else on the turbo crank is exactly the same as an N/A crank). The journals were hardened due to the additional force engineers presumed may or may not be exerted on them by a turbo. Take a good look at the pics I posted. The journals are squeaky clean, no journal damage.

The split took place before the thrust bearing, (#2). I'm only hypothesizing that the greatest force is the pull up force of all the belts combined, and that would be were the most pressure would be applied, (were the split took place). The only severe damage I found was in the front main bearing. The force was great enough to snap the main bearing's cap pin that attaches to the register. The broken piece stayed embeded in the register and the bearing spun along with the crank, (I tapped the pin out with little or no effort).

I've read enough material in rebuilding the 3.8 that says this is were most wear takes place due to the pulling force of belt driven assemblies, (the front main). So it may very well be a good guess. Serpentine systems require less than 3/4 torque than v-belt assemblies and do way less wear and tear on the crank. This would add to the HP gains one is shooting for.

I would'nt worry about what blower assemblies you may be using in the future. Unless you include an A/C unit. That in itself requires ridiculous amount of torque. When these engine were made R-12 was the freon of choice. If you know anything about A/C, R-134 requires the engine to work twice as hard as they were intended for when they used R-12. So my little V-6's crank was being punished.
 
Freddie's Buick said:
It's either that or metal fatigue. I've read enough out there that says that any N/A crank can hold up to the demands of a turbo, (yet a few others may not agree). However, one must take into consideration that the only thing on turbo cranks which is re-enforced are the rod and main journals, not the crank pins or throws, (so everything else on the turbo crank is exactly the same as an N/A crank). The journals were hardened due to the additional force engineers presumed may or may not be exerted on them by a turbo. Take a good look at the pics I posted. The journals are squeaky clean, no journal damage.

The split took place before the thrust bearing, (#2). I'm only hypothesizing that the greatest force is the pull up force of all the belts combined, and that would be were the most pressure would be applied, (were the split took place). The only severe damage I found was in the front main bearing. The force was great enough to snap the main bearing's cap pin that attaches to the register. The broken piece stayed embeded in the register and the bearing spun along with the crank, (I tapped the pin out with little or no effort).

I've read enough material in rebuilding the 3.8 that says this is were most wear takes place due to the pulling force of belt driven assemblies, (the front main). So it may very well be a good guess. Serpentine systems require less than 3/4 torque than v-belt assemblies and do way less wear and tear on the crank. This would add to the HP gains one is shooting for.

I would'nt worry about what blower assemblies you may be using in the future. Unless you include an A/C unit. That in itself requires ridiculous amount of torque. When these engine were made R-12 was the freon of choice. If you know anything about A/C, R-134 requires the engine to work twice as hard as they were intended for when they used R-12. So my little V-6's crank was being punished.
Click to expand...

hmm..... I see your point....... but then again.... maybe we should just consider the fact its 25 year old parts.

A.j.
 
I may have been wrong....

I was wrong!! I'll take that back...the turbo crank was built to strengthened the pins and the throws based on what the definition of Rolled-Fillet is in engineering. What do you think?

http://en.wikipedia.org/wiki/Fillet_(mechanics)

That, and in my case it was a 29 year old part. Metal fatigue must of played a part too. :(

By the way, I did some more reading on my service manual and noticed that only the manual transmission flywheel/flexplate used cut-out holes to balance it. Mine has balance weights on it, (classic AT part from OEM).

So chances are that that flywheel you sent me came off of a standard clutched vehicle.
 
Freddie's Buick said:
I agree...but in my case it was a 29 year old part. :( Metal fatigue must of played a part perhaps. By the way, I did some more reading on my service manual and noticed that only the manual transmission flywheel/flexplate used cut-out holes to balance it. Mine has balance weights on it, (classic AT part from OEM).

So chances are that that flywheel you sent me came off of a standard clutched vehicle.
Click to expand...

lol.......

how does that work? how do you have a flexplate on a clutch?

plain and simple... thats a NA flexer plate. pulled it off of a 2bbl NA 3.8 I have as a core in the shop.

A.j.
 
dr_frankenstein said:
lol.......how does that work? how do you have a flexplate on a clutch?
A.j.
Click to expand...

:biggrin:....Duh...well my good old Buick service manual said that. Did'nt give it much thought. I regurgitated. Two types of flywheel, one is balanced by punching holes in it, the other is balanced by attaching weights to it, (mine)
 
Freddie's Buick said:
:biggrin:....Duh...well my good old Buick service manual said that. Did'nt give it much thought. I regurgitated. Two types of flywheel, one is balanced by punching holes in it, the other is balanced by attaching weights to it, (mine)
Click to expand...

lol.... i do that all the time.

yet I havent figured out which is worse.... buicks or women.

A.j.
 
Charlie,

How much history do you know about the crankshaft you sold me?
It seems that the rod pins are not .010, (they're more closer to standard).
Crank won't turn torqued down and plastigauge shows a big fat squashed clearance of .0015, (over-kill).

That's not a bad thing, but I hate spending more money, (I'll either have to have it cut down to .010, or buy new standard bearings....:mad:).

I'll have to measure perfectly to see what side I am at.
 
Freddie's Buick said:
Charlie,

How much history do you know about the crankshaft you sold me?
It seems that the rod pins are not .010, (they're more closer to standard).
Crank won't turn torqued down and plastigauge shows a big fat squashed clearance of .0015, (over-kill).

That's not a bad thing, but I hate spending more money, (I'll either have to have it cut down to .010, or buy new standard bearings....:mad:).

I'll have to measure perfectly to see what side I am at.
Click to expand...

It came as a complete "turbo" motor from a rebuilder in Dallas Freddie. It was supposed to be ready to go but when I tore it down I was suprised it wasn't as advertised to say the least.:redface: Other than that I know nothing about it.
 
Yeah when I miked up the rod pin it came out to 2.2410, meaning that it may of been polished but not undercut. :( If it measures 2.2387-2.2395 then the crank rod pin was undercut.

The rod bearings that came with the crank, ACL .010 won't work. (I spent three days prepping them up and now it looks like I'll have to store them). It did'nt make sense that when I torqued them down they were so tight I could'nt turn the crank.

The Plastiguage was so squashed the reading was way of the chart. Something was wrong. I just took your word for it and figured it had to of been undercut so I did'nt even bother checking it. Bad mistake on my behalf.

I'll have to settle for a very loose standard size and see if I can get my money back from Auto Zone for the Clevite .010's I bought from them. I would of traded them for a standard set, but they don't stock the Sealed Power 3755A's I'd like to try, (they're made of aluminum instead of babbit).

It's the cheaper route because to have it cut down would be more down time and more expensive than the bearings.:(

Man this sucks....I hate playing detective. Freakin' Ebayer's can be so full of crap. Luckily it's nothing that can't be resolved. It's just another hole in my wallet..:mad:
 
Well at least it's a good crank for you and I'm sorry I never checked everything out. Once again it teaches me to recheck everything from the machine shop to make sure it's good.:redface::frown:
 
The crankshaft from hell...

Due to economical reasons and extensive down-time, I opted not to have this crank cut down. Instead I installed standard bearings and my readings are mediocre at best:

Crank Pin No.1 = 2.2410, clearance .002
Crank Pin No.2 = 2.2400, clearance .007
Crank Pin No.3 = 2.2405, clearance .002
Crank Pin No.4 = 2.2400, clearance .007
Crank Pin No.5 = 2.2400, clearance .007
Crank Pin No.6 = 2.2405, clearance .002

The journal readings are accurate. The clearances are 'ball park' due to my usage of Plasigage.

Just in case, I may have to use 10W-30 or heavier oil. Possibly my oil pressure may not be what I'd like, but I won't know for sure until it's on.

Heavier oil should protect me from rod knock since some clearances are very loose and the others are very good. Heck, even the Buick chassis manual states; "If journals are in good condition and so are the bearings, clearances in excess of .003 should not be a problem".

Although I don't know if it's true, my engine rebuilding book also states that even competition engines run a little more clearance than .003. And this book has not steered me wrong in the 12 years I've had it.

So it's a coin toss. I don't like it, but my backs up against the wall this time.
 
The more oil pressure you have the more HP the pump takes! So dont think of it as you dont have high oil pressure, just that your making extra HP. :D

Plus, many a SFI car has gone faster than anybody here will go with a stock setup and im sure theres people that have worse clearances.

I wouldnt worry about it too much, but thats me.
 
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