Time to go Stage II!
- Thread starter Alky V6
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In trying to make sense of why the number 2 main bearing is showing more distress than the other bearings, it made me recall a point brought up in a book in my library about the Buick V6 crankshaft differences.
"Since rod-journal diameter was increased from 2.0 inches on the odd-fire crank to 2.25 inches on the even-fire, thereby increasing the "over-lap" cross-section of the split pins considerably, there seems to be no real strength advantage in the odd-fire crank. As a matter of fact, when testing the new split-journal crank for durability, Buick designers noted that crank failures were caused by bending loads placed on the crankshaft nose by accessory drives, rather than torsional stress within the crank. It was discovered at the factory, and born out by some racers, that crank failures in the Buick V-6 almost always occur between the number one and number two main journals. This can be at least partially attributed to the placement of all accessory drives at the front of the motor, plus the extra length thereby necessary in the crank snout. The drives place a twisting (torsional) load on the crank, while the extra length in the snout increases the bending load (moment) at the belt drive pulleys. To remedy the problem, the designers added some material in the crossover sections of the even-fire crank, especially between the number one rod journal and the number two main journal. So the straight-pin, odd-fire crank really has no strength advantage over the even-fire, and might even be weaker (certainly more so than the rolled-fillet turbo crank). This point of concentrated bending loads on the crank snout should be given careful attention by all race engine builders, especially in applications that require additional accessory drives on the front of the motor (e.g., dry-sump pump or blower-drive pulleys.)"
"Since rod-journal diameter was increased from 2.0 inches on the odd-fire crank to 2.25 inches on the even-fire, thereby increasing the "over-lap" cross-section of the split pins considerably, there seems to be no real strength advantage in the odd-fire crank. As a matter of fact, when testing the new split-journal crank for durability, Buick designers noted that crank failures were caused by bending loads placed on the crankshaft nose by accessory drives, rather than torsional stress within the crank. It was discovered at the factory, and born out by some racers, that crank failures in the Buick V-6 almost always occur between the number one and number two main journals. This can be at least partially attributed to the placement of all accessory drives at the front of the motor, plus the extra length thereby necessary in the crank snout. The drives place a twisting (torsional) load on the crank, while the extra length in the snout increases the bending load (moment) at the belt drive pulleys. To remedy the problem, the designers added some material in the crossover sections of the even-fire crank, especially between the number one rod journal and the number two main journal. So the straight-pin, odd-fire crank really has no strength advantage over the even-fire, and might even be weaker (certainly more so than the rolled-fillet turbo crank). This point of concentrated bending loads on the crank snout should be given careful attention by all race engine builders, especially in applications that require additional accessory drives on the front of the motor (e.g., dry-sump pump or blower-drive pulleys.)"
With the above quote in mind, it makes me wonder if the extra wear I'm seeing on the number 2 main is being caused by a certain amount of crankshaft whipping caused by the loads brought about by the accessory drives mounted on the snout of the crankshaft. In my case, the drysump pump is being driven some length off the end of the crankshaft snout.
Possible causes of the higher wear seen on #2 main;
1) Main saddle misalignment.
2) Bent or cracked crankshaft.
3) Improper journal surface.
4) Improper bearing clearance.
5) Corrosion due to oil contamination. Fuel, water, blowby, extended change interval.
6) Bearing change interval exceeded.
7) Dry starting wear.
8) Overloading caused from short bouts of improper combustion.
9) Dynamic crankshaft whipping. Crank snout loading?
EDIT: 10) Crankcase distortion brought about through the method of mounting the block to the chassis. (High horsepower application only) Thanks to Chris H. for bringing this cause to light.
The wear to #2 is really not that bad. The wear is down to the copper over less than 50% of the bottom shell, but is evenly placed and smooth. All of the journals on the crankshaft still look like they did when I first bought the crankshaft. I'm just being my usual overly cautious self. I'll post a pic as soon as possible.
Causes 1-8 are easy enough to check and correct. Number 9, not so easy.
Causes 5-8,... guilty as charged.
I have had some oil change intervals that were too long. 4 month interval versus every month.
This build was way overdue for an overhaul.
The car does sit sometimes for a month or longer between starts.
My search for the perfect tune with this build has taken me into dangerous zones, multiple times. Actually, looking back at some of the mishaps I've gone through, I'm awfully lucky the engine is looking as good as it is. Well,... I did break a ring.
1) Main saddle misalignment.
2) Bent or cracked crankshaft.
3) Improper journal surface.
4) Improper bearing clearance.
5) Corrosion due to oil contamination. Fuel, water, blowby, extended change interval.
6) Bearing change interval exceeded.
7) Dry starting wear.
8) Overloading caused from short bouts of improper combustion.
9) Dynamic crankshaft whipping. Crank snout loading?
EDIT: 10) Crankcase distortion brought about through the method of mounting the block to the chassis. (High horsepower application only) Thanks to Chris H. for bringing this cause to light.
The wear to #2 is really not that bad. The wear is down to the copper over less than 50% of the bottom shell, but is evenly placed and smooth. All of the journals on the crankshaft still look like they did when I first bought the crankshaft. I'm just being my usual overly cautious self. I'll post a pic as soon as possible.
Causes 1-8 are easy enough to check and correct. Number 9, not so easy.
Causes 5-8,... guilty as charged.
I have had some oil change intervals that were too long. 4 month interval versus every month.
This build was way overdue for an overhaul.
The car does sit sometimes for a month or longer between starts.
My search for the perfect tune with this build has taken me into dangerous zones, multiple times. Actually, looking back at some of the mishaps I've gone through, I'm awfully lucky the engine is looking as good as it is. Well,... I did break a ring.
The broken ring did score the cylinder enough that I don't think a simple honing is going to take care of it. It's going to need a minimal boring and honing. I want to keep the cylinder walls as thick as possible. I also have to check valve to cylinder clearance with the new heads and valve sizes. I may have to go with a large enough bore to get proper valve to cylinder clearance. Custom size pistons will be ordered. Going with a 1/16" Hellfire ring set.
I'm trying to decide what to do about the piston pins. I'm presently using stock diameter, thick walled Ti pins. I'm debating whether to go to a larger diameter Ti pin, or move to a larger diameter steel pin.
The crank and rods will be checked for cracks and straightness.
Note: HD aluminum alloy cam bearings: .003-.004" clearance recommended.
I'm trying to decide what to do about the piston pins. I'm presently using stock diameter, thick walled Ti pins. I'm debating whether to go to a larger diameter Ti pin, or move to a larger diameter steel pin.
The crank and rods will be checked for cracks and straightness.
Note: HD aluminum alloy cam bearings: .003-.004" clearance recommended.
RMI-25 cooling system additive is the bomb! The last cooling system change involved adding a bottle of RMI-25 to the cooling system, and I was pleasantly surprised by the shape of the cooling system during this teardown. I'm sold. It works as advertised.
I've been watching intently, but this is REALLY good info to know for the general community. I started using it too when I redid my cooling system last year and so far so good. Thanks for all the posts and good luck.
TA Performance. They have a choice of coated or uncoated. I've used the coated in the past. I feel comfortable with either set. The present set is an uncoated set. They are showing very little wear. Debating whether to change them or not. I'll see what the clearance looks like with the new Stage II cam before I decide. If it's within tolerance, I won't bother changing them out.
Come to think of it, Norbs, I think I did do something different with the cam bearings on this last build. Let me do some research on that, and I'll get back to you. I seem to recall something about a special high performance Clevite part number to use for the Buick V6.
Edit: I checked the build sheet and it was a Clevite cam bearing set that I used this latest time around.
Edit: I checked the build sheet and it was a Clevite cam bearing set that I used this latest time around.
Here you go, Norbs.
http://www.stealth316.com/misc/clevite-max-cam-bearing-perf.pdf
If you have trouble coming up with the specific part number for the Buick V6 application, I can get it for you at the shop. Edit: Clevite 77 pt# SH-1385 S (ref. Clevite technical bulletin TB-2063)
The main thing is to use a cam bearing made with aluminum alloy vs babbit. At high spring pressures (300 on the seat), the babbit material doesn't fair well.
Other companies to check out other than Clevite are Durabond and ACL.
http://www.stealth316.com/misc/clevite-max-cam-bearing-perf.pdf
If you have trouble coming up with the specific part number for the Buick V6 application, I can get it for you at the shop. Edit: Clevite 77 pt# SH-1385 S (ref. Clevite technical bulletin TB-2063)
The main thing is to use a cam bearing made with aluminum alloy vs babbit. At high spring pressures (300 on the seat), the babbit material doesn't fair well.
Other companies to check out other than Clevite are Durabond and ACL.
The cam bearings used in this last build were not grooved on the OD of the bearing shell. I have used the grooved bearings in the past and didn't have any problems with them, but I just can't get comfortable with the supportive shell of the bearing being grooved.
Another thing to note while we're on cam bearings. The wear at the six o'clock position that is normally expected on the front cam bearing when using a chain to drive the camshaft is not there with the geardrive. One of the reasons I chose to stick with the geardrive over a chain. Improved cam bearing life. Particularly the front cam bearing which is normally an annoying problem with the Buick V6.
Edit correction: I just checked and there is no oiling groove in the front journal of my Stage I camshaft. I now remember ordering the camshaft with the specification not to machine the groove in the front journal for more journal to bearing contact area, and with that, better front cam bearing life.
Edit correction: I just checked and there is no oiling groove in the front journal of my Stage I camshaft. I now remember ordering the camshaft with the specification not to machine the groove in the front journal for more journal to bearing contact area, and with that, better front cam bearing life.
The wear to the geardrive is surprisingly low this time around. I have to give credit to the oil for that.
When I first started using the geardrive years ago, I was getting more wear than what I'm seeing now. I started out using a different oil (Valvoline 20w-50 Racing), then switched to Pennzoil 25w-50 Racing oil. Also, at first, I didn't make any special effort to supply a pressurized feed of oil directly to the idler gear bearing. It's nice to see the changes I've made along the way have helped with the durability of the machine.
When I first started using the geardrive years ago, I was getting more wear than what I'm seeing now. I started out using a different oil (Valvoline 20w-50 Racing), then switched to Pennzoil 25w-50 Racing oil. Also, at first, I didn't make any special effort to supply a pressurized feed of oil directly to the idler gear bearing. It's nice to see the changes I've made along the way have helped with the durability of the machine.
So your feeding the distributor gear and idler gear with pressurized oil?
I'm not running a distributor. I'm running a belt driven drysump oiling system so I don't need to drive an oil pump through the distributor gear, and I don't require a cam sensor signal with the engine management system I'm using. The distributor mounting hole in the timing cover has been eliminated.
That is another problem wear point that I've eliminated from my machine. The cam gear drive of the cam sensor/oil pump. Running high oil pump pressures with the stock oil pump makes the distributor gear drive a problem wear spot. I suppose if one were still running the stock oil pump, spraying pressurized lube to the gearset would help.
I am feeding a small spray of pressurized oil to the geardrive idler gear bearing. I'll cover that in more detail later.
This is the back of the mounting plate for the camshaft geardrive unit. It fits flush to the front of the block. I machined a passage that directs the oil from the hole I drilled in the block to the back of the idler gear bearing. The passage is surrounded by an o-ring to seal off the passage. You can also make out a tiny thimble filter that I installed in the passage leading to the bearing. The thimble filter protects the hole that is behind it, and keeps it from becoming plugged by small debris. The hole behind the filter is very small and acts as an orifice to control the volume of oil going to the bearing.
All the heat marking surrounding the lower mounting bolt hole of the plate is due to the working of the position of the hole to create a tight slip fit for a few of the mounting bolts to more solidly locate the mounting plate to the block. This helps to keep the gear mesh clearances that I set up for the gearset unwavering during the operation of the gearset, even if a few of the bolts were to loosen. BTW, I've never had the bolts loosen up on me.
All the heat marking surrounding the lower mounting bolt hole of the plate is due to the working of the position of the hole to create a tight slip fit for a few of the mounting bolts to more solidly locate the mounting plate to the block. This helps to keep the gear mesh clearances that I set up for the gearset unwavering during the operation of the gearset, even if a few of the bolts were to loosen. BTW, I've never had the bolts loosen up on me.
Mocking the heads up on the block, it doesn't look like the valve sizes will be a problem with the bore size I'm using. There's plenty of room now, even before the bore job. The way the valves are positioned relative to the bore centerline with the Stage II heads makes a big difference in available valve to cylinder clearance.
It looks like a minimum of a .010" bore size increase will clean up the bores. The bore is presently 3.937".
Looking at the heads mocked up on the block has my mind going crazy with ideas for the intake manifold. Dang, these heads are beautiful!
It looks like a minimum of a .010" bore size increase will clean up the bores. The bore is presently 3.937".
Looking at the heads mocked up on the block has my mind going crazy with ideas for the intake manifold. Dang, these heads are beautiful!
Chris H. PM'd me and explained that he had a similar experience with the #2 main bearing. He attributed the wear to the use of the stock location motor mounts putting stresses on the TA block that ultimately caused the wear. That makes perfect sense to me. I suppose I'm going to need to install some motor plates.
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