As you can see in this chart,...
As you can see in this chart, the standard replacement main bearing for a Buick turbo is a heavy duty copper-lead piece which has a maximum load capacity of 12,000 psi. Merkel uses a Federal Mogul super duty copper lead bearing with a max capacity of 15,000 psi. This is crucial with a boosted engine that can generate severe forces on the bearings under acceleration.
Merkel likes to see no more...
Merkel likes to see no more than 2 thousandths clearance (1.5 is preferred) in the main bearings due to the fact that there are no 3/4 groove main bearings available for Buick V6s. (We should note here that 3/4 groove bearings should be available from Federal Mogul by the time you read this.) Oiling for the rods is very important in a Buick because six rods are doing the work of eight. Merkel says, "These engines don't see a lot of rpm so the important thing is to keep the main clearance tight to ensure adequate oil volume to the rod bearings. Typically a small-block Chevy will run a higher rpm to produce the same horsepower on the motor, so they need more clearance."
Here you can see how Merkel...
Here you can see how Merkel enlarged the oil hole in the main bearing shell to match the larger oil feed hole drilled into the block. As covered in Part 1, the oil feed holes in the number two and three mains were enlarged to 3/8 inch to improve oil volume.
After applying a film of moly...
After applying a film of moly assembly lube, the ARP studs are torqued down to 90 lbs.-ft. Once the fasteners are torqued, they must be loosened and re-torqued four more times. According to ARP, all fasteners should be torque cycled so they will produce a true and consistent clamping load throughout the life cycle of the fastener. The reasoning is that when a fastener is first torqued, there is more friction in the threads and this produces a false clamp load. After a few torque cycles, however, the clamp load becomes consistent.
Here's an important Buick...
Here's an important Buick tip you'll want to take note of. The application of a small amount of Permatex Ultra Blue across the rear main cap will prevent oil migration out the back of the block. Many Buick owners assume they have a bad rear main seal when it's actually coming from the rear cap.
This Buick V6 is a fairly...
This Buick V6 is a fairly low-buck piece that uses a forged TRW factory replacement piston and reconditioned stock rods. The forged TRW slugs are designed to take press-fit pins like the factory pieces (note the rod heater in the background), but are much stronger than a factory casting. At this point, all the rod/piston assemblies have already been balanced and their weights used to calculate a bobweight card for crankshaft balancing (see Part 1).
Jack Merkel has found the...
Jack Merkel has found the Speed Pro plasma moly rings (part No. R-10499-30) to show extremely consistent end gaps right out of the box. In this case, Merkel is looking for 20 thousandths gap and that's what he finds most of the time. It should be noted that the precision of the boring and honing process is largely to account for this accuracy. An increase in bore diameter of 1 thousandth will increase end gap by over 3 thousandths. We also found that Speed Pro is recommending more end gap in the second ring than in previous years. They have found this reduces inter-ring pressure which in turn reduces ring flutter and blow-by. Based on this recommendation, Merkel uses 20 thousandths end gap in the second ring as well.
Here's another insider Buick...
Here's another insider Buick tip: Federal Mogul makes two rod bearing sets for the factory cast-iron crank, part No. 6-3755AP and part No. 6-3755APA. The first is recommended by the factory as the proper replacement part but the second (6-3755APA) is actually ten percent wider (left) and has a much greater load carrying capacity based on the additional surface area. This is the one Merkel uses for all his Buick V6s.
Just like the main bearing...
Just like the main bearing clearance, Jack Merkel likes to see 2 thousandths clearance on the rod bearings in order to achieve adequate oil pressure. Prior to torquing the rod cap, the bearings are polished with oil and Scotchbrite.
Prior to installing the piston,...
Prior to installing the piston, it's recommended that you coat the rod bearings with break-in lube and the piston skirt and pin with motor oil. Make sure to protect the rod journal when tapping the piston in!
Merkel torque-cycles the rod...
Merkel torque-cycles the rod bolts three times at 50 lbs.-ft. as per the ARP guidelines for rod bolts. Not shown but equally important is the piston-to-wall clearance and crankshaft end-play. These should be checked and set at 4.5 and 6 to 8 thousandths, respectively.
The cam of choice for Merkel's...
The cam of choice for Merkel's street engines is a custom mild flat-tappet cam with 206* of duration and .447-inch valve lift. The 109* lobe separation of this cam might not sound wide enough for power-adder engine builders, but according to Jack Merkel it produces the most torque on the dyno.
Need we say it again? Always...
Need we say it again? Always degree your cam--do not assume that your timing chain and camshaft are 100 percent accurate. Our Buick cam was checked and found to be right on the money.
With the V6 Buick, the oil...
With the V6 Buick, the oil pump is integrated into the timing cover. As a result, all the lube feed and supply lines pass through the timing cover. Like all Buick engines before it, the Buick V6 is notoriously weak in the oiling department, so it pays to blueprint the timing cover in key areas. All of Merkel's engines go out the door with key mods to improve oiling. The feed and return passages in the block are larger than those in the timing cover (shown) so the timing cover holes are enlarged to match the block. A booster plate is also added to improve oil volume and the pump is blueprinted to reduce flow restrictions.
This little item is known...
This little item is known as a booster plate. Stock Buick V6s do not have a booster plate, so having one at all is a big improvement. The idea is to provide a fresh thrust surface for the pump gears, which have usually worn out the aluminum facing on the oil filter housing. Pressure is boosted by providing tighter clearances and by cutting the "back feed" within the pump itself. Merkel improves further on the booster plate by enlarging the passage on the pressure side to match the passage in the oil filter housing (right side, top hole).
Compare the stock oil filter...
Compare the stock oil filter housing to Merkel's blueprinted housing (right, pointer). The feed passage is deburred and ported for better flow. Merkel recommends that a "biggie" oil filter kit be used with this mod to further improve flow. This converts the oil filter from a PF47/PF52 to a Buick big-block PF24 which has far more flow capacity. This is good for an additional 3 psi of oil pressure.
One of the biggest complaints...
One of the biggest complaints from Buick guys is the leakage that comes from the original design rope seals at either end of the motor. Rather than use the replacement rope front main seal in the Fel Pro rebuild kit, Merkel uses a Federal Mogul No. 472319 which is a more durable, better sealing neoprene design. While we're on the topic of seals, we should mention that this engine was also upgraded to a neoprene two-piece rear seal from Fel-Pro (part No. BS 40613). This shot of the timing cover install does not show the cam thrust button which was upgraded from a plastic OEM piece to a steel roller ball bearing thrust button (Sealed Power, part No. MR-1874).
Often has it been said that the Buick Turbo V6 is a different kind of animal. This animal is not easily tamed, and more than a few engine builders have fallen victim to its idiosyncrasies. New Jersey race engine builder Jack Merkel specializes in these high-pressure over-achieving mills. He knows all the cool tricks, and what's better is that he doesn't mind sharing this expertise. In the first installment of Buick Power (May 2002), Merkel walked us through the machine work necessary to build a long-lived engine. In this issue, he will show us the finer points of short-block assembly.
"The single most important issue in building Buick V6s is verifying that the bearing clearance is correct. If you set up the bearings loose like a small-block Chevy, you'll be lucky to make it down the track more than a couple of times," says Merkel. "Turbo V6s produce tremendous low-rpm torque and that creates extremely high rod bearing journal temperatures. Since the rod bearings are fed by the mains, it is absolutely critical to keep the main bearing clearance tight. Otherwise, the mains will bleed off oil pressure and starve the rod bearings."
Connecting rod side clearance is another critical area often overlooked by novice Buick builders. Says Merkel: "Side clearance is very important. You want to have no more than .015-inches clearance. You will know this is the case because it sounds like a bad lifter or a solid cam." Merkel recommends measuring rod side clearance during assembly with a dial indicator or a feeler gauge.
High volume oil pumps are always a good idea in Buick engines, but you can't just slap in the pump and call it done. You must also enlarge the four main bearing holes or risk premature wear on the cam sensor, which drives the oil pump. Conversely, if you enlarge the holes without using a high-volume pump, you will have dangerously low oil pressure. Another oil pressure problem spot is cam bearing oil hole alignment. "Many builders incorrectly assume that the oil holes in the block are in the same location as Chevy motors. If they bothered to look, they would see this is not the case. The most critical cam bearing is number 1, as this is where the majority of oil pressure is lost. The position of the number 1 cam bearing is also critical to ensure sufficient oil flow to the driver's side lifters and valvetrain."
It is no secret that a double roller timing chain has many benefits when building a performance engine, but caution needs to be exercised here, too. "Buick used a silent chain timing set with a hard rubber tensioner. Many novices make the mistake of re-using this tensioner with a replacement double roller chain. The nylon quickly disintegrates and fouls the oiling system."
Perhaps the most hotly debated item in building a Turbo V6 is cam selection. "Camshafts are not that critical," says Merkel. "There are plenty of cars going mid-10s with the stock cam. This proves that you don't need a lot of cam. You are much better off under-camming one of these engines than over-camming it."
So there you have it. Study the accompanying photos carefully and pay attention to the details. Doing so goes a long way toward guaranteeing your engine a long life. Next issue: cylinder heads!
SHORT-BLOCK SHOPPING CART:
ARP rod bolts - part No. 123-6002... $122.77
ARP main studs - part No. 123-5401... $64.95
Pro Gram Engineering billet main caps - part No. B4.1V6C... $199.95
TRW forged pistons - part No. L2481F-30... $469 per set
Speed Pro plasma moly rings - part No. R10499-30... $140.47
Fel-Pro two-piece neoprene rear main seal - part No. BS-40613... $22.23
Federal Mogul main bearing - part No. 107M... $94.29
Federal Mogul rod bearings - part No. 6-3755APA... $32.57
Federal Mogul cam bearings - part No. 1755M... $14.36
Federal Mogul core plugs - part No. 381-8073... $9.24
Comp Cams custom grind cam - part No. 206/206... $200.00
Speed Pro timing set - part No. 220-3129... $71.01
Federal Mogul high volume oil pump kit - part No. 224-518-V... $44.86
Federal Mogul oil pump thrust plate - part No. 224-518TP... $14.69
TOTAL SHORT-BLOCK LABOR
(including machine work) $1900.00
Total short-block cost: $3400.39