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