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Hydraulic Roller Valvetrain Install - Turbo Buick Basics, Part 5 - Tech
Rebuilding The 3.8L V-6 And Switching To A Hydraulic Roller Valvetrain In The Quest For Lower E.T.'S And Years Of Enjoyment
Nov 18, 2010
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Hydraulic Roller Valvetrain Install - Turbo Buick Basics, Part 5 - Tech
Initially we planned to pull the motor at the owner's shop (Shore Wheels, Tuckerton, NJ) and clean up the engine compartment while your author performed an easy cam and head swap. Our friends Dan Smith and Jose Torres of Jose Motor Sports suggested we bring the engine to them to freshen it up. We took their expert advice and brought the motor to their nearby shop. When we dropped off the Turbo Buick V-6, Jose and Dan were ready to give it a teardown inspection just in case we needed to order extra parts. Here Jose pulls off the intake and heads. Sharp-eyed readers will notice the valvesprings from Part 2 of "Turbo Buick Basics." The stock heads would be exchanged for the ported and polished set that Jose spent many hours (30-plus) working on for us.
It's obvious this motor was never neglected when it came to regular oil changes. By 1987 the GM V-8s had roller lifters, but not the TB V-6. If the TB had a roller cam at the time it would have beaten-up more than just Mustangs.
The stock dished pistons were in good shape and would be cleaned-up and reused. We elected not use new lightweight pistons and rods, which could add power and would in turn skew our test results of the swap to the roller cam and ported heads.
Once Dan removed the timing case cover we could see the original timing chain and gears (notice the nylon cam gear teeth) were still in place and intact. That alone told us how well cared for this TB motor was. Here the cam button and spring is removed. The cam button rubs against the timing cover (see the impression). High mileage motors are known to wear a hole right through into the coolant passage at the water pump side of the cover. That would spell disaster (coolant leaking into the engine's oil) and possible death to the Buick V-6. We immediately ordered a new timing cover from our friends at G Body Parts.
The rods and mains were checked and fortunately showed minimal wear. Afterwards Dan measured the crank's mains and rods. They were still standard size; therefore the crank would only need to be polished.
There was evidence of some blow-by, combustion gas getting past the rings, which is typical of a forced induction type motor when the boost is turned up. The pressed-in pins would stay in place (they checked out OK) while the rods were resized to accept stock size bearings. New Sealed Power rings (0.005-inch over) would reside on the stock pistons after a thorough cleaning, and they were checked for cracks. First the rings would be file-fit and gapped at 0.018-inch in the lightly honed cylinders (0.005-inch over) before being installed on the pistons.
The little V-6 ran well before teardown and we didn't anticipate any issues. Once the block was hot-tanked and cleaned up, Dan said the specs in the cylinders and mains were "on the money." The LC2 block is a rugged little piece, but like most production blocks there's a limitation to the amount of safe boost and horsepower they can handle. In this case, that would mean single digit e.t.'s, so we don't plan to exceed those limitations.
This is the original numbers-matching block to Tim's '87 Grand National and we're confident it will be built right for years of miles and smiles. The '87 crankshaft is known to be stronger than the previous year's and will hold up to our intended safe, street/strip style buildup. The oil pan will be cleaned-up, painted, and put back in service. The heads will be exchanged for the Jose-ported set we'll use and he'll put them in stock to port for a future customer.
Jose did a killer job porting us a set of heads (more on this later). A set of well-ported heads are essential to letting more air breathe through the boosted V-6.
This hydraulic roller camshaft (PN 69-300-8) and lifters (PN 853-12) from Comp Cams will aid in moving much more airflow than the stock flat tappet cam. Jose Motor Sports says this cam has been proven in nearly 100 of its customer's engines, which accrue a substantial amount of street miles as well as passes at the strip. It features 0.504/0.504-inch lift, 212/212 duration at 0.050. Compare that to the wimpy stock stick that has only 0.400/0.422-inch lift, 193/196 duration at 0.050. With all that added lift and duration we should see a monster performance difference.
Part of the K-Kit from Comp is this quality Hi-Tech Roller Race timing set (PN 3129). It's a double roller chain with oversized rollers, triple index steel gear and is dynamically balanced. It will keep all the timing events in perfect order for many more miles than a stock replacement type set.
Another important part of the K-Kit is these Hi-Tech 5/16-inch diameter, 8.200-inch length pushrods (PN 7966-12). They are one-piece seamless 4130 chromoly tubing in 0.080-inch wall thickness for much more strength than stock. They'll work great to provide the proper lifter preload when used with the stock rocker arms.
More parts from the Comp K-Kit are Single Beehive Ovate valvesprings (PN 26915). They feature a seat load of 105 lbs at 1.800 and an open load of 293 lbs at 1.200. We upgraded to titanium retainers (PN 772-12) for less weight at the valve tip. Positive stop Teflon valve stem oil seals (PN 503-12) will be used-the heads would be machined for their use. Preventing the valves from dropping into the cylinders are machined steel, single groove 7-degree valve locks (PN 648-12).
Cometic high-quality gaskets will seal up the entire TB motor and prevent many types of leaks (vacuum, oil, coolant, compression, exhaust, etc.) from happening. Well known for its quality MLS head gaskets, we went for the entire engine gasket set: oil pan with rear main seal, timing cover, water pump, intake, exhaust, heads, and valve covers.
The cylinders were precisely honed 0.005-inch over stock to a 3.805-inch bore size. Deck plates were used to make the cylinders perfectly round with no-taper from the top to the bottom of each bore. This enables the rings to break-in more quickly to keep compression in the cylinder and combustion chamber for less blow-by to go through the crankcase, out the breathers and back into the PCV system. No fancy crankcase vacuum pump here-we want the TB to look bone-stock.
The machined block was reunited with its original crank, which was micro polished. Dan lightly line-honed the main caps so the Clevite standard-size main bearings would have a clearance of 0.0015-inch. Torco assembly lube (same as from Part 2) was used throughout the entire engine build. The main caps were torqued to 100 ft-lb. Crankshaft endplay came in at 0.007-inch. A new Cometic rear main seal was installed from the engine set. All of the oil passages were smoothed (polished) and cleaned out in both the block and the crank for a sufficient oil supply.
The hydraulic roller cam was installed straight up. After installing this cam in so many TBs, Dan mentioned it's not necessary to degree it. This proven stick will broaden the powerband by far when compared to the outdated, stock flat tappet cam. Previously, the peak torque to peak horsepower was at roughly 3,000 to 4,000 rpm. The added lift and duration of the new roller cam will measurably increase torque and horsepower while widening the power curve by roughly 1,000 rpm (we'll predict with a fair degree of certainty the peak to peak torque/horsepower should be around 3,500 to 5,500 rpm-after dyno testing we'll know for sure, stay tuned).
The bottom end was buttoned-up with the stock (resized) rods using Clevite standard size bearings and torqued to 40 ft-lb. Rod bearing oil clearance specs were 0.0018-inch and side clearance was 0.008 to 0.012-inch. Up on the rod's small end, the original cleaned-up pistons were fitted with Sealed Power rings-after the rings were file-fitted dead square in the cylinder bore and gapped to 0.018-inch. New freeze plugs and oil galley plugs completed the short-block package.
The block was square decked so the piston to deck height would be the same front to rear and from side to side. This also promotes a better seal for the head gaskets with the flattest possible deck (no warping-high or low spots on the deck). Notice the Comp double roller timing set with the oil slinger (in front of the crank gear) to keep the chain lubed and lesson the odds of an oil leak at the timing cover oil seal. The cam button and spring received a dousing of assembly lube right before the timing cover and oil pump were installed.
Here's the aforementioned timing cover we needed to order from G Body Parts. It comes bare and will house the oil pump, water pump, and cam sensor. Dan ordered a Melling high-volume, standard pressure oil pump kit for a sufficient oil supply to go through the engine and turbo.
After installing the oil pump kit, the timing cover was hung on the front of the short-block. It took a lot of precision machine work, cleaning, assembly, and patience to get to this point, but it will be worth the effort! As a reminder, for our type of build, we consider ourselves lucky we didn't have to buy a new rotating assembly (pistons, rods, crank).
Check out these before/after shots of the intake ports. Jose put in the hours (roughly 30-40) with his sculpting work (port-matching, pushrod area, bowl, short side turn, guide boss, etc.) so each port looks and flows similar. Your author has ported and flow-bench tested many sets of heads in the past. So I could see what an outstanding job Jose did streamlining and polishing the ports. By looking, it's safe to guesstimate peak flow improvements were at least 40 to 50 cfm, that's a big-time gain in airflow.
Looking at the untouched exhaust port, it's easy to see the guide boss and bowl ridges were intrusive to airflow. The same streamlining done to the intake ports was done to the exhaust. What a difference!
This is another before/after look at the extensive sculpting done to the guide boss and bowl. It obvious there will be much less restriction in airflow after Jose's handiwork.
As can be seen here, all the guides were treated to new bronze valveguide liners. The intake seats were opened up to receive a larger intake valve (exhaust will retain stock size valve). Here it's noticeable that the seat has more than the standard 45-degree valve job. Dan performed a 75-, 60-, 45-, and 30-degree cut to each intake port. Multi-angle valve jobs enhance low- and mid-lift flow that improves low-end torque, midrange and driveability.
The chambers were polished to prevent hotspots that accompany possible detonation. The heads were resurfaced 0.010-inch to ensure a flat seal to the gasket and deck. New stainless steel valves replaced the aging stockers. A 30-degree back-cut was performed on each intake valve's seat. A back-cut is known to improve flow at low and mid lift (0.200 to 0.300-inch). I've seen it improve flow by 7 to 12 cfm at 0.300-inch lift on many different types of heads. Intake valve size increased from the stock size of 1.700-inch to 1.775-inch for more flow and performance. On the exhaust, the valve size remained unchanged at 1.500-inch.
With so much cylinder pressure under high boost, we needed the best fasteners to hold the heads from lifting. TBs were known to blow head gaskets from running too lean under high boost (over 17 psi) with stock head bolts and gaskets. For extra insurance we ordered these high-quality ARP head bolts (PN 223-3703).
To set the spring height at 1.700-inch, Dan used 0.050-inch valve locks to raise the spring height to specs. Once the heads were assembled, they were bolted on and torqued to 80 ft-lb. Next, the lifters and pushrods were put in their place and coated with Torco assembly lube on all the contact points. Take note that Jose even ported the coolant passages for better flow.
Topping off the long-block is the sturdy, stock rocker arm shaft assembly. They are non-adjustable and after being torqued to 30 ft-lb, lifter-preload worked out to be around 0.030-inch. Like anything else, the right combination is everything. In the next episode, dyno and strip testing results should be interesting. We're confident that with Dan and Jose's TB experience, Tim will enjoy driving his GN more than ever before.
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