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Last Updated: 11/29/2007

1978-83 TURBO V6 NOTES

Below are some helpful facts and technical tips specific to the Buick NA (Normally Aspirated) V6. Most of the below entries are the results of question and answers from the Message Board. If you have a question not addressed here, have additional information, need clarification or disagree with something listed here, PLEASE post a message on the MESSAGE BOARD!

DISCLAIMER - Although I believe that the following are all true, please verify them before making any decision involving the restoration/modification of your vehicle. Some entries do not apply to all years/models. Also check with Federal/State laws before modifying or removing any emissions control devices.


WHAT'S NA? - If you don't know already, it means NORMALLY ASPIRATED. This refers to carburetion. The 3.8, 2-barrel, non-turbo V6 is usually called a 3.8 NA to distinguish it from the 3.8 Turbo V6. Fuel injection, while more "normal" now than carbs, traditionally was not called NA.

FREDDIE'S RECIPE - If you new to the Buick NA V6 and would like a "recipe" to follow, try this out.  BEFORE BLACK - NA Freddie's Recipe


CONVERTING A NON-TURBO V6 TO A TURBO V6? - If you have a normally aspirated (NA) Buick V6 and you want to add a turbocharger to it for some easy horsepower, please read "CONVERT TO A CARB/TURBO?" first. It's a little long, but it should be very helpful. Also read about an alternative to the factory draw-thru system; "CONVERT TO A CARB/TURBO? PART II?"

BUICK 4.1 LITRE V6 MOTORS - The Buick 3.8 and 4.1 are nearly identical with the exception of the bore. Also all NA 3.8's are 2-barrels, while all 4.1's are four barrels. Finding a Regal with the 4.1 V6 in the junk yard can be difficult. Here is a list of GM cars which used the 4.1 litre V6, courtesy of David Chase, Silver6.

ODD Vs EVEN FIRE - The first Buick V6 were the proverbial "V8's minus 2 cylinders". This produced uneven (odd) firing intervals. In mid-1977, Buick split the rod journals on the crank to produce even firing intervals. The easiest way to tell them apart is the distributor cap. An even-fire will have six towers, while an odd-fire will have eight towers with two blocked off. NOTE: An odd-fire engine will run, although very poorly, with an even fire cap.

LIFTER TICKING? - If you think you have a lifter ticking, first check for a cracked exhaust manifold or leaking gasket. These are very common problems on the Buick V6, and sound very much like a ticking lifter. It's worth a look and much, much easier to repair.


1981-1987 COMPUTER COMMAND CONTROL (CCC) - Since 1981 (1980 in CA), the Turbo V6 has used a Computer Command Control System (CCC) to control many engine functions. The Electronic Control Module (ECM) monitors and controls various systems that effect vehicle performance. The ECM can recognize some operational problems and alert the driver through the "CHECK ENGINE" light. A SCAN tool can be connected to the computer by using the ALDL port under the dash. The tool will display the output of various sensors (Oxygen, RPM, etc.) and display trouble codes. The codes can also be retrieve by grounding the test terminals on the ALDL port with a jumper (wire or paper clip). Do not buy "code readers", they just fancy (and very expensive) jumpers. This tech page from the Turbo Regal Web Site will explain more: GN/GNX/T-Type Malfunction Codes Codes for Carb/Turbo cars can be found here: 1981/83 ECM CODES

ELECTRONIC SPARK CONTROL (ESC) - The ESC system is what made the turbocharger practical for Buick's V6 application. The Achilles' heel to a turbo set up is detonation, or knocking. Under boost, detonation increases and will damage the engine. Most earlier and aftermarket system uses water injection to reduce detonation. Buick engineers developed the ESC system. The system uses a sensor to "listen" for knocking. When knocking is detected, the ESC retards the engine's timing to prevent it. The more knocking, the more retarding of timing, the less performance. To avoid knocking (and therefore maximize performance) use premium, high octane, fuel. The higher the octane, the greater the fuels resistance to detonation. See the KNOCK, KNOCK page for more detailed information.

TPS READINGS - The ECM uses reading from the Thottle Position Sensor (TPS) to determine how much the throttle plates are open and uses this to adjust the fuel mixture.  The TPS is usually set to some valve with the fast idle cam on the highest position.  My '83 Turbo V6 Quadrajet had the following readings:

Since the scale is linear, notice that the seconadies do not begin to open until 90% throttle movement.  At some valve (I wish I knew exactly), the ECM goes into WOT enirchment, mimicking a power valve's function in a non-electronic carb.  If the base setting is too low, the WOT may not be high enough to achieve enrichment.  The TPS setting also influence TCC lock-up.


EXHAUST MANIFOLD GASKETS - Buick V6 engines do not come with exhaust manifold gaskets. Most rebuilders, however, use them. After blowing out three gaskets, all at the number 2 cylinder (right, front), I quit using them. Instead, I use a very thin coat of Permatex Ultra-Copper. Just check the the mating surface on the manifold is in plane. If not, take it to a machine shop. More importantly, torque each bolt to proper specs and recheck often!



PRIME THAT PUMP ! - Any time the oil pump cover is removed, the pump will loose it's prime. It needs to be packed completely with petroleum jelly (Vaseline) before reassembly. Without it, the pump will not be able to pull oil from the pan the first time it is spun. Source: Jim Ruggles' Buick Stage One V6 Performance Guide, Petersen Publishing Company

BETTER LUBRICATION - For high performance applications, their are many different approaches to improving the V6's lubrication. Which is the best? Sorry, I don't know. They all have benefits and draw backs. It depends on your application. I suggest installing an oil pressure gauge to confirm adequate pressure, then research the options and pick which one best suits your needs. Good pressure and clean oil are most important. Some of the more common upgrades are briefly explained on this page: OILING SYSTEM UPGRADES.

OIL PRESSURE GAUGE - Your car probably has a simple "idiot" light instead of an oil pressure gauge. I recommend installing a high quality 0-100 psi gauge. They are very easy to install. I went with Auto Meter's Ultra-Lite 0-100 mechanical 2 1/16" gauge (#4321) which compliments the stock Buick gauges well..

"NORMAL" OIL PRESSURE - Everyone has different opinions about what the "normal" oil pressure should be. From the Jim Ruggles' Buick Stage One V6 Performance Guide: "These engines will idle at about 14 pounds of hot oil pressure." This is for the NA motor and prior to any modifications. Ruggles prefers 20-25 psi with a high-performance street Buick V6.


"ROCHESTER CARBURETORS" By Doug Roe- I highly Recommend this book. It explains the operation, repair, tuning and performance modifications of the Quadrajet and other Rochester carbs. Covers electronic and non-electronic carburetors. Published by HP Books, copyright 1981.

FOUR BARREL V6 INTAKES - If your have a 3.8 with a two-barrel carb and intake, this should be your first modification, in my opinion. A very good choice is a factory aluminum four intake and Quadrajet for a 4.1 V6. Many have electronic Quadrajets that can directly take the place of an electronic two-barrel. There are plenty of aftermarket intake. Find out about them before buying. Some don't have EGR provisions. Some are design for pre-'79 heads. And then some are for spreadbore carburetors. Some aftermarket intakes are made by Edlebrock, Offenhauser, Holley, Weiand and Kenne-Bell. (A junkyard 4.1 intake/carb has to be the best bargain.)

STAGE II V6 INTAKES - Stage II Buick V6 are factory high performance parts. They are very valuable and most find there way into very fast (read 9sec and faster) 86/87 Turbo Regals. There are quite a few Stage II four barrel intakes around (they were common in NASCAR racing). Since they are for carbs, and not SFI, they don't have the value of other Stage parts. But stay away from them, even if they are cheap. A Stage II intake cannot be used without the expensive Stage II heads. Production heads use an intake/exhaust valve arrangement of E I I E I E, while Stage II uses E I E I E I.

SECONDARY METERING ENRICHMENT - One way to richen the WOT mixture is to adjust the Quadrajet's secondary metering rods. This should not lead to an over rich condition at idle or part throttle, since the secondaries are typically closed. (This will work on the CCC-carb as well, because only the primary barrels are ECM controlled.) The secondaries' jets are fixed, but the metering rods can be swapped. They are easily changed by removing one screw that holds their hanger between the secondaries' air valves. Then just lift them out. Different rods have different size tips. According to the Rochester Carburetors book, thinner tips lead to a richer mixture. For drag racing, the author also recommends rods that have tips where the thin part is longer (all rods have same overall length). Rods are stamped with ID letters, but there is no pattern to the codes. The Rochester Carburetors book has a complete list of dimensions listed by ID code. The hanger itself can also be changed to adjust the mixture. The lower the holes on the hanger, the richer the mixture. In this case, the ID code has a pattern. The hanger should be stamped with a letter from B to V. B is the richest (highest hole) and V is the leanest (lowest hole). (Note: The Roe Carb book has this listed incorrectly) Not all rods and hanger are available from GM or aftermarket, so the best bet is to get them from a rebuilder or junk yard.

FUEL STARVATION? - I thought I was experiencing a fuel starvation problem until I read this in a GM training manual: "A poor performance comment may be received from a customer......on [quadrajet] V-6 engines....It may be described as running out of fuel when actually the engine is running too rich." This is opposite of what most would expect. The recommendation is to go to leaner secondary metering rods.

SPECIAL MANIFOLD BOLT - "On those Buick V6 engines equipped with the large diameter HEI integral coil distributor, a clutch head bolt (Torx) is used for clearance purposes under the distributor. This bolt is readily seen once the distributor has been pulled." The Buick Free Spirit Power Manual by John Thawley, copyright 1980.

SECONDARIES NOT OPENING? - One of the most common sources of low power (or low boost on Turbo V6's) is that the Quadrajet's secondaries are not opening.  The secondaries are open via mechanical linkage, so the vacuum or load doesn't matter. When you are looking to see if the secondaries are opening, you are mainly concerned with the lower butterflies (throttle plates) in the throttle body, not the upper butterflies (air valves) in the air horn. Those should be held shut by spring pressure and easily opened with your finger (just make sure they aren't binding).

In the throttle body (base of carb) there are two shafts. The secondary shaft, when viewed from the driver's side, is green, with a slot, wrapped by a spring and have a black "pointer" sticking up towards 12 o'clock. When you work the linkage by hand, the pointer will move from 12 to ~3 o'clock. Notice the slot in the end fo the throttle shaft. It may not turn. If it isn't, then the throttle plates aren't opening, but this may be normal. As Scott mentioned, there is a lock out on the passenger side that keep the plates from opening when cold. You can either push it out of the way, or drive the car until warm. Then when you work the linkage, you should be able to see the slot move. The seconadries do not open until about 90% of full throttle. They are really only good for WOT blasts.




THERMOSTATIC AIR CLEANER (THERMAC) - The air cleaner is design to provide an incoming air temperature of about 115 degrees (F). A temperature sensor is in the carburetor elbow and is used to control a vacuum actuated damper door in the snorkel of the air box. This door on the snorkel blends incoming air with air heated by the right side exhaust manifold, via a very narrow duct. This improves winter weather driveability. Warmer climate and summer only driven vehicles can do without thus system. During WOT acceleration, the (carburetor) vacuum drops to zero and the door will slowly open to allow unblended air through the snorkel alone. There is an inline delay valve which could be remove for quicker opening of the damper door.


THERMOSTAT - The Buick V6 share the same thermostat as the Small Block Chevy, so there are a wide variety of temperatures to choose from. Do not removed the thermostat completely on CCC cars. The ECM needs the coolant warm to achive "Closed Loop".


200-4R OVERDRIVE TRANSMISSIONS - The 200-4R OD trans came in the Turbo Regals in 1983-87. The only Buick NA V6 Regal with the 200-4R that I am aware of is the 1984 with a 4.1 V6. The 200-4R uses a different crossmemebr than the non-OD transmissions. All Regal frames from 1984 and on have the correct frame braces for the 200-4R's crossmember.

  1st 2nd 3rd 4th (overdrive)
350 2.52 1.52 1.00 N/A
200-4R 2.74 1.57 1.00 0.67


REAR AXLE RATIO - Most Buick NA V6 Regals seem to have a 2.41 rear axle ratio. To check the ratio on RWD cars, jack up one wheel, rotate it two times, and count the number of time the driveshaft turns (or jack up both wheels and rotate them once together). The RWD cars should have a 2.41, 2.73, 3.08, 3.23 or 3.42. If you want to change, consider swapping complete rears, as it might be easier and cheaper.

LIMITED SLIP - To check, jack up both wheels, turn one and the other will turn in the same direction if it is positraction. Also, look for a tag bolted to the differential. Please note that Positraction is Chevy's name for limited slip differential.

DIFFERENTIAL - All NA Regals (and 1978-81 Centurys) use the 7.5" rear. A good source for lower ratio, limited slip and 22mm sway bars are 1983-87 Monte Carlo SS or other G-body cars. 8.5" Rears are much stronger (and much more expensive). Look for these under 1984-87 Turbo Regals (3.42) and Cutlass HO/442's (3.73).


FRONT SWAY BARS - Most NA Regals have tiny, 25mm, front sway bars. Finding a larger 31mm bar on a G-body in the junkyard is easy. You will just need new bushing and end links. The next step is finding a 36mm hallow bar from a 3rd genration Camaro/Firebird. It will bolt right in.

REAR SWAY BARS - Most NA Regals didn't come with rear sway bars. Finding a rear bar on a G-body in the junkyard is easy (sound familiar?). The largest is 22mm. Don't forget to get the mounting shims from within the lower control arms.

BOXING THE LOWER CONTROL ARMS - Wheel hop can easily be prevented by boxing the lower control arms. Procedures can be found on the Turbo Regal Website (See the links page).


SPID / RPO STICKERS - Can't find the Service Part Identification sticker under the decklid with the Regular Production Option codes? GM didn't start using the SPID stickers until 1984.

A-BODY vs. G-BODY REGALS - All 1978-87 Regals are essentially the same car. However, for 1981, the Regal's sheetmetal received an aerodynamic upgrade. The 1978-'80 Regals share all major sheetmetal, while the 1981-'87 are the same (with the exception of a header panel change for 1984). The 1978 Regal was designated an A-body, along with the Century. In 1982, the Century split from the Regal and became front-wheel drive. The '82 Century kept the A-body name while the Regal was now called a G-body. Many publications (GM and non-GM) tend to group the 1981 Regal with the 1978-'80 models because they share the A-body name. It is more appropriate to group it with the 1982-'87 cars, since it has more in common with them.

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