2.8 to 3.4 Liter Conversion FAQ

Overview:

The 2.8l sixty degree V6 engine was used throughout the First Generation S-10/S-15, Blazer/Jimmy production so it, understandably went through several updates and improvements. In normal GM fashion, not all the upgrades were made at the same time so this clouds the picture.

1982 to 1985 engines were carbureted and used a mechanical fuel pump. The rear main seal consisted of two parts and was prone to failure. The bearing journals were a weak spot and spun rod bearings were common. The front [timing] cover is machined for the water pump to rotate in the same direction as the crankshaft using multiple Vee belts to drive the accessories. This engine is externally balanced using weights welded onto the flywheel/flexplate.
Despite its shortcomings, many of these engines are still running and many have been turned into boat anchors.

1986 was a year for big changes. The bearing journal was increased. A single part rear main seal was added and the heads were upgraded to 1.72" intake valves and 1.42" exhaust valves. The biggest change was electronic fuel injection using a Throttle Body with twin injectors using an O.B.D. I computer and a fuel tank mounted electric fuel pump. Power increased to 125 hp. and 150 ft. lbs. The front cover is the same as the older engines and Vee belts were still used and the balance was still external.

1987 introduced the serpentine belt. This required the front cover to be machined to work with a water pump turning in the opposite direction from the crankshaft. The only visible difference between the front covers is the direction of the 'swirls' machined in the area behind the water pump impeller. This makes a difference in the coolant flow and an engine with the wrong front cover will have cooling problems. The belt tensioner is usually mounted with a #55 TORX fastener. The belt driven component brackets were re-designed to hold the components in a stationary position for the serpentine belt. This engine was still external balanced.

1988 is the introduction of internal balanced components. The flywheel/flexplate changed to a neutral balance assembly free of welded counter weights. The 2.8l stayed the same until it was discontinued.

60 Degree Evolution:

General Motors continued to utilize the 60 degree engine in various RWD and FWD applications. The most popular RWD vehicle was the Camaro/Firebird which used the 2.8l through 1990. In 1991 the engine was stroked into the 3.1l for a 10% increase in displacement. The block stayed the same and is a direct bolt in replacement for a 2.8l engine. In 1993 the block casting was strengthened and bored to 3.4l for another 10% increase. The FWD version made the same advancements and the D.O.H.C. 3.4 in the Grand Am shows how far GM took this design.


FWD vs RWD:

FWD engines are utilized in transverse mountings and have the starter mounted on the opposite side when compared to RWD engines. They utilize an aluminum head and intake that is not interchangeable w/ the RWD iron heads. It has a different bolt pattern & just won't work on RWD engines. There are people putting FWD engines into Fieros after modifying the starter mounting. It's possible to do the same for an S-10 but it is not recommended for the inexperienced. Stick to the RWD engine.

SOURCES OF 3.4l ENGINES:

The ideal used engine is the 93-95 Camaro and Firebird and they are readily available through the country. There is a web page selling them. Engine re-builders sell 3.4l long blocks setup for the Camaro. They should be able to make a 3.4l with the required changes to bolt into our trucks. This will happen if enough people, armed with the facts, start requesting engines made to fit.

GM Performance makes the HT 3.4l which they sell as a new, bolt in, long block for carburated 82 to 85 S-10 vehicles. Their advertising says it cannot be used on TBI applications because GM only emissions approved it for 82-85 automatics. This is due to each variety [auto & stick] need their own approval and the newer EFI units would need the same. They cannot recommend that you use the engine for an application that is a violation of the Federal Air Pollution laws. When you consider the requirements of installing the crate engine in an 82 to 85, it becomes clear that it is more suitable to the newer (EFI) vehicles.

The Crate Engine comes complete with the front cover for Vee belts, a 4x2 oil pan and the intake gaskets installed & the pushrods setup. Swap intakes, bolt on your externals & drop it in BUT you need an electric fuel pump because there is no place on the block to mount a mechanical fuel pump. Also 82 to 83's with a cable clutch need to change over to a hydraulic clutch system because there is no 'boss' for the clutch cable pivot. On top of that, the 3.4 comes with a neutral balance flexplate so you need a new flywheel if your 82 to 85 is a 5 speed. Now look at an 88 with a TBI; the fuel pump is already in the fuel tank, the flywheel is neutral balance, and the hydraulic clutch is in place. The only problem is the front cover needs to be swapped for the serpentine belt. The engine does not 'know' what intake is installed, it just wants a mix of air and gasoline vapors.

The Camaro engine is setup for the serpentine belt and it has been reported that using the camaro front cover, crank pulley & Camaro belt driven accessories makes it impossible to use the stock clutch fan. You will also need a smaller belt. This is OK if you are planning to add an electric fan. If you are on a budget, swap the front cover & use your 2.8 accessories and do the electric fan later.

The Camaro oil pan looks similar to the 4x2 oil pan. Looks can be deceiving, The Camaro Oil Pan Will NOT Fit Into a S-10!!!!! You need to swap for the 2.8 oil pan.

GENERAL FAQ:

Anyone with a 4X4 needs to swap the oil pan and pick up over to the 3.4 as the 4X4 has a different sump than the 4X2 and the Camaro.

Serpentine belt front covers will not work on Vee belt engines. The 86 is the ideal Crate Engine EFI swap as this year still uses the Vee belts.

TBI systems from 2.8l engines will run lean on a 3.4l unless you make some modifications. The HOLLEY bolt on TBI is larger than the 2.8 and supplies enough fuel for higher RPMs. A 4.3 TBI will fit but the throttle hookup is different. The best solution, so far, is to rebuild the 2.8 TBI with injectors from a 4.3 TBI to get the extra fuel. It is easier than a carb rebuild and is a lot less money than the HOLLEY TBI unit.

Some people have found cam wear in the donormaro engines. Always check out the engine & replace as many gaskets & seals as you can.

The Camaro engine can be re-cammed w/ a low-mid torque cam like the one in the Crate Engine. That's a good solution for camshaft wear.

Your 2.8l headers & other bolt on items will fit onto the 3.4l block.

Always prime the oil system in any 60 degree engine. The hex shaft under the distributor fits a 6point 8mm socket. Tape it onto an extension & use a hefty electric drill to turn the oil pump until oil comes up ALL the pushrods. Smaller drills won't have enough torque once the oil starts to fill the system.

You have to loosen the pushrods to install the intake gaskets. You tighten the rocker 1/4 to 1/2 turn after the slightest contact between rocker & pushrod with the piston @ TDC. Over tightening the pushrods can prevent the engine from starting.

TBI systems have (2) temperature sensors, one in the intake manifold and one in the corner of the driver's side head. The plug in the head has an 8mm square hole. This is hard to find. On a new crate engine, ROBO GRIP type pliers can remove the plug. Vise Grips won't. NOTE: the passenger side head has the same plug facing the firewall. This would be the ideal place to hookup an aftermarket temperature gauge.

The Knock Sensor screws into the water jacket on the starter side. On Camaro engines it is close to the motor mount and clears the starter. The crate engine only has one threaded block drain and it's close to the starter. They don't look like they would interfere when the engine is out & the exhaust manifolds are off. The plug won't hook up
to the knock sensor as the small wire on the starter solenoid is in the way. A 1/4" x 1" NPT pipe nipple and a 1/4" elbow move the sensor away enough to hook it up. This is a major PITA if you wait until the engine is installed.

Any TBI system uses the ECM to adjust the timing so the distributor is not getting moved as you don't re-time the engine @ tune ups. Expect the distributor to be seized fast. Remove the hold down and soak it with a lot of penetrating oil, like CRC 5-56, overnight or longer, re-applying the oil. You will be able to remove it by hand.

Always replace the oil seal 'O' ring on the distributor shaft. The one from GM is under $2.00 and is not rubber but a special compound. The old ring is dry and brittle. It will leak oil, a lot of oil!

The rotor points to 7:00 o'clock when #1 is at TDC.
When the distributor starts to come out, the rotor will move to 6:00 o'clock position. When you install it; start with the rotor pointing to 6:00 o'clock and is should swing over to 7 o o'clock. The new 'O' ring will make it snug, work at it till it is completely seated. Make sure that the engine is on compression and the timing marks are lined up at zero. If it won't start, line the marks up and take off the cap. If the rotor is pointing at 2:00 o'clock; you were 180 degrees out, do it over.

Camaro flywheels are thicker than S-10 flywheels so you can't use a Camaro flywheel in the 2.8 bell housing 'cause there is no room for the fork. The 5-speed swapper w/ 82 thru 87 needs to obtain a neutral balance flywheel from an 88-93 2.8 S-10 -or- have a machine shop remove the weights & neutral balance their flywheels W/ a flywheel resurface this would be as good as buying a new flywheel.


DOIN' THE SWAP:

The 4X2 is an easier swap because the extra parts for the 4X4 are in the way. It is possible to remove the engine & 5-speed together from a 4X2 if you are careful. Raise the back of the truck & use the biggest jack stands you can beg or borrow to hold it up. Mark the driveshaft & remove it from the differential. While doing this, remove the trans drain plug & drain the trans oil. Remove the center bearing [if equipped] and the trans cross member. NOTE: the center bearing bolts are 18mm which is a size most metric wrench & socket sets omit! You might want to replace them when it goes back together. Once the driveshaft is out of the way; unhook the speedometer cable, the reverse light wire [it has a clip on one of the top trans bolts] and unbolt the slave cylinder from the bell housing and move it to the side. Everything from the bell housing back should be clear. Go in the cab & remove the shifter, unscrew the boot & slide it up, pull out the foam sound isolator [save this!] and remove the bolts holding the shifter in place {make sure the trans is in neutral} and pull the shifter up & out of the trans. Now you are ready to go under the hood.

Wow, looks crowded in there!

Remove the battery, drain the radiator, remove the shroud, unhook the hoses from the radiator & remove it and the lower shroud. Remove the bolts holding the clutch fan to the water pump shaft and remove the fan. Start removing the belt driven items. Remember to keep the power steering pump upright & slide it into the corner behind the driver's headlight, the hoses should allow this but it will leak if it is not upright. Hopefully the A/C compressor can be moved to the passenger side and stay connected [the author's truck did not have air] and all the rest of the accessories & the mounting brackets get removed from the engine compartment. This is a good time to unhook & remove the fuel line and return line from the TBI [watch out for fuel under pressure] and the fuel filter. This makes a lot of space in front of the engine where one can stand, after climbing over the radiator support, and work on the engine. Use lots of penetrating oil on the exhaust manifold bolts, start applying it a few days before you want to start removing them. The exhaust manifold & 'Y' pipe can stay in the truck. Remove the bolts connecting the manifolds to the engine.

Remember that it really helps to take pictures of the general layout of the engine compartment before tearing things out and it is the only way to remember the location of the items that share the manifold bolts!

Remove the air filter assembly and note the vacuum hose connections. The next step is to remove the intake manifold. The TBI can be left on the manifold if you have an old 1/2" offset wrench, the kind where the opening is dropped below the plane of the wrench handle, to loosen the two middle fasteners blocked by the TBI body. After removing the manifold fasteners, take (2) of the nuts & jam them on the stud right in front of the distributor & remove the stud. This allows you to remove the TBI manifold b/4 removing the distributor [makes room to soak the distributor & work it around] remove the distributor. The hex shaft that drives the oil pump might come out with the distributor. Remove the coil & EGR controller from the rear lift eye. This will make room to get to the grounds bolted to the back of the driver side head. You should be able to stash the top engine electrical harnesses over the wiring running behind the engine. Pull the bottom harness back after unhooking the knock sensor & the starter wires. Unhook the oil pressure sending unit(s) & unscrew them from the oil filter mount. Set up a chain & your hoist, you should be ready to remove the engine mount through bolts. Double check that everything is disconnected and tighten up the hoist and make sure it starts to lift the engine. Triple check that everything is loose and start lifting. Work the exhaust manifolds around the oil filter & mount & the starter until the engine is free [the spring loaded bolts to the 'Y' pipe alow them to move around a bit]. We had to lift the crank pulley over the radiator support before lifting the engine & transmission clear. If you failed to drain the trans earlier, you just made a big mess!

A re-installation tip:

When installing the transmission & engine you will reach a point where the upper engine mounts are sitting on the front half of the lower mount and it seems that it won't go any farther. Get a jack under the transmission tail shaft area & jack the transmission up against the floor boards. This will raise the back of the engine and allow it to be lowered over the bottom mounts.

Final Thoughts:

Working alone, the author spent almost thirty hours, working nights after work [used a bay in the shop @ work] and one weekend to complete the swap. One shop mechanic helped for around 15 min. and had the idea to raise the transmission to get it to fit. A forklift was used to do the lifting and the shop parts washer allowed each part to be cleaned after it was removed. Groups of parts & their fasteners were stored in big zip loc bags & piled inside the cap covered bed. The crate engine was kept inside its bag until ready to dress w/ the parts off the 2.8. It is easy to change the clutch when the transmission & engine are sitting on a skid!

The crate comes with a cardstock covering the intake area. This was removed and a bunch of clean rags covered this area and the cardboard was placed over the rags. The intake was installed after the engine was back in the truck and the distributor waited until the engine was filled with oil and the oil system was primed. You cannot use a wimpy drill to prime the system as the building pressure results in the need for a lot of torque to keep the oil pump turning. Make dams out of rags to keep the oil from spilling all over and prime the system until oil comes out of ALL the pushrods, the last few will take some time to get oil.


This info was all based on personal experience installing a HT 3.4l crate engine into a 1988 Tahoe, small cab/long bed 4x2 truck with a 5 speed transmission. The decision to pull engine & transmission together was based on the author's previous experience changing a clutch. The top two bell housing to engine bolts are almost impossible to remove and the T-5 seemed more compact than an automatic so it seemed possible. Tractor trailer jack stands were used under the rear axle and the front air dam was almost on the ground. This might not be achievable by many people that don't have a level concrete floor & huge jack stands to work with. One alternative would be to strip off the intake & both heads. One person used to say you could then straddle the engine block and get at those two top bolts.


4X4 complicates things although some guys have reported that the engine, transmission & transfer case will come out together if you disassemble the front suspension enough to make room to clear the front differential. If this is used on the website, someone familiar with a 4X4 swap should add directions suited to the four wheel drive models.

On 4x4 models you will have to use the oil pan and oil pickup tube so that you will clear the front differential.

Writeup by Mark Wismer (AKA Wis Bang)

Last Modified: 7-13-05 JCH