Updating the GM 2.0L Engine: rebuilder's guide - Second Generation Forum - j-body.org

Updating the GM 2.0L Engine: rebuilder's guide - Second Generation Forum

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Updating the GM 2.0L Engine: rebuilder's guide

Sunday, December 09, 2007 8:06 AM

i thought this might be useful to someone here.

taken from http://www.engine-builder.com/

Quote:

Back when GM introduced the "J" cars in 1982, the original 1.8L pushrod motor was not very exciting. Chevy quickly upgraded it to a 2.0L for the Cavalier, but the other divisions (Buick, Olds and Pontiac) had already found something better. They imported the Brazilian-made 1.8L OHC engine that was originally designed for the German Opel and used it in their "J" cars.

There were both turbo and non-turbo versions used from 1982 through ‘86. Then, in 1987 the engine was bored and stroked to make it into a 2.0L. Both turbo and non-turbo versions were used through 1991, but only a non-turbo engine was offered from 1992 through 1994.

Although all the 2.0Ls are basically the same, there are some subtle differences that can cause problems for the rebuilder who doesn’t know what to look for. Here’s a closer look at the latest versions in this family of engines:

BLOCKS
1987-’91: All of these blocks have the same casting number (90209802) even though there are two versions — one with a six-bolt bellhousing for the automatic transmission, and one with a seven-bolt housing for the manual transmission.

Note: The seven-bolt block can be used with an automatic, but the six-bolt can’t be used with a stick.

All these engines have a hole drilled in the left side, toward the front of the block, just above the pan rail, with a long, brass cup plug that sticks into the crankcase. It’s used for a sensor that picks up a signal from the two steel pins in the front counter weight and indexes the computer for the sequential fuel injection that’s used on the turbo motors.

1992-’94: This block is the same as the earlier one and will have either the old casting number (90209802) or a new one (90400045). There are two differences, though, beginning in ‘92:

•The hole for the brass plug wasn’t needed in ‘92, so it’s no longer drilled. See photo.

•There is a boss on the left side toward the front of the block, and about half way up on the side is drilled all the way into the crankcase with a small, threaded hole beside it. Although the boss has always been there, it wasn’t drilled until ‘92. It’s needed for an additional sensor that provides data to the computer for both the direct ignition (DIS) and the sequential fuel injection (SEFI). See photo.

CRANKS
1987-’91: The early crank had either a 9028036 or a 90280399 casting number. There are two steel pins sticking out from the front counterweight that are used to index the computer for SEFI on the turbos, but they aren’t needed for the naturally-aspirated engines. See photo.

1992-’94: The crank was changed in ‘92 to accommodate a reluctor wheel. The face of the front counter weight was machined, and three countersunk holes were drilled and tapped so the wheel could be bolted onto the crank. See photo. If the reluctor wheel is damaged in any way, it must be replaced with a new one from GM (p/n 90265094) at a cost of about $40.

RODS
All the rods are interchangeable in sets. There aren’t any casting numbers, but there is one hump on the early (1987-’91) rod and two humps on the later (‘92-’94) ones. There is a slight difference in weight, but GM lists only one replacement rod for all the 2.0Ls, so it’s safe to use them in sets, and it should even be okay to use them interchangeably.

HEADS
1987-’91: The original 2.0L head had a 90209851 casting number. It has a "modified, heart-shaped chamber."

1992-’94: The late model 2.0L head has more of an oblong, "D" shaped chamber that increased the compression ratio while improving quench and squish when used with the revised piston. There are two castings; the engines originally came with a 90400095, but the replacement head is a 90209896.

The later service head has a large, threaded boss surrounding each spark plug, probably for a threaded heat shield that is used to protect the plug wires in some other application. The threads aren’t needed for domestic engines, but they don’t create problems either, so GM uses this fits-all head for service parts.

CAMS
1987-’91: The 2.0L originally came with two different cams. The naturally aspirated engines used a p/n 94658951 with a 179°/192° duration. The turbo motors used a p/n 94658949 that had a 189°/189° duration.

1992-’94: The late 2.0L was available only as a naturally aspirated engine, but it used the "turbo" cam, p/n 94658949 (which is a Wolverine CS866 or a Melling SPC-19), along with the higher compression ratio to improve performance.

PISTONS
1987-’91: The original piston had a dished top, just like the 231 Buick. It was made by Metal Leve. See photo.

1992-’94: The late piston has a smaller diameter cup that is offset to one side so it lines up with the combustion chamber. It has a Metal Leve casting number (90500879) on the inside of the skirt. Using the early piston in the late engineor the late one in the early engine will cause problems.

RINGS
Both the early and late 2.0L engines share a common ring set with a 1.50 mm top ring, a 1.50 mm second ring and a 3.0 mm oil ring.

OIL PUMPS
All 2.0L engines share a common oil pump, but it’s not the same one that was used on the l.8L; it’s a GM p/n 94657310.

FRONT COVERS
GM has used three different front covers for the timing belt, including one that was carried over from the 1.8L that is not shown in the GM parts book.

•Some of the early 1987 engines used the carryover 1.8L design with the one-piece plastic cover that bolted on and covered up the front of the engine.

•All late ‘87s and all ‘88s used a four-piece plastic cover that enclosed the belt. Two of these pieces have to be installed before the timing belt goes on, so the rebuilder has to put them on the long block. They are available from GM as p/n 90264873 and 90281810.

•The latest version was used from ‘89 through ‘94. It has a metal backing plate that goes on the engine before the gears and belt are installed. Then, a one-piece plastic cover is installed over the belt. The backing plate is p/n 10068587.

REBUILDING TIPS
•The 2.0L heads don’t seem to crack nearly as often as the 1.8L heads did, but it’s still wise to inspect them carefully, especially between the seats. The valve stems are 7.0 mm, so it takes special tooling to do the guides.

•The pistons are fitted very tightly in the bore. The OEM specification calls for .0004" to .0012" on the naturally aspirated engine and a little more on the turbo. The pistons have a very short skirt, so they will rattle if they have too much clearance. Be sure to doublecheck the clearance required for the pistons you buy and stay within the specified tolerances to avoid noise problems.

•Use new cams for all these engines for three very important reasons:

1) These cams are very difficult to clean because it’s almost impossible to remove the hardened steel balls from the oil passage that is drilled through the center of the cam.

2) These cams have an involute on the flank that is hard to duplicate with many cam grinders. If it’s not right, the lifters will pump up and hold the valves open.

3) These engines tend to be hard on cams during the initial start-up. Most aftermarket cams are made of a better material to help solve this problem, so buying a new cam is cheap insurance on a comeback.

CONCLUSION
That’s the story of the GM 2.0L engine family. As you can see, it’s pretty straightforward as long as you build the right combination, watch the piston clearance and use a new camshaft. There are lots of "J" cars still out there, so plan on rebuilding a few in the years to come. The rebuild time versus profit margin makes these engines a fairly good proposition.