Differences and Changes Through the Years
93/94 - These engines have the knock sensor below the fire-wall side cylinder head, screwed into the side of the engine block. These engines have slots cut into the intake ports to feed exhaust gas from the EGR system into the combustion chambers. Also, the intake manifolds are cast aluminum with an internally mounted fuel rail. The harmonic balancer bolt uses a 24mm socket. Vertical ridges all the way around the outside of the cylinder walls.
95 - Same block casting as 93 & 94 with the vertical ridges down the cylinder walls. Knock sensor retained it's location from 93 & 94. EGR is now fed through the new-for-1995 thermoplastic intake manifold- the slots are no longer cut into the intake ports. A different oil pump is now used, very similar to the original style.
96 - New block casting with no vertical ridges on the outside of the cylinder walls- the walls are now smooth. Heads are a carry-over from 1995. The knock sensor is new and is positioned under the thermoplastic intake between cylinders 3 and 5, screwed into a new hole with M8x1.25 threads. The harmonic balancer bolt is now smaller (M14) and uses a 19mm socket.
97 - Carryover from 1996 although some left-hand cylinder heads in '97 had the new bolt boss for the liquid cooled alternator introduced in '98. This is identified by a new camshaft cover that has a cut-out in the lip by the lower portion of the wide (chain-case) end.
98 - New lower block casting. This new casting incorporates a new threaded hole (M10x1.25) for the new STS platform engine mount. This hole is on the lower right hand side of the engine by the corner of the timing cover. A new timing cover is now used, with a part number stamped in just above the harmonic balancer. Some very late '97 engines may have had this new bolt hole. A new bolt hole is dilled and tapped for the new-for-1998 liquid cooled alternator, just under the cam cover in the L.H. cylinder head.
99 - A very small portion of late '99 model cars got the new upgraded 2000 style block castings. Identified by a casting # in the R.H. oil passage in the block that feeds oil to the R.H cylinder head. This engine retained all internal components and cylinder heads from '98. 10.3:1 compression ratio has been retained ever since its introduction in 1993.
00 - A new engine is born. All new cylinder heads featuring static hydraulic lash-adjusters and roller followers are used. These heads feature a new combustion chamber with less valve shrouding and larger intake valves. Exhaust valves are a bit smaller, both intake and exhaust valves have longer stems. New camshaft covers are used to accomodate the increased height of the roller valvetrain. A new crankshaft with a different reluctor wheel (crank position wheel) is used, but all bearing journals retain the same dimensions. The bore remains at 93mm as its predecessors. Cast connecting rods are used as opposed to the forged ones of 93-99, and are weaker. These have been known to bend if a cylinder hydraulic locks with coolant or fuel. New completely flat-top pistons with no valve reliefs are used along with a different diameter wrist pin. The timing cover, oil pan, and flex-plate all remain the same from '99. The timing cover uses a new crankshaft front seal with an increased inside diameter. A new harmonic balancer is used and also a new right exhaust cam sprocket to accomodate the new camshfaft position sensor. The knock sensor retained the same location as the 96-99's but a new sensor is used for '00. New crankshaft position sensors are used and will not interchange with the old style. There are new EGR passages incorporated into the exhaust ports. A new coil-on-plug igniton system is used that uses two large coil cassettes that houses the four coils and ICM. These cassettes bolt into the camshaft covers and use a center-mounted spring to ground themselves to the cylinder head. A new coolant crossover has been designed with a throttle body mount cast into it. A new plastic intake is used along with a new plastic & stainless steel fuel rail and new Bosch fuel injectors. AC-Delco spark plug 41-987 is used now instead of the 41-950 from '99. The camshafts no longer are drilled through for oil flow- the oil flow to the cam journals now comes from an oil passage that runs parallel along the head. Also longer head bolts are used. The new 10.0:1 compression ratio allows for full performance on 87 octane fuel.
01- All remained the same from '00 except the engine received new exhaust manifolds with mounts for EGR tubes, that run to vacuum actuated valves (connected to the AIR injection motors). Some '00 models may have had this feature.
02- All remained the same as far as I know from '01.
03- Timing chain tensioners now use a 13mm hex socket instead of the usual 10mm.
04 - Redesigned slightly for 2004. Two new knock sensors are used under the intake manifold between cylinders 3 & 5 and on the left bank, 4 & 6. The oil filter mount now uses three bolts instead of two, and a one-piece gasket instead of two O-rings like the '93-'03 engines. New camshaft covers no longer have a hole between cyls. 4 & 6 and 3 & 5 for the coil cassette grounds. Instead, an individual coil is used for each cylinder and gets the ground from the camshaft cover itself, which is grounded to the cylinder head via a ground strap on the corner of the head. New revised pistons are used that are shorter in height around the circumference but have a "bump" in the middle". This was done to eliminate the "cold-carbon-knock" that was caused by carbon on the piston slapping the cylinder head once too much was built-up, by giving a bit more clearance between the two surfaces. Besides two, different style knock sensors, all other sensors remained the same. M11x2.0 cylinder head bolts are now used instead of the finer M11x1.5 bolts that were used from 93-onward.
A 93 and onward block & internals can be used on any car all the way up to '99 but you may have to use different heads accordingly. You can drill & tap a hole for the '96-99 style knock sensor under the intake, the boss is there on all blocks.
93 heads will work on a 94 and vice-versa with the slots in the intake ports.
95 heads will work on anything up to 99, as long as you don't need the extra bolt boss for the liquid cooled alternator. If you have the liquid cooled alternator, you will need heads from either a 98 or 99 with the extra bolt hole.
If you need to put an engine into a 98 or 99 Seville body, you HAVE to have a block that has the new style timing cover and bolt hole below it- so it has to be a '98 or '99 block (some late '97s may have had this). All of these Sevilles have the liquid cooled alternator so you pretty much need the whole engine to be a 98 or 99 because of the bolt hole in the LH head.
The Deville & Eldorado aren't as picky with the years, as they used the old style of mounting the engine in the chassis.
1993-1999 and 2000+. You CANNOT under any circumstances bolt a 2000+ engine into a 99 or older body or vice-versa. It simply does not work. Too many differences, too many sensors changed and the holes to mount them. Many people have tried, and gone through all of the work to bolt it in and realize that 1) some things don't bolt up correctly, 2) the wiring won't connect and 3) it won't run.
2000-2003 will swap without any problems at all, just make sure you have the correct exhaust manifolds for your application bolted on.
2000-2004 - any 00-03 will bolt into an 04 body, or any 04 engine will bolt into a 00-03 body but you will need to change camshaft covers, ignition coils, knock sensors (drill & tap a hole for the 2nd knock sensor for a 00-03 engine to go into a 2004 body), and keep the oil filter mount with the engine it came off of. You may need to drill and tap a hole on the L.H. cylinder head for the coil ground strap, if you're installing the 00-03 engine in the 04 body.
The coolant temperature sensor, water pump, head gaskets, and oil pan remained the same across all of these years, along with most timing components, timing chains, intermediate sprocket, etc. Various internal parts changed throughout the years- I will compile a list someday of casting #s and internal parts interchange on my website (www.northstarperformance.com) to make swaps and builds easier.
rear-wheel-drive and front-wheel-drive Northstars will simply not interchange, many, many differences there.
More information will be added as it becomes available to us for the newer model Northstars, please check back every so often!