I asked this question inside another post but it kinda got lost amid other discussion. I used to have an 85 2.8 firebird and now have an 89 firebird. I noticed that the 85 has a smaller oil filter than the 89. Also when looking though the walmart book on spark plugs it showed 82-84 (carb) 2.8 had a different spark plug than the 85-88 (fuel injected) which that is understandable between the carb in fuel injected but what I found to be interesting was that the 89 uses a differnt spark plug than the 85-88 .... it actuall uses the same one as the 82-84 carb. Does anyone know why? That doenst make sence since they should be pretty much the same motor in 85-88 as it was in 89. I understand that in 87 they beefed up the bottom end of the 2.8 ... is that why they put the bigger oil filter? Just kinda curios about this ... especially on the spark plugs

 

The 2.8 V6 engines produced from 1985 to 1989 as used in the Firebird /Camaro are the same. All use the high performance cast iron heads which incorporate the fast burn combustion chambers, the 67mm valve openings, the more aggressive cam, HD nodular cast iron crankshaft, larger mains, higher compression pistons, one piece neoprene crankshaft seals, electronic multiport fuel injection, and a host of other upgrades over the 1982-84 2.8's, which were themselves durable engines. The changes to the V6 done in 1987 and known as "generation II", (aluminum heads and an internally balanced crank) were for the front wheel drive applications, i.e. Beretta, Corsica, Celebrity, 6000, etc. As far as the oil filter differences, the 1985 V6 cars F-cars came from the factory with an AC PF47 oil filter. By the late 80's the longer PF51, and then the PF52, ( a better version of the same filter was specified). The advantage of the longer filter is that it provides a large filter area, traps more dirt, and hold more oil, in this case half a quart more. Four and a half quarts are needed to fill the crankcase with this filter, which means more oil for lubrication, cooling, and greated dilution of contaminates. The 1985 and later cars can all take the longer oil filter. I think TomP has mentioned this numerous times, and in his major tune-up post.

 

ok thanks... my 85 took the shorter filter though so I guess they didnt put the longer filter until 86 but what about the spark plugs? What are the 89 2.8 use different plugs from all the other 2.8L fuel injection (85-88) if they are all the same motor and use the same plugs as the 82-84 carb motors. Did the figue out after a few years that is what they shough have used all along? So should 85-88 2.8 ownwers change their plugs out to be the same as the 89's .... and owners of the cars with the shorter oil filters upgrade to the longer ones?