STS Scott Posted April 19, 2004 Report Share Posted April 19, 2004 Our family has owned both our Aurora and STS for about 4 years now (the STS is a 95, the Aurora a 97), and they are still going strong. However, it is interesting how differently their powertrains perform, being so closely linked in design. In fact, the 4.6 Northstar in the STS is very rough and raspy relative to the 4.0 litre Olds engine. How can this be? I realize the only outstanding difference in the motors is the displacement, but that wouldn't be a factor in their smoothness, right? The Olds at start up is smooth as silk, but the STS has a distinctive "jerk" (like you can feel the engine jolting), and then comes down to a relatively smooth idle (but not as smooth as the Aurora). Could this be a sign of a problem, with the balance or something like that, in the STS engine? Thanks for any insight! " ...'took my Cobra down t' the track, hitched to the back o' my Cadillac..." - Jan & Dean, 'hey little cobra' Scott Link to comment Share on other sites More sharing options...
Ranger Posted April 19, 2004 Report Share Posted April 19, 2004 You must have a problem of some sort. My Northstar is as smooth as a prom queens thigh. Link to comment Share on other sites More sharing options...
Scotty Posted April 19, 2004 Report Share Posted April 19, 2004 My guess is that the camshaft in the cadillac is a little more radical causing the 'rough' idle that you describe, the engine is loping.... Have you ever seen and heard the distinctive lope of a 3/4 race cam, not a smooth idle at all, some of the newer NS's are even rougher if my memory recalls from prior posts. Thats my guess, lets see what Guru has to say. One HP+ per Cu. In. does not come without some earthshaking! You should have seen my 427/435 (six pack) 68 Corvette! Mike Link to comment Share on other sites More sharing options...
Randy_W Posted April 19, 2004 Report Share Posted April 19, 2004 Mine idles so smoothly, I tried to startit with the engine running a couple of times! Link to comment Share on other sites More sharing options...
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