RPM's
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Joined: Oct 2007
Posts: 87
Likes: 1
From: Davenport Iowa
RPM's
I have a stock L-48 75 went for a drive today and noticed that at 55-58 mph the tach read 3700-3800 rpm is this about right for 308 gears and a th400. I drove on the interstate last year at a steady 65 to 75 and seem okay but I hadn't fixed my tach yet so I don't now what the rpm's are at those speeds. Don't know why I didn't try higher speed but it seem like it was kind of tight for only 55mph.
Thread Starter
Advanced
Joined: Oct 2007
Posts: 87
Likes: 1
From: Davenport Iowa
I have had trouble with the shifter going into second when I thouht it was in drive and have had to push it up like a half a click to get into drive. If it's not raining tomarrow I'll take it for a spin and check it out. By the way is there a fix to the shifter problem I'm having.
Pro
Joined: Jun 2007
Posts: 634
Likes: 0
From: Hastings MN
No way that's right. Way, way high.
2nd gear is 1.48, right? Stock tires, 3.08 rear, and 1.48 transmission gives you 3243rpm @ 58mph. You sure you have 3.08? Same setup with 3.73 rear gears gives 3928rpm @ 58mph.
2nd gear is 1.48, right? Stock tires, 3.08 rear, and 1.48 transmission gives you 3243rpm @ 58mph. You sure you have 3.08? Same setup with 3.73 rear gears gives 3928rpm @ 58mph.
Pro
Joined: Apr 2007
Posts: 736
Likes: 1
From: Chester VA
That will vary with tire size, also does that account for trans slip which would occur since it's not a lockup trans? Definitely sounds like you're in 2nd, with 3.08's and 255/60's I'm at about 2200 at 60 if I remember right.
Melting Slicks
Joined: Jul 2005
Posts: 2,545
Likes: 3
From: 406ci SB, AFR 180 Heads - 490 HP @5,600 RPM 529 lb-ft @ 4,100 RPM
I agree with the above answers, way too high for 3.08 gears. Our 79 has 4.56 gears, and turns about 3600 rpm around 70 mph with a automatic.
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