my 1991 5 speed tbi camaro runs 3000 rpms at 70 in 5th gear is this right or should it be lower??The gears are stock i think at 3.08

 

it'd help if you knew for sure what the gears are and not what you think they are. 1:1 with 3:08 would put you around 3000.

edit: don't expect much from the factory installed tach. they're not known for being accurate.

 

Don't believe your tach. When I'm going 70 my tach reads ~2300-2400. With my gears, it should be around 1700-1800. Well, I hooked up my laptop to the ALDL on the car, and geuss what. I am doing about 1700-1800 at 70. My tach is off .

 

My automatic TPI with 3.23's out back runs at 2500rpms at 75mph. Your at 3000 rpms at 70mph? I thought the 5 speed would be better for highway driving? -Nick.

 

First, either your tach is off, your speedo is off, or you've got a 4.11 rear gear.

My 'Bird has the relatively rare 0.61:1 top gear in the T-5, and 3.08 rear gears. With 245/50-VR16 tires, it runs an actual 1820 rpm at 70 mph. My tach reads about 1920.

If you have the more common 0.74:1 rear gear with 3.08's, your engine speed should be about 2200 at 70 mph.

By the way, it's rare for a tach and speedo to be spot-on, unless you paid some bucks to have them calibrated.

If your speedo and tach are relatively accurate, then the math says you've got a 4.11 rear gear with the common 0.74 top gear. That may be too much of a coincidence.

Don't trust the markings on your rear axle. Manually check your rear gearing. You can do it without tearing anything apart.

1. Raise one rear wheel off the ground.
2. Block the front wheels so it won't roll, and use a jack stand. Safety first!
3. Put the trans in neutral.
4. Try to turn the wheel that's off the ground. If it won't turn, you either have the park brake set (be sure it's off), or you have a posi. If you have a posi, you'll need to raise the other rear wheel.
5. Take a piece of chalk or a marker and put a mark on the inner sidewall of the tire so you can watch its position.
6. Put a mark on the driveshaft so you can see its position.
7. Rotate the driveshaft and count how many turns it takes to rotate the wheel exactly one turn.

2-3/4 turns = 2.73:1 rear ratio
Just under 3 = 2.93
Just over 3 = 3.08
3-1/4 = 3.23
Just under 3-1/2 = 3.45
3-3/4 = 3.73
Just over 4 = 4.11

This will tell you whether your instrumentation is off, or if you've got a different rear ratio than you think.