I just had my transmission rebuilt and a new stall convertor installed. The transmission was a redone by a local shop with a kit purchased from Pro-Built Automatics along withe a Edge TQ convertor using a 3K stall. My car still has the standard factory rear that came with the '91 Camaro RS's and the 2.73 gear. After the rebuild and TQ install it seems the car runs higher RPM's. Now just FYI, I'm NOT using the factory tach. I have a after market tach doing the readings. Anyways, here's what I'm reading:

50 mph - 1850
55 mph - 1950
60 mph - 2100
65 mph - 2200
70 mph - 2300
80 mph - 2450

Do these seem right for a 2.73 rear end? I don't recall them reading this high prior to the rebuild. Should this be expected from a Pro-Built Automatic kit and Edge convertor?

 

Is the torque converter locking up?

 

I'm not sure, Really don't know much about them. How would I know?

 

3000 stall and 2.73 is a bad combination. If your rpms are that low at highway speeds then the converter is slipping below the rated stall speed. Although it will still work, this slippage creates a lot of heat in the transmission and will greatly shorten it's life.

You would be better off with some gears in the mid 3.xx range. It will allow the engine to get into the higher rpms where the converter will be above the stall speed.

The rated stall speed is only an estimate, what it actually stalls at depends on how much torque is put into it. The required stall speed is based on the cam grind. The stall speed for a street/strip car should be about 500 rpms into the cams powerband. If your camshaft has a powerband that starts at 1800 rpm then you don't want a converter that stalls higher than 2300 etc.

Unfortunately, it's far too easy to mismatch parts and expect good results. You want highway gears for economy but want a higher stall converter for performance. I'd say 2100 rpm at 60 mph is very good for what you're trying to do. If you want lower rpms on the highway, put a lower stall converter back into the car.

My 454SS truck has a 4L80E transmission, lockup stock converter, 4.10 gears and 28" tall tires (all factory specs). At 60 mph, the rpm is around 2800-3000 rpm. Some 3.73 gears with the OD would really help highway cruising but stoplight to stoplight driving wouldn't be as fun.

 

I don't want 4 mpg. This car is not a strip car and will never see a dragstrip, It's used for weekend cruises. This combination is what was recommend to me by Dana at Pro-Built Automatics, That of which he came HIGHLY recommened to me by way of this forum to rebuild my transmission. So what your telling me is he sold me crap? I don't know anything about transmissions or stall convertors, This is why I relied on Pro-Built to set me up with what I needed. They where informed at the time that this is a cruise car and will never see a race track. What I wanted was to maintain good driving manners with the best fuel economy possible but still have some pop when you get on the throttle. I sent him over the full spec sheet of the 383 Stroker I had built for this car along with what the car was going to be used for. The results are what he sold me. You say the rpms' are too low? I'm actually bitching because they seem too high. I don't want to run 3K down the interstate. I was told the 2.73 would provide me with excellent highway fuel economy while the motor has enough hp to still stir up a mess if I got on it. The only thing Dana recommend with the rear was to move up a gear and no more at some point when I decided to rebuild it.

 

My truck is feeding a 454 and gets 10 in the city and around 14 on the highway. You're not going to get fantastic fuel mileage with 2.73 gears if you're using a 3000 stall converter. Since we have no idea what camshaft you're using, best guess is that you need a converter stall closer to 2000-2200 rpm to get the results you want.

Match the converter stall to the cam grind for best performance, if you're not after best performance, use a stall speed that's lower. Going higher is worse than having one that's too low. I wouldn't be surprised if you really needed a converter that stalled around 1800.

 

I'm running around 12.5 mpg average right now, most of which is highway. Yes, I would NOT consider that the fuel economy I was looking for at least as the highway is concerned. From what I'm hearing from you really tends to **** me off knowing I relied on a guy who DID NOT from what I'm gathering sell me what I was asking for and pretty much just took my $1400 and sold me whatever was lying around. Here is the cam specs since you asked.

A custom ground hydraulicrollercamshaft and roller lifters, with spec's (236/244`@.050" with .565/.585" lift on 112`LSA) are matched to Aluminum 1.6 ratio Roller rockers and 130# seat pressure valve springs.

 

What's the advertised duration of the cam? Not the @ .050"

 

You've posted some information that's applicable to a non-lockup converter and not so much to a lockup.


OP,
If the trans. is kept cool, the 3000 and 2.73 will work fine, OP. An external additional cooler would be a very good idea if you didn't add one during the rebuild / install. Some people like to run them alone, some people run them inline with the factory cooler; that's another thread. The important part is that you know your stall converter will add heat and a cooler will help keep it from destroying the trans. prematurely. A temp gauge is good too.

Lockup will help with temps. Assuming your converter is lockup, you can regularly check it by tapping the brake pedal once while cruising at steady throttle in overdrive. If the rpm rise a few hundred, then go back down to what they were initially and stay there, the lockup is working.

Yes, a 3000 stall and 2.73 are a slight compromise of parts but the short first gear of the 700-R4 means the 2.73 works fine off the line and the wide 1-2 and 2-3 drop of the 700-R4 make a stall converter more helpful than usual.

Some people love low rpm on the highway and 2.73s make them happy. Nothing wrong with the choices you made; you just won't get optimal acceleration across the board. As far as stall converters and gears go, try and drive a friend's car with different gears or converter to see if you're going to want to change parts on the next rebuild. I love my friends auto T/A w/ > 3000 stall converter but driving it let me know that I'd prefer a lower rpm converter personally. Similarly, you might find by driving another setup that you want to go 3.23 or 3.42 instead of sticking with 2.73 or 3.08.

I'm not a fan of having a huge stall, so I think I know where you're coming from and while I wouldn't choose to stay with as low a gear choice as you want, I think you chose wisely for your car.