Stall question....

[papabearxl]

So I have a 2400-2500 stall in the 87.
I have done some figuring based on the rear gear, the overdrive gearing of the 200-4R, and my tire height....I had originally figured that this setup would be great for the highway, and mpg, but I am scared thinking that I may have problems, considering the stall is higher than the cruising rpm of what I have figured (and verified by online calculator)...my thought would be I would be doing 1500 rpm at 70 mph, and I confirmed it with the online calculator at Summit Racing. (Their calculator only derives rpm for 3 speed and not overdrive, so I multiplied the rpm they derived, and multiplied by 0.67 for the overdrive gearing)
I have a 2.56:1 rear, the OD is 0.67 in the transmission, and I will be running a 27" tall tire.....
My question is, am I going to be in trouble having a 2400 stall, and trying to cruise at 1500-1600 rpm? I like to think I know a little bit about cars, but as far as changing stall speed, I am a novice....I know I can change the rear gear (and have that planned in the future), but am I going to be able to drive this thing in OD, at 1500-1600 rpm without burning something up, or will it just stay in 3rd?

Remember the motor is the 330, with the 200-4R.

 

[79malibubbctt]

It is kind of like a lock up converter. You can run at that rpm but it will be slipping inside the converter. It will stop slipping past yhe 2500 mark. Run one step above stock and you should be fine.

 

[dogsht]

If it is a factory unmodified converter it is a lock up converter (such as a GN/442/MCSS at that stall) which means it will lock up and not slip in overdrive below stall rpm once it has locked up until you smash the gas pedal which will unlock it. After your transmission has upshifted three times into overdrive and you have leveled out in speed to cruise throttle position you should feel and see a two or three hundred rpm drop on the tach if you have one once the converter locks up.

If it is an aftermarket even higher stall lock up converter it will be the same unless you don't have the lock up feature working. There are posts here about that and many online transmission vendors Jegs etc sell something to help make the lock up feature work even with a non original motor carberator etc. My GN has a rebuilt 3,000 stall lock up converter that locks up on the highway at much less than 3,000 and holds the converter locked until I hit the brake or again smash the gas. My 442 had one also but I had to modify the linkage to work with the Cadillac Q-jet as opposed to the original Olds Q-jet. This feature is not only is good for an additional 1 mpg highway and lowering the cruise rpm but also takes a lot of heat out of your transmission and cooling system making it easier for your cooling system to cool the engine.

The aftermarket also has non lock up converters for these transmissions for people who are primarily using them for a racing.

 

[papabearxl]

Thanks guys. It is a factory, lockup converter for a GN....and the transmission came with the lockup switch kit....I just didn't wanna be burning the converter or transmission up.

 

[megaladon6]

remember the stall rating is when you punch the gas from a stop. it will be fine when driving

 

[papabearxl]

Thanks for putting my mind to ease, guys.

 

[papabearxl]

I decided to contact Summit Racing Tech, for $hits and giggles, since it was their calculator I used.
This was their response to the same question I posted here:

"The converter will still be ok, but, if you need a 2400 stall converter, that tells me your cam has a cruise rpm that is higher. Now you are lugging the engine, requiring more throttle to maintain speed, and mileage gets worse. Make sense?"

 

[efigp83]

remember the stall rating is when you punch the gas from a stop. it will be fine when driving

that is correct the rpm spec on a convertor is the flash rpm that it will lock up at. I run a 10" lock up convertor in my car that has a 700r4 in it i have had it there for about 6 years and never a problem but it is pretty cool when it lobes at 25-30 mph when cruising around the neighborhood

 

[papabearxl]

I was hoping it wouldn't make my highway mpg worse, though.....I could just see it idling down the interstate....lol

If I drive it to work everday, it's about 50-55 miles round trip, and I was hoping for somewhere in the 20's for mpg.
My Sierra (6.0L) gets about 12-15 on the highway, and my 85 doesn't have overdrive, and I am lucky to get 18 with it. (It does need a basic tuneup though), so I was hoping with my gearing my mpg with the 87 would be better than both of them. I do plan on re-gearing the rearend eventually, to maybe 3.08-3.42:1, but I don't know.
I will just have to see how it does once I have it wired and plumbed, and am driving it, I guess.

 

[megaladon6]

At 60mph, my 383/200-4r/3.73 combo loafs along at about 2000rpms. Granted thats with a stock converter, but it wont really change too much. However, thats with a torque motor, if you have a 330 i assume its a high RPM motor?