Like I said, I just put a 350 trans into my car, switching over from a crappy 700, and i know that a lot of guys use 350 trans' in their cars, and well, I was driving down the highway at like 85 MPH, and doin just under 5G! So, for all you guys out there that are running 350's... how do you manage to run such high rpm's on the highway?? BTW, i'm runnin 3.23 rear. Just wanna know if any of you have any suggestions... Thx

 

This is the closest scenario if the Turbo 350 isn't going into 3rd.
However, this was with 29.5" wheels???


RPM 1st 2nd 3rd
1000 10 17 26
1500 16 26 39
2000 21 34 52
2500 26 43 65
3000 31 51 78
3500 36 60 91
4000 41 69 104
4500 47 77 117
5000 52 86 130
5500 57 94 143
6000 62 103 157
6500 67 112 170
7000 72 120 183

Believe you-me, there's something wrong. Weather your tach is messed up or you’re not going into 3rd...

With an average 26" wheel, you would only be doing about 3600-3700rpms in thrid @85mph.

Ron

 

My suggestion would be, fix your tach. It's way off, which is very common in these cars, and they always seem to read high when they break. With 3.23 gears, you should be at around 4000 at that speed.

Lots of cars came just like that for decades. I have had I can't even tell you how may cars with a 350; I still have one eith a 350, and one (a 74 Caprice convertible witha 454) with a 400 and 3.42 gears. Lots and lots of cars came from the factory woth 350s and aven higher gear ratios; 70s Z28s for example had 3.73 gears. I had a 79 Z28 with a 4-speed, same high gear situation, and 4.10s; it was a road car alot of the time, I lived in Memphis then, I can recall going to Indianapolis, Atlanta, and a whole bunch of other medium-length road trips like that, without a problem.

The way you manage to run such high RPMS on the highway, is by using the gas pedal. It's really quite easy. You'll get used to it.

 

Verify that the shifter is putting the transmission into "Drive".
As ronterry said, it is probably in second gear or transmission can't upshift to "Drive" for some reason. Transmission should make two distinct shifts from "First" to "Drive".

 

Id check to see if your speedometer is correct. You should be around 3K/3200rpm at 75MPH like ronterry pointed out.

 

Well, the speedo isn't hooked up, but I know just by the feel (and how fast I was passing other cars) that I was doing about 80-85 MPH and I was at exactly 4700 RPMs. And I know the trans is going into 3'rd, cuz it has a transgo shiftkit in it, and I can distinctly feel both shifts from first to second and second to third. I dunno, maybe my tach's off.... but it's really bothering me. I don't konw how to find out if the tach has gone bad or not though, and plus, even if it has, i don't konw why it would have. Anything else anyone can point out I might be missing??

 

Well does your car SOUND like it's actually at 4700 rpm. In my car at least I can hear a distinct difference in exhaust tone between 4000 and 4700 rpm.

 

Yeah, it sounds like it's pretty damn near 4500 RPM's or so. A friend of mine has a volt meter which can check RPM's, so i'm going to use that tomorrow and compare it to what the tach is reading. Anyone else ahev any ideas?? But even still, at 3500 RPM's down the highway, how do u guys manage on gas???

 

I dident manage. When I had the 3.73's in the Camaro and a TH350 I couldent deal with it. I dont remember what size tires I had at the time but they were 15in rims and the Autometer tach read 3800rpm@ 75MPH. The 3.42's droped it down to a reasonable 3000rpm, but I also went to a larger diameter tire.

 

Finally got er in huh? Something don't sound right to me either, hell I got 3.42's and when I go through the traps in the 1/4 it's only 45-4600 at 97-98 mph.
With the 3.23 it should be okay for mileage on the hwy, plus now it should be one hell of a racer from a roller.

 

Yeah, well like I said, i'm gonna check the tach tomorrow and see if it's right or not... but come to think of it... I may have gotten so used to driving my mom's sebring convertible, that being back in my car, I could have possibly been doind 103 MPH in my car, and it just felt slower from being in that other damn slow car. Oh well, but I was thinking, how much inpact would the torque converter play in all this?? I mean, it's only a TCI 2000-2200 stall, but still, how much would that affect highway driving??

 

<b>But even still, at 3500 RPM's down the highway, how do u guys manage on gas???
</b>
My car:
TH350 Stall: 2400
2.77 Gear
355 sbc. powerband 2500-6500
Highway Economy: 14 MPG~
City: 12 MPG~
this is with driving it EASY. Under full throttle in first gear I top out at 65 MPH~ before I even hit second. I can drain both front and back fuel bowls of my carb at about 35~MPH during that run, if the fuel pump isnt on. (to give you an idea of how much fuel I actually use at WOT)

My GEAR is the only thing holding me back. the 2.77's obviouselly do NOT match the rest of the car.
Solution:
A Smaller Camshaft
B Gear Change
If I do option B then I will lose ALL HIGHWAY economy... Thus option B is also: Buy 700R4 for car.
This is an expensive option but necessary to maintain Daily Driver Status and have proper Gearing (4.11) for the engine.

As you can see, its a catch 22. If you go for gearing, you lose economy fast without overdrive. If you stick to resonable torque camshaft profiles, you lose horsepower and E/T. Solution is money, always has been.

Im swapping out my TH350/2400 Stall for a 700R4 real soon, after my gear change. The TH350 is a Great Tranny, but not in my opinion for daily driving. Im also adding EFi and a blower. this ought to liven things up.