If i upgrade stock 2.73 gears w/ 3.55's, with a 3 speed tranny + overdrive, will my I6 be csreaming doing 70 on the highway?

 

Should see about 30 percent increase in rpm at any given speed.

3.55 / 2.73 = 1.30

 

Assuming 29" tires you'll be running around 2350 RPM at 70. Hardly screaming, but possibly higher than you'd like with a 300. Have you considered 3.27 gears? They'll drop the revs to around 2150 RPM at 70.

 

2300-2400 would be ok at 70. A good bit lower than mine does...I wish I could do 2400 at 70...:/ I need an OD...I do about 3000-3050 at 70 if my calculator is correct. At 60 mph, I do about 2650 or so. Even that seems quite ok as far as cruising along, but naturally, I'd prefer lower. In general, it's my opinion if you have an OD, you can pretty much run any ratio rear you want, and get away with half decent highway rev's. The lower rears will give you lots more gitty-up-n-go on takeoffs. If he drops from a 3.55 to a 3.27, he'll probably loose 10-15% of his lower end torque. With mine, I got two choices for lower highway revs, a higher rear, or an OD. If I got the OD, I'd keep my 4.10 rear for low end torque. But if I don't get the OD, and stay with the T-18, I've considered changing the 4.10 to a 3.54. I could even go to a 3.33...But I worry about the effect on my low end with the 3.33. But on the other hand, considering the 300's low end torque, maybe it would be ok...Just wear out clutches a bit faster...If I could just drop my rev's at 70 to 2400, I'd feel better...I sometimes worry about a constant 3000 rpm for hours on end causing excess wear...I usually putt along at 60-65...Keeps it under 2800 or so...Makes me feel a little better..
MK

 

My 300 with 3.08 and 3 sp + OD turns 1600 at 60. OD ratio is 0.71.
If I'm towing something heavy, I stay in third gear, it's ratio is 1.00.

 

yes, i have considered getting something in between 3.55 and 2.73. I want the low end torque, but i want to get good mileage on the highway. Also, does any one know how to set a speedo for bigger tires(31"s) and different gears? Is it someething that i can do?

 

another upgrade that i am seriously considering doing is swapping the stock 1v for a holley 2v carb (http://www.holley.com/HiOctn/ProdLin...SC/0-7448.html) has anyone done this swap before, and is there any where else to get the adaptor other that cliffords?

 

Just to put info into your brain, I run a 82 100 w/1bbl, "SROD" 4 speed overdrive, 2.73 rears. I run rught about 1750/1800 @ 70 And get about 18.5 to 19 mpg on "flat" ground, 18 to 18.5 through the "hills". Passing in 4th not to bad if you have some room, but she runs out of air around 85 mph. In 3rd, she'll run around 100/105. {That's only suppoesed, I "would never" run that fast on the highway!!} Hope this little bit of info helps.

 

Yea, that's something like 1520 or so at 60 mph. That's just over idle speed!!! Cool.
Isn't it a bitch hearing those trucks pass you at 3500 rpm? Such noise!!

 

What the heck guys? I got a 4spd (no OD) and 3.08's and I'm running like 2300 at 60mph and a little under 3000 at 70mph. No fair. My 97 Grand Am GT runs 2000 at 60, but for some reason that DOHC 4 cyl. will smoke my truck in a race and use under have the gas doing it. No fair agian.