The Stovebolt Site Forums The Shop Area The HiPo Shop 4/11 rear end?????/

I have a 4/11 rear end from an 87 s10 blazer, will this ratio work well in my 40 1/2 ton. I am installing a 350 chevy with an automatic tranny. I have read this ratio is to low , your thoughts. Thanks...

It all depends on what tranny you are going to use.If you are gonna use a 350 or 400 tranny it will be geared to low for good MPG.However that 4:11 would work out real nice behind a 700R4 OD tranny.The OD makes all the difference in the world for decent MPG.I am running a 700R4 with a stock 3:90 in my 55,it gets 20 MPG,and performs nicely with that wicked low gear.

Might work ok behind a 700r4. It all depends how you want to use your truck.

I have selected 4.11 gears for my 1940 gmc. I will be running a 302 gmc 6 cylinder and a 5 speed overdrive transmission. With 30 inch tall tires, my truck will do 70mph at 2200rpm.

Without knowing your goals, there is no way to make a reccomendation on gearing. Will you be racing? cruising? hauling? etc.

By the way, there isn't a law that requires folks to put a 350 with an automatic transmission in these trucks. A nearly stock restoration is way cooler than a mismatched chopped hotrod IMHO. Prewar trucks are really rare. This is your truck, you pay the bills and you make the decisions. Just make sure you research so you are happy with the end result. The parts you remove from your truck may also help another truck live.

Thanks for the info.. I intend to cruse with this truck. I would like to move along on the open highway yet have some get up and go on take off. Have not selected a tranmission yet.What type vehicles would the700r4 be found in.

i have a 350 with the 350th tranny in my 46 and it originally had a 4:11 in it. I changed to a 3:26 and changed it out again in favor of a 2:73 and it cruises along just fine at about 2000-2100 rpm. No problem with getting off the line either.

mike

sounds like the 4/11 may be on the outs..I bought a junk blazer to use the steering ,pedals ,booster etc, hoping the rear would work with my plan.. guess i will look for a 2/73..What radiator did you go with?

I'm running a 327 with TH350 trans & 355 gears. Lots of go, but at 55 mph RPM around 2,400. 411 gears would be tough on gas & ears at highway speeds. I think you can get an OD 350 ( Gear Vendors ) but kinda expensive.

i went with an aluminum radiator made by PRC. Look for it at Rutters Rod Shop. Price is $410. Runs nice and cool. Even with the 2:73 rear the fuel mileage is only about 15mph. Can not get it much better than that.

Mike

I run 3:73 gears with a 700R4 tranny, 350. We get close to 20 MPG on the highway, RPM's less than 2000 at 55 MPH. I ran 3:73 gear in our Nova with a 350/350 RPM's were 2500 on the highway, got 10 MPG

As with anything else there is a happy medium to gearing.First of all I was lucky to find my 700R4,a freind of mine built it for racing,and he decided later that he would rather have a 4 speed manual tranny. I just happend to have a 4 speed M22 in my pickup at the time,so we just traded trannies.So here we go,as far as running tall gears to improve mileage there is a limit.Which even with a turbo 350 or 400 seems to be about 3:08. To my way of thinkling,anything taller than that for instance a 2:73 is a bit much. You reach a point where even cruising at road speed you are laboring your engine quite a bit just to maintain a decent speed.Hence the 15 MPG with 2:73 gears.If ya wanna do some math heres how an OD trans helps you out,even with 4:11 gears. A 350 or 400 Turbo,or a standard 3 or 4 speed has a ratio of 1 to 1 going to the final drive,(rearend) whereas a 700R4 runs around .78 to 1 ratio to the rear.Same way with any OD trans. The numbers might fluctuate a little but they are all in the same ballpark.Like I posted before my 55 has a healthy 350 smallblock hooked to a 700R4 then into the stock 3:90 rear. Plenty of performance and 20 MPG all day long.Most of the guys I know who are running a 350 or 400 Turbo auto are running 3:08 gears,which seems to be about the limit.I am pretty sure my 700R4 came out of a 1984 Chevy.One other thing on the 700R4,the first gear is very low,I can bark my rear tires any old time with that setup,and if I hold er down she will bark again going into 2nd and 3rd gear.

My 250 will get in the range of 18 to 19 mpg at 55 mph, jump up to 70 or 75 and it drops to 14 or less. With a T350, 3.08 gear, and 28" tires, its running pretty low rpm, but low rpm is not always better fuel mileage. You need a lot of low rpm horsepower and torque to pull a low gear. My wifes VW 1.8 liter runs 70 mph at 3200 and gets 30 mpg, so its all in the tune up and design of the whole package not just the rpm. Joe