BB Mileage Question?

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J

jeeper

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Hello,

I have been asking a million questions as time has gone on here trying to come up with a workable combination for my "needs"!

I have been debating between BB and SB now for a couple of months.

I was contemplating running my 440 with fenderwells in my A body along with my 4.10 rear.

Real nice for acceleration, but I probably would have to take out a loan for a summers playing.

Does anyone have any experience switching gears and a BB and what effect it had on mileage?

Say from 4.10's to 3.23's and a taller tire? I am not building a drag only car.

I know the MPG will be different, but by how much?

Thank you, ROB
 
I can't answer the question with regards to 4.10 gears, but my son's Dart GT convertible has a mild 440 (stock 1970 shortblock with a cam similar to a stock magnum grind), a-body hemi four speed, and a 3.23SG geared 8-3/4. The rear tires are 235-60-15s. When the engine had fewer miles and a good tune up we got as high as 15mpg on the highway cruising at 70-ish. The car hits triple digits way too easily, too............allegedly. We built the car to be a driver that we could take anywhere. We've never tried to run it at the drags, but I wouldn't expect anything better then 13.5s due to limited traction. It's really plenty fast and I wouldn't heistate to jump in it tomorrow and drive three or four hours to get somewhere.
 
Mileage shouldn't even be in the equation with a BB. If mileage is a factor and you still want to go fast then you need a small inch motor with a turbo. This way you have the mileage of a small motor and the punch of a BB.

Chuck
 
My 71 Road Runner was getting 15mpg on the highway with a 383 4spd, 509 cam, 3:23 rear, Pulling an overloadded 6'x12' U-haul trailer from NY to Indy.
Had fun on that trip. I was alone in the car and the wife was driving an 81 Caviler.
She would go like crazy down one hill, and I would pass her going up the next one. Road runner would just cruse up the hill like there was no trailer behind it.
 
My issue is just distances. I do go up to Washington and would like to run at Renegade etc. but it would be nice to get there first.

I was just curious as to what people's responses are. I went from having about 75% of a hot small block or two in early september to adding two BB's and headers etc. to install them by now.

I want to make sure that my car does what I need it to.

Thanks for the replies, they do help with my decisions.

ROB
 
On the dodgecharger site they mostly have BB and with gas prices so high it was talk about alot. I seen most were saying 7-8 MPG, now thats with holley's and big cams. The eddy's carb's and stock carters carbs. get better. Not sure if a small block is always much better. My 318 with a holley HP 750 carb and 3.91 gears gets 10-11 MPG. I had a mostly stock, expect dual exhaust 318 in a 1977 Grand Fury and I was getting 16 MPG on the freeway back in the 55 mph days.

BTW back in 1972 Nixon's limo got no more than 4 MPG.
 
I had about 2 mpg gain going from a 3.91 to a 3.23 gear with a 235/60/15 tire with a small block. you will probably get right around there in difference or maybe a little better going from a 4.10 to a 3.23. I don't even want to speculate what kind of overall economy you will get in the end. I got about 9 mpg with the small block and 3.23. I couldn't ever keep my foot out of it.
 
If I keep my foot out of it, I can get about 8 mpg with my 440-6 ,4spd., 3.91. Even with a 3.23 the car would consume a lot of gas with it`s large displacement, cam,valves,etc. It`s very hard to reach a compromise between performance and gas mileage. I believe you should build it one way or the other. My friends Hemi Ram only gets about 12 mpg so my 8 is not so bad after all. Lol!
 
jeeper said:
My issue is just distances. I do go up to Washington and would like to run at Renegade etc. but it would be nice to get there first.

I was just curious as to what people's responses are. I went from having about 75% of a hot small block or two in early september to adding two BB's and headers etc. to install them by now.

I want to make sure that my car does what I need it to.

Thanks for the replies, they do help with my decisions.

ROB
Click to expand...

Wow that would be a drive for you. That's the track I run at. You aren't to far from Champion are you?

Dollars to dollars it is probably less $ to run a BB than having to spend the added $ on making a good turbo motor. It won't cost you anything to park the BB for awhile until you get the $ to pay for fuel. But you have to invest the $ up front to purchase the turbo setup and hardware.

So with the BB it is a pay if you want (or can afford) to play. That's exactly what happened to me this year. I couldn't afford the cost of fueling the motorhome and expenses to race this year in the Summit Series so I didn't. I still have my race car and it didn't cost be anything to let it have the year off.

Chuck
 
Depending on the set up of the motor - I would run a carter 4bbl preferably a TQ or at least an AVS, they do a better job of metering fuel than holleys do, for off idle part throttle etc. Lots of folks dont like TQ's - I do, never had any issues with them. Run the 323 gear, if your car is an Abody it will have plenty of juice in mild form with a 440 BB or whatever. I'd guess properly tuned a mild 440 with a TQ, and 323s should get 14-16 mpg. Put short slicks on it for racing, this effectively increases your axle ratio.
 
As far as small block fuel mileage, my absolutely stock 340 gets no better mileage than my son's 440. The difference is that the 340 is backed by a 727 and the 440 car has the aforementioned four speed. Both cars have 3.23 gears.
 
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