455 '71 rivi turned daily driver?

**twoprongcrown** · 03-24-2011, 09:15 PM

I would like to save money on gas so i can enjoy my car on the road more often . was thinking of taking out and keeping stored away for later days my 455 and putting in a smaller engine. something that could get me in the 20 mpg hway ball park . what kind of options do i have? is this even doable?

yes, i'm a noob. appreciate any information you can give. thanks , Devin.

**BigRivy** · 03-25-2011, 02:44 AM

You can put any engine in it that you want. Will it give you better mileage? It might and then again it might not. My '71 Riviera with me in it and some misc. stuff in the trunk rolled across the scale at 5100 lbs. It takes a certain amount of energy to move a car that size regardless of what engine is pushing it. There are several ways of improving mileage that I would address before trying to change engines. Small engines would also make this car not nearly as fun to drive. The obvious things to check and improve on would be the condition of the engine and it's state of tune. Excellent ring seal and free flowing exhaust and high energy ignition system would be of help. Tire pressure is important. Synthetic lubricants in the rearend can help. But usually the real key to fuel mileage is to slow the cycling rate of the engine. The easiest way to do that is to install an overdrive transmission. Many people underestimate the difference that a few hundred RPM can make. I believe that the '71 came with a 3.23 ratio in the rearend. An overdrive tranny like a 200 4R can drop your cruise RPM by quite a bit. Probably 800 RPM or so. This by itself would add considerably to your mileage. Another thing would be to add a modern fuel injection set up. I think it would be entirely possible to adapt a throttle body set up off of a 454 Chevy big block. There are several aftermarket companies that could assist you with that project. There are many benefits to computer controlled fuel systems. The last point I will bring up that is often overlooked is driving style or habits. The way you drive or where you drive can have a huge effect on your mileage. A lot of city driving will hurt, jackrabbit starts and high speed driving will hurt. A combination of an overdrive tranny swap, crack tuning on a tight engine and improved driving habits will be probably and realistically your best bet at getting closest to your goal. Just dropping in a 350 engine with no changes to the final drive ratio would likely be disappointing from a mileage standpoint. Not to mention from a performance standpoint. 20 mpg is probably doable but remember everything is a trade off. To gain in one area you will have to give up something in another area.

**Bob** · 03-25-2011, 07:57 AM

What kind of mileage do you get now? Maybe your motor just needs a good assessment and tune up by someone who knows what they are doing.

**twoprongcrown** · 03-25-2011, 07:29 PM

@ BigRivy

thank you very much, you mentioned things that never went through my mind. the loss of power is something i had known would be a bitter sweet trade off. let the saving $ begin.

@ 9 mpg if i drive like a granny.

**BigRivy** · 03-25-2011, 10:48 PM

If you are only getting single digit mileage your car has some issues that need addressed. I have had 4 boat tail Riviera's and have put literally hundreds of thousands of miles on them and I never had one get that bad of mileage. I usually averaged about 12 mpg overall. And as a kid I drove the hell out of them. With the mandated 55mph speed limit we had back then I could get 14 to 15mpg if I actually observed the speed limit on the interstate for long stretches. Get a compression test done on the engine and get someone to look at the carb and ignition. There is more mileage to be had in your car. Just for the fish you might try to figure out if your rearend ratio is what I said it should be. Other ratios were available as an option and one could have been installed at the factory or by a dealer. What is your cruise rpm at 60 mph? You might also do some research on vacuum gauges and what they tell you and install one on your car. They can often tell you when you are driving efficiently and when you are not. Good luck.

**twoprongcrown** · 03-25-2011, 11:36 PM

I have her sitting up on blocks

have not driven her in since summer year. ( fluids and oil removed of course) so i am unsure what the rpm is when on cruise . goal is waiting for nice day no rain to ( live in portland where sun is not seen often) hope within the next couple weeks. take her down hydrate her and fix my brake lights and weather stripping. got all the stuff in the garage waiting for a break in rain. will get back to you on rpm while cruise. after than i'll take it into my guy in gresham have him look at what you mentioned and look into a vacuum gauge. i appreciate that a lot. my dad has a '72 rivi gets about 13 mpg.

**elagache** · 03-26-2011, 12:07 PM

Dear Devin,

Originally Posted by twoprongcrown

I would like to save money on gas so i can enjoy my car on the road more often . was thinking of taking out and keeping stored away for later days my 455 and putting in a smaller engine. something that could get me in the 20 mpg hway ball park . what kind of options do i have? is this even doable?

yes, i'm a noob. appreciate any information you can give. thanks , Devin.

I'm working on the reverse of your proposal: I'm rebuilding a 67 430 V-8 to put in a 65 Buick Special wagon. However, I'm hopeful that I'll actually significantly improve the car's fuel economy. The car has always been a fuel hog: 13 mpg overall. That's with a 300 V-8 and a TH-350 transmission.

My new drivetrain has one key improvement: a 200-4R transmission with overdrive. Also I'm trying to get as thrifty a Quadra-Jet carburetor as I can manage. Something else to think about is an after-market fuel-injection system.

None of this is cheap, but it is likely to be no more expensive than the complete engine swap and you still end up keeping the 455 and all the joys associated with that. Folks on V-8 Buick claim that you can get a 455 to do as well as 20 MPG on the highway with the proper transmission, carb, and tuning.

So there's hope for us classic Buick fans!

Cheers, Edouard

**sabrerattler7** · 04-14-2011, 11:13 AM

I second all comments about efficiency, except fuel injection maybe as you'll spend $3500 or more and that could buy alot of gas.
I'm running a bored and built 430 in a 68 Rivi with 3:42 gears and a 200-4R trans.On long trips with air can get 15mpg at 65-70 mph. PS. driving style has been referred to by some as agressive.
EFI VS. Carbs discussion 2009 issue of Car Craft in the What's Your Problem Column.

**elagache** · 04-14-2011, 01:25 PM

Dear Sabrerattler and Team Buick members,

Originally Posted by sabrerattler7

Originally Posted by elagache

Something else to think about is an after-market fuel-injection system.

I second all comments about efficiency, except fuel injection maybe as you'll spend $3500 or more and that could buy alot of gas.

Hey I object!

All I said was think about EFI. Thinking about them is cheap . . . . it doesn't get expensive until you actually try to buy one!!

Originally Posted by sabrerattler7

EFI VS. Carbs discussion 2009 issue of Car Craft in the What's Your Problem Column.

Seriously, could you give me a little more info on this EFI vs. Carbs discussion in Car Craft? (URL, month, ... something?) I tried to Google it and sift through the Car Craft website but didn't have any luck.

Thanks!

Cheers, Edouard

P.S. As long as I'm only thinking about EFI - I'm safe!