This is not as easy a question as you think. I have a 1971 vista cruiser with a 455 2b and 5 speed stick 253 rear end 245X60X15 tires. I was thinking I should convert it to aluminum intake and 4b to gain power. Then an old drag race friend said maybe not the best option.

So here is the question: Don't just say yes, you have to evaluate the application too. Big station wagon with a 250ish rear end and 2 inch dual exhaust. The t5 five speed is not known for its ability to handle power. I want a good driver with the best mileage I can get. If I want to go fast I can drive one of my other cars. So what do you think. The engine pulls fine with the 2b carb but is a bit of a slug.

Let me know what you think but think about it before you answer. Also I dont own a 4 b manifold and carb and would need to buy one. Torque vs horsepower??????????

Lee

 

Imo a Performer with a smallish 4 barrel, maybe an Avenger 670, something of that nature, might work well. It'll run on the primaries around town then when you put you foot in it you'll get all 4 barrels.

 

I would not be surprised if a swap to a 4 bbl not only gave you more power, but might result in a little better fuel economy, too. That said, not sure the gains will be enough to justify the trouble and expense. If you already have another hot rod(s), leave the wagon alone.

 

The T5 is what worries me. That thing is on serious borrowed time.

 

Actually the Rochester 4bbl carbs can give you better fuel economy if you keep your foot out of it. ( because the primaries are smaller than on the 2bbl's). Then you have instant backup power if you want(need) it. Big blocks like to breathe. Think of having only one lung. Sure you can get by, but it's nice to have that 2nd one when you need it. Don't know how this fits into the equation with the rest of your drive train though. Chumley

 

The old maintenance records show the t5 has been in the car more than 10 years and 30k+ miles with one clutch replacement. That is a good concern though, "burn rubber in first and buy a new transmission." Big incentive to burn the rubber in my 1971 442 beater. Of course that car has a numbers matching M-22 which would hurt more that a $500 t5.

Lee

 

You should read the articles "Turnpike Cruiser" in Car Life magazine from April, 1967 and "Olds Swings a Pair of Keen Cutlasses" in Motor Trend magazine from February, 1967. They discuss this comparison in some (somewhat hyped, 1960s) detail.

They had been available on WildAboutCars, but I can't seem to find them now.
The upload format of CO prevents me from posting them here in a recognizable form, but I can send them to you if you PM me.

- Eric

 

I agree with Chumley - Q-Jet is the best of both worlds!
Helped a friend with a 73 Monte 350 - Q-Jet gave him 4 more MPG, and ***** if he needed it!

 

Take the 2:56 rear out & put something like a 3:08 in it at least.Gears are a torque multiplier,and the engine will not have to work as hard to get it moving,thus more efficient.With a 5-spd,you could put a lot more gear in it,and still be fine.

 

with a heading like only for the smart people AKA the cool people
I didnt know if I should respond to this or not ?

 

there may be an aurgument for increased economy w a 4 barrel if you keep your foot out of it, but lets be realistic...if you have it can you keep your foot out of it ??? I cant so any economy goes right down the carb throat

 

Sorry, but with all due respect to Brian, I absolutely disagree with this.

Lee specifically said that he will not be racing this car and has another car to go fast in.
He's already got a 5-speed, which lowers his first gear to a very reasonable level.
The stock Olds motors, especially the big blocks, are FAR more efficient at low RPMs (where you would be lugging a smaller motor) than at high RPMs, and have excellent low-RPM torque to get moving well enough for peppy traffic performance even with ridiculously tall rear end ratios.

If this were any kind of a modified motor, or if he wanted to "blow off rice burners," then I would agree, but for the application he just described, I think the talk rear and 5-speed is just right.

edit: As far as answering the original question, I would say that Olds probably made the original Turnpike Cruiser with a 2GC for a reason, and I'm guessing it was improved throttle response at part throttle, though I know that in theory the QuadraJet should do better in that area.
I'd still recommend a well-adjusted QuadraJet over the 2GC in a low-comp., low-revving 455 for both mileage and performance, with the caveat that after spending the money and doing the work, you might not actually improve either of those very much, for the above-mentioned reasons, and also because the engine may not exceed the 2GC's CFM capacity until the very top of its normal operating rev range, thus adding little advantage to the large secondaries.

- Eric

 

Now the discussion is getting interesting as I expected it would and Firefrost by the term smart I meant I don't understand the torque and horsepower thing well enough to know the answer and was surprised by my friend's response to the change. Most people think the way I do about 2b vs 4b neat to have the extra horsepower. I am still not sure that is correct in this application. If I wanted to race around town I would not have bought a VC. But the application of a cruiser has lots of appeal. Turn on the ac and get 16 mpg on the road in a vintage classic car cruising to a show.

A couple additional things to know about the characteristics of the car. It has a .6ish to 1 fifth gear which makes about 1400 rpm at 65 mph with the 245X14 that are on the rear now but it is going to have 245X15 on the rear. At the 1200 rpm it will pull a gradual hill without any hesitation or heavy throttle necessary. Brian changing the rear end would cost the same as a used craigslist aluminum intake and 4 barrel and air cleaner since I already have a 323 12 bolt in my other VC but the driveshaft may not be a direct bolt in.

Another note where too much of a good thing is I had 275X15 on the rear and the car would not beat a Yugo out of the hole. I was thinking about taking it to Bonneville salt flats to set a record.

Finally, cost of modifications in gas savings given a low driven car does not appear to be cost effective. Does anybody have the torque/hp of the 2 and 4 b 1971 low compression 455. Finally, some more response would be nice going through the gears.

Lee

 

Good morning Lee
Years ago I had a 1971 Vista Cruiser 455/2bbl, 3.08 gears and I was impressed with how much pep the 2bbl provided. I don't know what the cfm was, but I'd have no problems using that as a daily driver.

Then I had a 1968 Cutlass with a 350/M21 and 3.08 rear end gears. It felt like I had to slip the clutch to keep it from leaping across intersections, and evetually swapped in a 3.31 rear end I found. I liked that much better. You mentioned it had a clutch replaced within 30,000 miles and that may be why. How does it feel to you? Are you comfortable with the driveability?

If you have a 2.56 rear end now, then add a .6 overdrive you down around a 2.14 in 5th gear. If you put in lower gears that ended up with the 2.50ish final gear ratio you'd still get pretty good milage and more snap around town.

It's all on what you want out of the car. If just a fun driver with mild performance I'd stay with the 2bbl and swap in the 3.23 from your other car. Spend the money on a new driveshaft rather than the carb/intake. And back to Richards comments, you'll need to keep it mild to make the T5 last. My 2 cents. John

 

John: You are correct. It is a really difficult car to smoothly get all that weight moving from a stop. Especially when it is on an uphill stop. I have driven a stick car all my life and often have to think about the start when it is natural for me to drive a stick. I had my first automatic trans car about 6 years ago so am a lifetime stick driver and should be able to drive anything.

Lee

 

In light of this fact, I will change my previous advice, Lee and Brian.

If, in practical use, your first gear is too high for comfortable starts, then it needs to be lowered.
I would still advise against making it TOO low, as your highway mileage will start to suffer, but a 3:08 or 3:31 or so might be just the thing.
You'll lose your 1,400RPM cruise, though and your 200+MPH top speed .

 

I am now thinking the 323 12 bolt out of the other vista cruiser would be the best change I can make or if I could find a 308 open ten bolt locally that would be the easiest. I am going to add a rear sway bar anyway so I will be messing with the rear end. I could vary the characteristics of the car with tire size and get the best possible combination of performance and economy. Leave the 2b after reading some of the turnpike cruiser articles sent to me. Thanks for helping me think this through. I still think we have not fully discussed why olds even made a 2b and the merits of this combination.

lee

 

Werent two barrel carbs sort of the norm back then ? Have seen and worked on lots of Truck's and dialy drivers with a two barrel carbs

 

For more power and mpg you might consider mods to the exhaust. If you only have 2 inch exhaust maybe go to 2 1/2 and putting in a H pipe and turbo mufflers if you dont already have them. Not sure if they make headers of any kind for that car. Maybe the 442 cast iron manifolds if you could find them cheap.

 

the 3.23 gears would also help the clutch and tranny live longer... all that torque has to go somewhere...

 

My 72,when it was carbureted,has the 507,with an 830 Holley,3200 stall converter,TH400,and 3:73 gears,and it could easily get 12mpg,and a few times almost 14mpg.I drove the car an hour to a nearby track,clocked off a pass 10:98@122mph,then drove back home.If can can do that with this,you shouldn't have any problem doing it with a 5spd,a decent gear,and a more mild of an engine.
We could take a few more examples:
About 15 years ago,I had a nice 85 GMC 1/2ton 4x4,with a mild 350 in it,with 3:08 gears.The truck originally came from the factory with an overdrive,but when I got it,the TH400 was already in it,so that coupled with the 3:08's,and 31" tires,made a dud that could barely get out of it's own way.I would get about 6mpg wherever I was,around town,or on the highway.One summer,I dropped both axles,and rebuilt them with 3:73 gears,and added a posi in the back.I made no other changes.Just the gear change alone almost doubled my mileage.I didn't have to put my foot to the floor to make it go anywhere.
Before the truck,I had an 89 Mustang 5.0L,that was all stock,with 3:08 gears.I would get about 18mpg with that car.I installed 3:73's in that,and I started getting about 22mpg.I then swapped the deadweight AOD automatic,with a T5,and started getting 26mpg.
Then there is my current truck,a 2002 2500HD,with 6.0L,and 4:10's.Everything is the way it came from the factory.I would not change a thing with this truck.Empty or loaded,it gets about the same.I get every bit of 18mpg with this.Only when I hang my 700lb v-blade on the front,and run 4wd,does the mileage dip down.

Is there such thing as too much gear?Absolutely.You can get to the point where the engine is spinning past the power band,and working harder to keep going.

 

When I went through this with my turnpike cruiser, I found that I love the 308 gears. And if I remember correct, I was able to use the same housing. Its been many years since I did the project though, so someone should double check me on that. I believe that if I wanted to go any deeper, I needed to do a complete rear end swap. I saved a lot of money and time at any point. I also ended up going with the spread bore carb like chumbley had talked about. My car was still very drivable and fuel friendly.

 

From what I understand you want power but don't want to spend much money. I see the following solutions:

1. Make sure your engine is in perfect tune.
2. Change to a lower rear gear ratio, maybe update to a posi.
3. Increase the timing (depends on many factors)

I personally would not spend a dime. If you have money burning a hole, I would start with changing your gear ratio & keep the intake & carb stock.

As a side note, have you checked engine compression? Have you thought about updating your ignition and or heads? Which carb & exhaust manifolds are installed? Have you had your vehicle on a dyno so you have a base line?

I'm surprised your exhaust is 2" and not 2 1/4 or 2 1/2. Maybe update your exhaust with cutouts

 

As a general rule, high ratio rear ends like a 2.56 are installed ONLY in auto transmissions, and low ratio rear ends above 3.23 and up are installed only in manual transmission cars, with a few exceptions,(mostly high performance applications) which you specifically said was not your goal. I think you would gain both mileage and better driveability with a lower rear end gear, or installing an auto transmission with your 2.56. I don't think a 2bbl to 4bbl I don't think will change much.

 

I don't want 442 performance, just responsive drive-ability and mileage.

Engine tune is great and distributor was converted to electronic by prior owner. Runs great on pump regular gas. New wires and plugs. Exhaust is 2 1/4 to the back with turbo mufflers and 442 exhaust manifolds. I mistated when I said 2". Large open element air filter too. I think everyone agrees that if I go the the 15" rims and 245 tires I need to deal with the rear end ratio and I think 323 would be perfect with the overdrive 5th gear.

Lee

 

Yup,you've got it.

 

Wish I could chime in on this one...why did you have to put a qualifier in the question?

 

It is interesting that Olds is the only GM division to put a 2 BBL on its biggest engines. I know there were some 2 BBL Pontiac 400's but I don't believe there were any 2 BBL 455 from Pontiac of Buick or Chevy 454's.

 

AH64 I already took credit for being the dumb guy in this thread asking for the opinion of people that know engines, 492hp probably means you know engines. Lee

 

Lee,

In 1970 they had a SX that was a turn pike cruiser, it was a neat car and of course part of a package. I would change the rearend to a 3.23, and if you want add a posi unit at the same time for towing. Well thing that was not discussed is the fact that a two barrel has larger butterflies than the rochestor 4bl carb (rochestor), therefore, it changes the response and the power band. If it runs fine then I would leave it alone. Again, it all depends on what you would like to do with your car.

 

If I recall correctly there was 2bbl 396 (station wagon motor), but I don't remember what year.
I have a feeling I also heard of a 2bbl 454 truck motor, but, again, the details escape me.

- Eric

 

Ok, so I have an idea...scrap the carb and put a 4bbl set up on it, then put a gear vendor overdrive behind the trans, and a 3.42 rear. That'll give you great off the line (city) performance and also allow you to cruise w/ a 2.53 ratio (hwy)...

Seriously, you could just put a 3.42 gear in it and see what she does, I believe you mentioned you already have this part If that doesn't help then try a small 4bbl set up on it. I've got a 600 cfm Edelbrock (Carter) I'll GIVE you for the price of shipping.

I figured my mileage at 9 + change...and that's with a 468 CI, Holley HP950, & 3.42 rearend cruising at 2800 at 60 mph. I don't think the 4bbl will hurt you much.

 

IN 71 and 72 pontiac had a 455 2v 180 hp and 200 hp