Okay I'm not a purist. But I love the pure perfection of the exterior/interior design of my '67 Riviera. In fact, having been a car freak all my life and having owned some 60 vehicles in my 57 years, I have come to believe that the '66 and '67 Riviera are two of the most perfectly realized designs of the 60's, if not of all time. Therefore, I love driving my gold/black '67,and do so daily, except that now that fuel is pushing $4 a gallon, and I have a bit of a conscience about the raw exhaust I'm emitting, I'm considering an engine/transmission swap, but I don't know if I can acheive even a moderate improvement in fuel consumption and I'm guessing all of these crate engines have little or no emissions equipment. Perhaps an engine, transmission, and exhaust system from a modern car, preferably Buick, that has been totalled?

Can someone enlighten me or at least point me in the right direction? I'm willing to sell a perfectly good 2003 Saab Convertible to finance turning my gorgeous Riviera into a reasonbly conscientious daily driver.

Steve Carter

I have heard it said, just today, that gasoline prices now are no greater a percentage of the average paycheck than they have been throughout most of history. I have not done the research to verify this.

Assuming this is a fact, unless we were to use our cars as daily drivers, with 15- 20K per annum average milage, how much can we seriously expect to improve the economy of any of our cars? I've owned my GS for just under 4 years now and have driven the car 7.500 miles.

I don't ask this to start a contentious conversation, but it just occurs to me that for the 2-3K needed to change to a more modern engine, you could buy an awful lot of gas, maybe 3-4 years worth even if it hits 4 bucks a gallon.

Consider this about your era Riv specifically:
* switching to anything other than a V8 is going to result in a driveline working hard to keep this size car going.
* Switching to anything American made will cost you in terms of converting to front wheel drive or having a front wheel drive transmission somehow converted to rear wheel drive application.
* Maybe a Norstar V8 would do the trick, but it's still largely a front wheel drive application.
* Diesel fuel is more expensive than Gasoline ( at least where I live)

About the best thing you could do is swap in one of the GM Overdrive transmissions from 79-90 rear wheel drive applications, that has been rebuilt to give you the benefits of the understanding of these transmissions today. However carefully consider your driveshaft because you have the two piece with the CV joint in the middle.

The other thing you might investigate is changing your rear axle gears to accomodate your driving needs. Isn't your car a 3.42 rear axle? If so you may want to see if you can drop to a 3.06 which will still provide some pep off the line and a better cruise range rpm.

But I'd stick with that 430 in there. Unless you are racing, and even then, that is a solid motor with sufficient power to move that awesome Riv. It'd be a shame to dump the original engine just to pick up 3-4 MPG.

respectfully submitted

Just thinking out loud here, but even if ya change out engine and trans or just trans, are ya really gonna save that much? No matter what you will have the same problem we all have. That amount of car is heavy I don't know if this still holds true but the old numbers were for every 500 pounds you lost one mile per gallon. Keeping the car in tune, dual exhausts, radial tires properly inflated and keeping your foot out of it so the secondaries don't open are all small things that you can do now. Just some thoughts.

I think the rear gears and overdrive transmission ideas are good ones. But the cost:benefit ratio of anything more drastic is going to be way out of whack. How much gas could you buy for the cost of converting the entire driveline? A LOT. I think $2-3K estimate for swapping out the driveline is a VERY conservative number. I think it could easily be 3-4 times that much, since you're essentially re-engineering the entire car, figure on A LOT of custom work just getting it all in there, never mind driveable, clean and efficient.

If emissions are your primary concern for such a swap, just keep the car properly tuned. You don't say how many miles you drive your car, but if it is a pleasure car and not your daily driver, then the amount of greenhouse gases you're contributing is a microscopically small drop in a tremendous bucket. If you're really concerned about it, you could probably throw a set of high-flow cats on there and see what happens. I don't know how that would work on a non-emissions car, but it could help if the engine operating as it should doesn't contaminate the cats (it shouldn't).

In this order, here's how I'd consider upgrades: rear gears, transmission, then, uh, sell the car if you can't afford to feed it any more.

Hope this helps.

Thanks for your thoughtful responses. I think I'll start with the rear end ratios, but not sure how to go about finding out what mine are or changing them, and then go to consideration for an overdrive transmission, since I don't spend much time in heavy traffic.

How can I determine my transmission ratios?

Next: Disc brakes. If I look hard enough can I find an existing thread about this?

Thanks again
Steve Carter

Never mind...just found the info on the website, and I have my mechanic already under the car.
Steve Carter

www.gearvendors.com

Makes your T400 an overdrive transmission. It's not cheap, but it works.

Steve,

Concur with Adam. If you're going to upgrade the trans, the Gearvendor route is probably the best alternative. Other options are to swap to a seriously upgraded GM O/D auto (200R4 or 700R4 for the bolt pattern) which when it's all done will cost as much as the GV conversion.

Unless you drive the car a lot, you'll be a long time recovering the costs of the driveline upgrade. Plus, whacking up the car significantly reduces it's enthusiast value as an unmolested vehicle.

I share your appreciation for the '66/'67 Rivs. In high school, a neighbor had a gold '66 that I loved.

Cheers,
JMC

My response to this topic is going to be similar to some of the other responses, however, maybe just a little bit more specific.

Up until a couple of years ago I had a '73 Chevy C-20 with a 454 V8, the fuel mileage was around 7-8 mpg on a good day. I talked to a lot of people about what could be done to improve the mileage. The suggestions ran from major modifications to the engine, switching to a 700R4 trans and re-gearing the diff from 4.10 to 3.73 or 3.42.

The trans swap seemed to be the best idea.... the cost was estimated to be around $2,800. I was already to have the work done when I sat down at a calculator and figured out what the savings in fuel and money would be over a period of time. Much to my surprise, I found that I would have to drive the truck 65,000 miles to be at the break even point. Since I only drove the truck about 6 or 7,000 miles per year the trans swap quickly became a dumb idea.

Up until the time that the truck had become exempt from the smog rules because of age, it had been classified as a 'gross polluter' which was a real pain, especially when I had to find parts to fix/replace the early emission controls.

I thought that since the truck was exempt from the smog rules, maybe something could be done to the engine to improve the mileage. I took the truck to a shop that I had dealt with before. A complete computer aided survey of the engine found that the cam was flat, the carb was way to rich, the distributer was lazy and the engine was running to cold.

All of the factory installed emission equipment, with the exception of the PCV was removed from the engine. A new RV type cam and lifters was installed, new 'Performer' intake, GM HEI ignition and the carb was leaned out. The oxygen sensors used in the late model engines were added into the exhaust head pipes so the engine could be tuned using a computer.

Upon completion of the engine modifications the engine met the requirements for emissions for a 2003 and the fuel mileage went up to 13 city, 15-16 highway.

The mechanic that did the work told me that prior to use of computer aided tuneup equipment, in his 'wildest dreams' he would never have thought it possible to lean out a carb as lean as he was now able to with the oxygen sensors and a computer.

You could achieve your goal by finding a 95-96 LT1 RoadmasterDrive train.Check the updated EPA Mileage,something like 18 & 23 MPG.and it probably weighs more than your Riv.

Well, I know that a year ago or so there was a thread here about the milage possibilities of the 69 Electra. Several people reported MPG in the higher 19-22 MPG range. So once again I ask the efficiency of reworking the factory stuff to achieve 3-4 MPG on a car that may be used less than 10K per annum?

lets see this in a chart:
10000 miles divided by miles per gallon times price per gallon

10000/ 18 mpg = 555 gallons @ $4.00 = $2,220
10000/ 19 MPG = 526 gallons @ $4.00 = 2,105
" / 20 " = 500 " " = 2,000
" / 21 " = 476 " " = 1,905
" / 22 " = 455 " " = 1,818

So if you achieve 5 MPG improvement AND drive that Riv 10K per year you can save $400.00 at $4.00 per gallon. It would take 5 years to get payback on a conversion that ran $2,000. Can the conversion be done for that amount? Meanwhile I am reminded of the year I drove my 56 one mile ( due to being too busy with other things). I've only put 7,500 miles on my GS after buying it in September of 2003.

Many people will look at possibilities which are somewhat trendy in upgrade situations. One of the first things are rear axle gears and the OD automatic trans swaps. In one respect, these are the hardest ones to pay for with fuel savings alone!

If the existing rear axle ratio is LESS (numerically) than about 3.73 (which it most probably is), then the OD or OD automatic upgrade is not really useable, especially with a carbureted engine. The OD ratio is typically about .70, so times that by the existing axle ratio to find the "effective axle ratio" when the trans is in OD. Seems like the fuel savings is about 1% for each 5% of axle ratio change?

So, if you have the more normal 3.08 ratio, that makes the effective rear axle ratio about 2.10 when it is in OD, which will put the cruise rpm (at 60mph or so) just about at fast idle. This might sound neat, but it's not. With a carb, it takes air flow through the carb to pull the fuel out of the float bowl and into the metering area of the carb. Hence, soggy throttle response at these larger loads at lower rpm levels. With fuel injection, it's a whole different ballgame as the fuel curve is determined by the computer and not air flow per se. That's how a '87 Chevy 350 TBI V-8 with 3.08 rear axle and tall tires can tolerate that rear axle ratio in OD (I drove one like that for a company truck and it worked great and could get about 20mpg average if I drove it easy).

The other thing is that with the 3.08 ratio, the vehicle will not be in OD until higher speeds, which won't save anything at lower speeds or up until it'll tolerate OD at about 70mph or more. It'll also kick out of lockup and OD pretty easy in hilly terrain, too, which is not good for comfort and such or fuel economy.

So, in order to be able to use the OD, you'll need a complimentary rear axle change to a lower (higher number) gear ratio. Better lower speed performance, but what ends up to be the same highway fuel economy as you'll not end up with the engine running slower.

One observation about late model vehicles with the newer "more gears" automatics. It doesn't matter how many forward gears they have, they all usually end up running at about the same OD rpm levels on the highway. 4-speed 4T65E or the newer 6-speed fwd transaxle, the same rpm at highway speeds in the top OD ratio.

So, to do the trendy trans and rear axle ratio swap, you'll spend a LOT of money to end up with greater performance and little fuel economy gain (having to change the rear axle to be able to use OD on the highway) at highway cruise speeds (probably worse "in town" mileage, I suspect). Not to mention the (already mentioned) re-engineering necessary to put the trans in the car to start with. Remember that almost ANY trans swap or external OD addition will also require a driveshaft alteration in length and change the angularity of the u-joints a little.

In reality, a better upgrade would be (probably) a Holley TBI fuel injection system (with the oxygen sensor kit for feedback controls), a later model HEI ignition (or similar, your preference), a better "undercar" exhaust system (i.e., possibly larger 2.5" or so pipes with quieter high-flow mufflers), and make sure you have the "hot air" air cleaner with the vac operated door in the snorkle so that the air going into the carb/FI unit is at least 100degrees F (which will allow for leaner fuel curves, somewhat). These are all add-on type situations which are external to the engine itself.

With the FI set-up, adding a pair of high-flow cats, as mentioned, would be a little better to do that if you were using a carb (due to the tighter fuel controls with the oxygen sensors). With the cats, you'll probably want to consider wrapping them in ThermoTec or similar or fabricating some aluminum heat shielding for the floorpan from the cats (as GM and others did). Still, with modern fuels and the FI system, you'll probably end up with something that will meet emissions standards of much newer vehicles.

The advantage of using a 3-way catalytic converter is that it'll also reduce NOx emissions plus HC and CO. Still, using modern technology to upgrade older vehicles is a very viable situation at this time! Unfortunately, it'll take a good while to hit the "break even" point of what's been spent (which is why you use less expensive methods which don't/won't have to result in a lot of re-engineering to graft in different engines and/or transmissions).

By the same token, the Rochester Q-Jet is HIGHLY tuneable (as the 454 pickup example mentions). BUT it takes somebody that really knows how it all works to get the desired results! In that respect, the Holley TBI FI system is a complete bolt-on kit, but it's not really "cheap" either. I really feel you'll get more cost-effective results with making the engine a better fuel conversion device than going the trans/rear axle change routes!

Regards,
NTX5467

Having done this swap a few times with the 430 and 455's I can say out of all the options, an overdrive trans swap is the best and most cost effective. The gear vendors add on unit will not work within the confines of the Riviera X=frame, and may pose a trouble with eliminating the center bearing.

I prefer to use 700r4 cores from 87-93 GM cars, mainly corvettes and camaro due to the better stock calibrations. In the past, my total inventment in the trans/rebuild, new convertor and a trans cooler was under $1000. YOu may or may not have to cut the driveshaft, I dont remeber the length of the 400 or 375 but i think they were close. You'll also need to set up the TV cable and adjust it properly....very important!

If the engine is bone stock internally, a 3.08 (which i think was stock in Rivi's) is the lowest you should go with a 700r4. a 2.73 will drop the rpm too low in 4th gear around town. 3.08 and 3.23 are excellent. On the upside, the off the line performance is great because the 700 has a 3.06 first gear AND the overdrive will put your 430 at a happy 1900 rpm at 70-ish mph - it was a 700 rpm decrease on the one car over the 3 spd. It also had gains of 4-7mpg dependant on the terrain and speed.

SO! parts list
700r4 from 87-93 GM
Convertor Lockup kit
TV cable and bracket
TCI or Trans Dapt Trans mounting plate (mounts chev trans to BOP)
Slip yoke and maybe a conversion U-joint

Avoid the Holley EFI - it nice if you have one of their exact engine configurations or you're a whiz at tuning EFI cars / stick with tuning the carb and reading the plugs along ith all the other old hand tricks previously mentioned in this post! Good luck!!

Your swap is good I have a 67 Riv slightly modified 430 I would like to put the 700 or the 200R in but I am not sure if the drive shaft of the 200R will fit also what type of shift linkage did you use to make it work. whereas I have a columne shifter if you have any input please share.

This is a great thread, love the talk on efficiency with our older cars.

LT-1 is still spelled 'chevy.' I think that you could put in a mildly modified 200r4 (dual pattern bell housing will bolt up to your 430.) You'd need to modify the carb linkage to work the throttle valve on the 200r4 (no modulator like the turbo 400) http://www.tvmadeez.com/

One really nice thing about the 200r4 is that the distance between the bellhousing and the transmount is within 1/16" of the 400's transmount. A little grinding and it will bolt in, but you'll have to get your driveshaft length made to fit.

Reconfigure your shifter for the o/d. http://www.shiftworks.com/buick.htm

The only other thing you need to do is some wiring so the torque converter will lock up. http://www.jegs.com/i/TCI/890/376600/10002/-1

You could also look at some of the aftermarket EFI units to help with fuel delivery. I've found that a properly tuned Q-jet can give you both good mileage and performance.

One thing a lot of guys don't consider when trying to increase gas mileage is tires. Both the circumference and the rolling resistance can have an effect on your mileage. Those 50 series tires sure look good, but it takes hp (gas) to roll that much rubber along the road compared to a 70 or 75 series tire.

I found wmsteed's post about making adaptations for computer tuneups to old engines very enlightening. I'd go that route first before anything else.