Early 70's Cadillacs and fuel efficiency.

frenchyd said:

In reply to Nick Comstock :

Please don’t do it.  Yes you can and maybe you’ll achieve your goal.  

However,  there will be one less 70’s Cadillac.  Which as you point out has unique characteristics. 

One  of which is poor fuel mileage.  When you are done with it who will want it?  Most buyers won’t care that you’ve almost doubled the fuel mileage.  They will want originality. 

does anybody actually care about malaise era caddys? They are probably the worst for all aspects of Cadillac ownership. Big engines that put out little hp, poor mileage, questionable styling, poor ride, and they were certainly not put together all that well.

In reply to Nick Comstock :

My '72 CDV was very similar to that '71.  The 71 grill had a cross pattern.  72 had a predominantly left/right pattern and 73 had a predominantly up/down pattern.  73 had smaller backup lights in the massive rear bumper.  Otherwise, they were all the same.  Mine had the "landau" half vinyl top like the 74, versus the full vinyl top in your 71 pic.  My aunt's was like your 74, but red with a white landau top. 

frenchyd said:

In reply to Nick Comstock :

Please don’t do it.  Yes you can and maybe you’ll achieve your goal.  

However,  there will be one less 70’s Cadillac.  Which as you point out has unique characteristics. 

One  of which is poor fuel mileage.  When you are done with it who will want it?  Most buyers won’t care that you’ve almost doubled the fuel mileage.  They will want originality. 

There are plenty all original, low mileage and garage kept Cadillacs out there. 

I don't modify my junk for other people.  I'm not concerned about resale in the least. I've lost my ass on almost every car I've sold so that's not even a consideration. I lost close to 9000 on a 1982 BMW 320IS once all the receipts were added up. I may not be smart but at least I'm enthusiastic.

This could turn out interesting.

DO IT.

Nuff' said.   

In reply to mad_machine :

That's harsh man, harsh. 

I disagree about the poor ride part. Maybe handling is what your referring to? Because they do not handle but I'd have to drive for hours to find a corner that a fully loaded semi truck couldn't take at 90 mph so I'm not concerned with that.

Nick, you and I are a lot alike...I am actually building a vintage-car EV on paper and have been delving into the ins and out of figuring it out.  For my wants and budget it seems prohibitve. But for $10k it may be more likely to get done. The batteries, motors and  controllers all play a part in range.

On the diesel side, just for an experiment I made some of my own bodiesel. At the time I really wanted a little truck that ran on veggie oil or bio-diesel.  It's totally doable and is taking waste and turning it into fuel. Plus if you ever get jammed up you can just pull into the nearest fuel depo and get a tank of the regular stuff.

There was a cross-country renewable fuel car race from I think San Francisco or thereabouts to Los Vegas. I think the rules were that you could not buy fuel along the way.  There was a guy that sold Locost parts.  He built a Locost, put a small Diesel engine in it and entered the race.  And won, of course, because "hippies" and he was the only car to finish.  He would just stop along the way and get some free waste fry oil.

 I like the idea of maximizing the current engine with an overdrive trans. You may wind up with too tall a final drive in O/D and need to change the gears. Likewise a cam swap may help but I'm not the one to figure that out. Matching torque curve to speed etc...

The late 70's V8 could be had with TBI injection, so the manifold is already out there, just add a TBI unit and megasquirt. The HEI is already pretty good, but you could play with crank triggered DIS to squeeze that last bit of control.  Add a good exhaust, modern catalysts, and see what you get. Do have a friend at an emission check station? you could test the car as you go to see your results.

 Read an article recent about an engine swap in a large RV. Went from a carbed 454/TH400 to a 8.1 (496) Vortec with Allison o/d trans. Fuel economy went from 6 to 11 and at a much higher cruising speed. (from 55 to 70).

mad_machine said:

frenchyd said:

In reply to Nick Comstock :

Please don’t do it.  Yes you can and maybe you’ll achieve your goal.  

However,  there will be one less 70’s Cadillac.  Which as you point out has unique characteristics. 

One  of which is poor fuel mileage.  When you are done with it who will want it?  Most buyers won’t care that you’ve almost doubled the fuel mileage.  They will want originality. 

does anybody actually care about malaise era caddys? They are probably the worst for all aspects of Cadillac ownership. Big engines that put out little hp, poor mileage, questionable styling, poor ride, and they were certainly not put together all that well.

I think they’re awesome,  like the looks,  don’t care about mileage, like the soft floaty ride (I mean I’m not expecting a sports car),  and think they’re screwed together just fine.  IMO real cool cars if you come in with realistic expectations.  I mean plenty of people poke fun at LR Discoveries,  but they still have fans,  right?

In reply to Gearheadotaku :

I've looked into what some of the guys that are putting in the Holley Sniper injection and the like are reporting and they seem to not be doing any better than a well tuned carb. Other than advantages in starting and varying weather conditions I'm not sure a TBI setup will get me where I want to be. 

Some gas stations are so far apart in Texas that I don't blame him for wanting to double the mpg. 

mad_machine said:

I like the idea Nick. If you went with the LSx route, I would find the nearest 2wd pickup or van you could find with the chosen engine and swap the whole thing in. 

 

This is what I would do. You keep everything that makes a big old Caddy a good road trip car and add in a drivetrain that you never have to touch while on the road. In addition to whatever mileage gain you get there's a lot to be said for a modern, trouble free drivetrain. 

In reply to Nick Comstock :

I've not heard much encouraging about Holley EFI....

Yes, a properly set up Quadrajet is a good thing. Many people (including me) just don't know how.

I’d totally enjoy going down the road in a fleetwood talisman 

alfadriver said:

I'm not sure why the original 3 speed w/o a lock up converter would be better than the original donor 5 or 6 speed with a lock up converter.  And a calibration that is already set up for that transmission.  Less stuff being taken off the donor engine is a good thing.

I am assuming 4 speed auto, meaning 4L60, which is an updated TH350.  If it's the 6 speed auto (6L80, or Allison) then the trans controller is a separate module.  Also a lot more money.

Those old non-lockup converters were actually pretty efficient once past the stall speed, given that they didn't really have any other options at the time.  Detroit was also pretty good about making sure that cruise RPM was at a higher speed than the stall speed.  Conversely, modern converters with lockup clutches can be as inefficient as they want. 

With as tall as the gearing was on those old Caddys, I'd think that anything small like a 6.0 or 6.2 would constantly be kicking in and out of overdrive.

And taking a smaller dimensional engine and putting into a HUGE hole should be pretty easy- the part that needs the most fabrication are the mounts.  After that, plumbing the cooling system- and, again, perhaps some fabrication so that you are using more donor parts.  Including A/C.  

A/C is actually one of the PITA parts of the swap because the LS has the compressor mounted low, right where the frame is on older cars, and because of this the LS has the right side engine mount shifted back a few inches relative to Everything Prior.  There are adaptor brackets to mount the compressor up high, but then you are buying more parts, you are inviting compressor failure because the oil doesn't travel back down to the compressor (the reason GM mounted it next to the oil pan in the first place), and there are issues with putting a high-torque, high-vibration accessory hanging off of a stick instead of bolted solidly to the engine block.

The "hole" in those older cars is not all that big, really.  The HVAC stuck out into the engine bay, and those Caddy engines were not very large.  They had long bore centers (5.0", IIRC) but they were lower and narrower than, say, big block Chevys.  Detroit was not very terribly concerned about packaging at the time, when if they had any issues they could just make the car externally larger, which they could also charge more for...

rslifkin said:

I'd definitely use the more modern trans with OD and lockup.  If you don't change to shorter diff gears to get better performance off the line (which still probably won't be terrible, as the modern trans likely has a lower 1st gear), you'd just end up with having a trans that can't / won't (might require tuning changes) use its highest gear until a fairly high road speed.  

New problem:  Cadillacs had a different rearend than the Chevy 12-bolt.  You can't really get gears for them.  So a gear swap is going to first require getting a new rearend.  Not sure if contemporary B-body housings bolt in or not.

The other factor in why my gut reaction is a simple Chevy-to-BOP adaptor, and keep the TH400.  The easiest swap is the one that you don't do in the first place....

And at that point, it's also easier to just keep the damn 472 and do a supertune on the carb and tweak the ignition timing.  (Maybe lock out the distributor and use it as a crank sensor for a coil-near-plug Megasquirt ignition-only installation)  You could convert it to EFI, but I am not convinced that EFI can get economy as good as a well tuned Quadrajet.   It's a small cam, and small ports make for ferocious intake velocity.  Combine that with decent manifold heat, and you could run it lean until the spark plugs melt and the engine wouldn't care.

Knurled. said:

alfadriver said:

I'm not sure why the original 3 speed w/o a lock up converter would be better than the original donor 5 or 6 speed with a lock up converter.  And a calibration that is already set up for that transmission.  Less stuff being taken off the donor engine is a good thing.

 

I am assuming 4 speed auto, meaning 4L60, which is an updated TH350.  If it's the 6 speed auto (6L80, or Allison) then the trans controller is a separate module.  Also a lot more money.

 

Those old non-lockup converters were actually pretty efficient once past the stall speed, given that they didn't really have any other options at the time.  Detroit was also pretty good about making sure that cruise RPM was at a higher speed than the stall speed.  Conversely, modern converters with lockup clutches can be as inefficient as they want. 

 

With as tall as the gearing was on those old Caddys, I'd think that anything small like a 6.0 or 6.2 would constantly be kicking in and out of overdrive.

And taking a smaller dimensional engine and putting into a HUGE hole should be pretty easy- the part that needs the most fabrication are the mounts.  After that, plumbing the cooling system- and, again, perhaps some fabrication so that you are using more donor parts.  Including A/C.  

 

A/C is actually one of the PITA parts of the swap because the LS has the compressor mounted low, right where the frame is on older cars, and because of this the LS has the right side engine mount shifted back a few inches relative to Everything Prior.  There are adaptor brackets to mount the compressor up high, but then you are buying more parts, you are inviting compressor failure because the oil doesn't travel back down to the compressor (the reason GM mounted it next to the oil pan in the first place), and there are issues with putting a high-torque, high-vibration accessory hanging off of a stick instead of bolted solidly to the engine block.

 

The "hole" in those older cars is not all that big, really.  The HVAC stuck out into the engine bay, and those Caddy engines were not very large.  They had long bore centers (5.0", IIRC) but they were lower and narrower than, say, big block Chevys.  Detroit was not very terribly concerned about packaging at the time, when if they had any issues they could just make the car externally larger, which they could also charge more for...

Except that I'm talking about using a 6 speed donor vehicle.  So there's no extra expense either in finding it or controlling it.  

And forgive me for not fully buying that old converters are more efficient than I think- regardless of how efficient they are, they are not nearly as efficient as a locked converter.  So if you are spending most of your time cruising, all that time is lost.  Besides, there's no reason to get rid of the original rear end- so you will have the overdrive (which the original 3 speed does not) as well as a tall final drive.  Best of both worlds.

The key us using the donor vehicle, where the controls and calibration are already done for you.

And I'm sure A/C can be worked out.  On one hand you say the hole isn't big, and on the other you say that GM would just make more space and charge more for it.  

GRM just put a fully dressed, with AC, into a modern Z car.  Because of that, I just can't see putting the same powertrain into a old Caddy would be terribly difficult.  Granted, the Z used a lot of components from the original Z car, but still...   There's no way the engine compartment on a modern Z is anywhere near as spacious as a '71 Caddy.

I've daydreamed if making an old Caddy into a trailer park hybrid. Connect a big ass electric motor to the input shaft on the trans. In the big empty hole where the big block used to be, drop in the biggest Harbor Freight generator that will fit. Run the motor off the generator. 

Probably wont work but how will we know unless we try?

I still love this idea.  I don't get the people quibbling over the validity of the gains, I get the OP 100%.  He wants a cool classic cruiser that doesn't drink like Ollie Reed and smell like you choice of cologne is Eau de-burning dino.  Like hybrids or electric cars, you can argue all you want that they are overall worse for the environment than a Suburban, but it still makes sense from an enjoyment, usability and control of where and how the pollution is created.  

I've poked Wawazat to chime in.  He's added one of the aftermarket TBI systems to his Cougar of a similar vintage so he'll have first hand knowledge or the hows, whys and most importantly results to see if it would work for this.  Now, we just need to find a bolt in 4 or 5 speed overdrive trans solution for him too.

In reply to Knurled. :

Gearing shouldn't be a big issue with the right trans.  It might be for the 4sp autos, but at least with a 6L80E, the gearing spread is actually surprisingly appropriate for the tall factory gearing in those cars.  

Adrian_Thompson said:

I still love this idea.  I don't get the people quibbling over the validity of the gains, I get the OP 100%. 

I am with you there. Very few people love the 70s caddys, so turning one into the car of your dreams should not get anybody's knickers into a knot. How or why Nick wants to do it is not up for discussion, he has a plan and wanted help in how to do it. This is a group that thinks everything should be LSx or Rotory powered, but then moans that a caddy should have the more inefficient engine built in modern times?

For the AC don't use the 1971 pump, it probable takes several HP to turn, plenty cold but not good for mpg. 

On the other hand the factory air works very well and the pump is already positioned way out over the passenger wheel well about two feet away from the crank.

One of the first cars that I drove was a 1972 Olds 98, 455.  Even with the hiway gears it could spin a tire if you wanted too.  It would cruise any where from 55 to 115 with little care and lots of gas.

I had a chance to buy it back from the next owner but didn't because it took up too much room.   Someday I'll get an old boat again.

Another thing that just popped into my head. I wonder how much of a weight difference there is between the two drivetrains and how that may effect ride height and ride quality?

In reply to Nick Comstock :

May be pretty even- assume that you get a iron block LS, the large size of the big block would likely be offset by the lighter and simpler 3 speed trans, compared to a new iron LS and 6 speed.

Adrian_Thompson said:

I still love this idea.  I don't get the people quibbling over the validity of the gains, I get the OP 100%.  He wants a cool classic cruiser that doesn't drink like Ollie Reed and smell like you choice of cologne is Eau de-burning dino.  Like hybrids or electric cars, you can argue all you want that they are overall worse for the environment than a Suburban, but it still makes sense from an enjoyment, usability and control of where and how the pollution is created.  

 

I've poked Wawazat to chime in.  He's added one of the aftermarket TBI systems to his Cougar of a similar vintage so he'll have first hand knowledge or the hows, whys and most importantly results to see if it would work for this.  Now, we just need to find a bolt in 4 or 5 speed overdrive trans solution for him too.

As Adrian noted when the Edelbrock 4 barrel carb that was I stalled by the PO on my 351 C powered ‘69 Cougar convertible backfired and failed I swapped it for a FiTech TBI system. I had a good AL manifold and wasn’t intetested in modifying it with bungs for injectors. It’s a bop around car and I wanted good driveability without the continued fuel scented clothing after a drive. I installed it in my driveway summer of ‘17 and have added about 1000 miles.  MPG increased driveability improved and fuel smell post drive is non existent. I’m still playing with tuning parameters but reduced fuel use  about 25%. It’s still nothing to get excited about however. My trips in the car are mainly surface streets and I tend to wind up the car (manual trans) because I enjoy listening to the Cleveland rev.  I’m still cutting fuel when I make adjustments so I’m confident I can reduce fuel use more than I have thus far. Other then iD10t errors during my install and a persistent electrical noise issue I ran in to the car runs well.   Not sure you could cut fuel usage by 50% however.  I am installing a 5 speed TKO600 this winter but am also swapping rear gear ratio as well.

Im adding my reply while in my GMC L86 powered Yukon. 6.2L aluminum block and heads 420 HP/480TQ and much better fuel mileage with the auto trans. Worst fuel mileage in the bus is better than best fuel mileage in the convertible. 

The way I see it is try the TBI swap in the 472 then tune for MPG. All the feel of how the Caddy gods intended.  I’ve got a GM TBI that I scores in the GRM New Years game if you are interested in that path. I can offer guidance and support for FiTech or Sniper install if you want to go that way. I’ll be of no help on Sniper tuning though.