These engines I hear are surprisingly not nearly as heavy as their prodigious cubes would suggest. I think a 472 / 500 scales quite a bit less than a big block Chevy or Ford. Swaps for these are interesting. I hear that they are excellent choices for square body GM trucks and I’m not surprised as the torque would match a pickup’s use perfectly.
So in the idea of keeping less that totally inefficient- aka with an constantly open torque converter with just 2 or 3 gears- is there anyway to swap in a more modern 5 speed with a lock up torque converter? Seems to me that it would make it a lot more livable. Like big trucks that have a lot of gears since they don't spin, I wonder if this would benefit by that, too. Maybe with enough ratios, you could even lower the final drive of the rear....
The thing is that the TH400 is a fairly compact trans, and the car has a transmission tunnel to match. I could hook it up to a modern trans but that requires rebuilding the trans tunnel which means the interior is coming out and I'd have to get new carpet, etc. 4L80E might fit, but then I have to deal with electronic speedometers, a standalone controller and new sensors. This is a matter of limiting scope - I've got enough on my plate with this car already beyond the engine swap. If the scope creeps too far, it'll stay parked because I'll never get to it.
This will not be an everyday commuter or be doing cross-country trips on a regular basis. Having the car basically be as-built is just fine. Ineffeciency, well, I can accept that in this case.
In reply to alfadriver :
These engines kill manual transmissions. IIRC a guy going by Caddy Carlo used to put manual behind them. I think the recipe was drill the back of the crank for a pilot bearing, use a Pontiac big block flywheel that's been drilled to Cadillac pattern and the strongest trans you can afford. Replace trans as necessary. These all came with 400 trans and the factory just put in tall rear ends to let the torque of the engine take over but also keep revs down at highway speeds.
Edit now I see you were talking about a 5 speed auto with lock up. Some people have put built 200 trans behind one since they have the BOP pattern. But honestly if you're looking at these engines then fuel economy isn't a priority.
Apparently my '66 has some sort of two-stage torque converter that makes the engines feel even torquier than they really are.
Switch Pitch!
I wish somebody made an old-school converter that would electronically lock. Do they? I've never seen one.
I had an old '70's Corvette back in the day with a non-factory big block. I remember in the winter when it was cold it would run 60 mph at 2300. After a few mile when the fluid got hot, it took 2600 to achieve 60. I hate non-lockup converters. Unbelievable that that's all we used to have.
Vigo said:Apparently my '66 has some sort of two-stage torque converter that makes the engines feel even torquier than they really are.
Switch Pitch!
Switch pitch with an early caddy bolt pattern.... pretty rare these days.
The switch pitch is nice. You'll find that more gears are a complete waste with a big cube engine like the 472. Honestly, you'll be traction-limited with 2.73s and a Powerglide. You can't think of them in traditional gearing mindsets. I did a 500 for my 66 Bonneville when I was setting it up to be a tow pig. The 10.5FF axle I stuffed in it had 4.10s. Crazy mismatch. 3.08s would have been more than enough torque multiplication for whatever weight I threw at it.
You could find some kind of lockup TC, but it won't be easy. You'll likely need a 4L80E with a stand-alone controller and some sensors added on. Then you'll still have to adapt the Chevy pattern to the BOP engine. The only BOP-pattern transmissions with a lockup option were the TH350C and THM200C. The 200 won't handle the torque. They were a tiny thing that was only used in the lowest-output vehicles from the late 70s through the 80s. They didn't even last behind a 140-hp 305. The 350 could be built to take the torque, but it won't be cheap.
I actually have exactly what you need if you choose to go this route. Some of the 6.2L diesels that made it into the P-vans and other medium duty applications used a really low-stall converter for the TH400. They are super beefy. I had SunCoast fab me a special one with re-curved fins, furnace brazed. It has the 6-bolt flexplate pattern too. I opened the really big wallet for it, and behind my 500 in the Bonneville (with 3.23 gears) I got 18mpg.
Think the opposite when it comes to "performance" with a big caddy. Lower stall, higher gears, fewer trans ratios.
I would suggest TH400, high 2.xx gears (probably already have that) and buy my canoe... I mean torque converter. I just want to see it used.
Stampie said:In reply to alfadriver :
Edit now I see you were talking about a 5 speed auto with lock up. Some people have put built 200 trans behind one since they have the BOP pattern. But honestly if you're looking at these engines then fuel economy isn't a priority.
Actually, they do quite well in the MPG category. Low rpms, nearly zero valve overlap, Qjet carb. My low compression 500 did 18+ in a 66 Bonneville with 3.23s. I'll bet he can top 19 or 20 with his factory gears and the higher compression.
In reply to Keith Tanner :
If you find any more out there, I'm interested!
I have a 2.94 rear.
I don't really know automatics. What would a low stall TC get me over the switch pitch?
In reply to Keith Tanner :
I'd keep your switch pitch or sell it to me if not. Switch pitch has a low stall and high stall. I had a friend that wired it to a toggle switch and used it as an almost lock up convertor.
Keith Tanner said:I have a 2.94 rear.
I don't really know automatics. What would a low stall TC get me over the switch pitch?
The switch pitch was used in heavy cars to overcome with massive weight and tall rear gears they used. It was a way for manufacturers to keep existing transmissions and gear ratios for MPG, but give a little higher stall for getting moving. This was really slick and helpful with a , or a 307 in a GMC pickup, but behind a big caddy, it is not really necessary. The TC I have will actually stall lower than the lower stall setting on a switch-pitch, so the benefits would be that you can actually use the mountains of torque at 1500 rpms, you would have less heat in the transmission, and you'll have a less-complex setup.
You'll also have a switch-pitch 400 in your shop that might sell for some good cash.
You may already know this part, but in case you don't...
Torque converters are just basically two fans facing each other. You turn on one fan and the other one spins. Its just in this case, they are pushing fluid with really tight tolerances. Think of it like a liquid clutch that always slips a little. Altering the vanes in the pump alters how much slip happens. If you sit in the car and hold your foot on the brake and mash the throttle, the RPMs indicate the stall speed. The stall speed should be matched to the torque peak, so a hopped up high-hp engine needs a higher stall speed. Low-end grunt motors need a lower stall speed. Also important... the same converter will stall at different speeds in different engines. A 2200-rpm stall converter might stall at 1800 behind a V6, and 2400 behind your Caddy.
I would say the big benefits to my converter (and why I spent so much on it) was less heat, better matched to the caddy torque curve, and more efficient on the highway.
So I'd need a new transmission as well? The seller of this engine also has a $100 TH400 with a Chevy bellhousing, but I have no way to evaluate an automatic that's sitting on the floor. We are falling away from the easy option here. I have a known-good transmission in the car and a torque converter that will function with the engine, I think I'll stick with it.
Curtis said:The only BOP-pattern transmissions with a lockup option were the TH350C and THM200C.
There's also the 200-4R. Not sure it would be at all interesting for this thread but it's a POB pattern, has overdrive, and a lockup converter. Someday I'll be able to tell you how it works in my Buick wagon.
In reply to Keith Tanner :
I'm pretty sure you can get a bop adapter for your transmission to the 472. I'll look this evening.
I'll offer you 25% profit and pay shipping for it if you end up not wanting it.
Keith Tanner said:So I'd need a new transmission as well? The seller of this engine also has a $100 TH400 with a Chevy bellhousing, but I have no way to evaluate an automatic that's sitting on the floor. We are falling away from the easy option here. I have a known-good transmission in the car and a torque converter that will function with the engine, I think I'll stick with it.
keep away from scope creep and you'll have a running car sooner..
ClemSparks said:Curtis said:The only BOP-pattern transmissions with a lockup option were the TH350C and THM200C.
There's also the 200-4R. Not sure it would be at all interesting for this thread but it's a POB pattern, has overdrive, and a lockup converter. Someday I'll be able to tell you how it works in my Buick wagon.
Good catch. They can be built to take some torque, but their small diameter clutches are easily overwhelmed.
Fueled by Caffeine said:Keith Tanner said:So I'd need a new transmission as well? The seller of this engine also has a $100 TH400 with a Chevy bellhousing, but I have no way to evaluate an automatic that's sitting on the floor. We are falling away from the easy option here. I have a known-good transmission in the car and a torque converter that will function with the engine, I think I'll stick with it.
keep away from scope creep and you'll have a running car sooner..
I agree. There is a way to convert a switch-pitch to a non-switch but I don't know if its as simple as a valve body swap or if it requires other mods.
However, I will say that BOP TH400s are a dime a dozen. I know of 5 or 6 in the local yard that you could probably drive to test.
Third item down $160
https://www.cad500parts.com/catalog/page29.htm
No need to do anything special to disable switch pitch. Iirc 12v puts it in high stall so no voltage is low stall. If you really want you can put a standard TC in there but save your switch pitch one as they are hard to find.
Isn’t the 200-4R what they run behind black RWD V6 Buicks that lay down sub 10’s on slicks? Should hold up fine to a stockish Cadillac.
I already know about the adapter. That was my plan from the start before you guys started reengineering my transmission :)
In reply to Keith Tanner :
Not me! I'm a big fan of the switch pitch trans. I'd love to put one with a manual valve body behind a high compression 472. I'm actually jelly of you.
Floating Doc said:Vigo said:It would be real hard to lose on this one. It seems a little too good to be true but sometimes just being ready RIGHT NOW with money in hand is all it takes for too good to be true to be true.
You're right. But why do I browse CL when I don't have the money to pay for anything?
That’s how you learn real market prices for things you’re interested in. On the other hand I have stumbled into some really fantastic deals looking at things I can’t afford and then when they pop up free or near free to first person to haul it away.
If it’s wrong then I’m just as guilty.
Keith Tanner said:So I'd need a new transmission as well? The seller of this engine also has a $100 TH400 with a Chevy bellhousing, but I have no way to evaluate an automatic that's sitting on the floor. We are falling away from the easy option here. I have a known-good transmission in the car and a torque converter that will function with the engine, I think I'll stick with it.
You'll need a new transmission anyway. The 429 was used 64-67. Cadillac didn't adopt the BOP pattern until 68 with the 472/500.
Up through 63, they did a "round top" pattern that looked similar to a Buick nailhead. 64-67 was a "flat top" pattern that was still Caddy-only. 68-85 was when they did the BOP pattern.
So, unless your pattern looks like this, you need a new trans anyway. (or an adapter) This is the BOP pattern. Bolts in a relatively straight line with a V-top dip in the bellhousing.
Your bellhousing pattern most likely looks more like this:
A 401 CJ said:Isn’t the 200-4R what they run behind black RWD V6 Buicks that lay down sub 10’s on slicks? Should hold up fine to a stockish Cadillac.
Yes... sub 10s on slicks where the torque peaks at 4500 in a 2800-lb car with 4.10s and $6000 worth of billet transmission parts. Not 550 lb-ft at 1500 rpm in a 4500 lb car with 2.90s. Big difference.
You'll need to log in to post.
