When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
my 67 has 3.23 th400 over drive. I've a 455 from a 71 in it mild cam, stock G heads, edelbrock torquer intake and a aed 750 carb with some long tube headers more junk inside the engine but i cruise to work daily in it 65 mph in O.D. at 1850ish rpm. I've no clue how much power it has never dynoed but if i step on it I'm close to doing a wheelie. i don't see how/why these other guys let their engines spin over 3k often unless their racing
Last edited by Brutalbeast67; Mar 30, 2021 at 11:02 AM.
Reason: typos
The TH400 doesn't have overdrive. If he added a Gear Vendors OD unit which has a 0.78 OD, the math is pretty close.
I'm curious why spinning the engine over 3,000 rpm is a bad thing? I've only been to the track a few times, but beat it like a rental mule regularly on the street.
For me to cruise with traffic on the highway (80+ mph) I'm around 2,800rpm. 3.91 gears with a 0.67 overdrive.
There is nothing wrong with the engine spinning that fast. People drove cars like this for decades without any problems. Usual gear ratios were 3.08, 3.42, 3.55, then the performance gear ratios of 3.73 and 4.10s were pretty common.
People didn’t know any different until overdrive transmissions became common. Once people got use to 1800-2200 cruise rpm, then suddenly anything 2800 or more was unreasonable. Then throw in inaccurate speedometer and tachometers, that really raises people’s blood pressure.
Hey Brutalbeast, tell me more about installing the G/V unit. What did you do for a crossmember? How did you wire it up? Have you had any trouble with it? Is it as great as advertised? I've been considering one and want some real world experience from an owner.
I went from 2.56's to 3.23's with an Eaton posi in my 75. The difference is amazing although I wish I had went with the 3.08's. I'm turning 3000 rpm at 70 mph with a 255/60-15 rear tire.
OD transmissions didn't come about to reduce wear on the engine (although this is a beneficial side effect), it was to increase MPGs on the highway by reducing friction and pumping losses (just as a taller rear gear does).
Hey Brutalbeast, tell me more about installing the G/V unit. What did you do for a crossmember? How did you wire it up? Have you had any trouble with it? Is it as great as advertised? I've been considering one and want some real world experience from an owner.
I installed a gear vender in my 69 years ago. The my car had the stamped steel trans crossmember. While that style is basically a bolt in, it’s not easy to work around. I later modified a Chevelle style crossmember as per the gear vender instructions. It’s much easier to get in or out of the car.
None of the crossmember hassles are a result of the gear vender, but because of the big exhaust I have on the car.
If I had to do the overdrive swap today, I would have gone with a 4L80 without hesitation. The lockup converter would be nice, the ability to program shift points would be a huge benefit. The cost of converters and trans controllers has come way down since I did the gear vender.
I didn’t “need” to take it in and out. I have some friends that build custom torque converters. I tried a bunch of different converters in my car, one summer I had 11 different converters just to gather information. I had a data logger installed at the time to record driveshaft rpm and different parameters. At the time (probably 10 years ago) that data logger was state of the art. Now some of the aftermarket EFI systems will record that stuff assuming you buy the sensors.
With the Chevelle crossmember, it took longer to get the car up on the car stands than it did to swap converters. The Chevelle crossmember basically falls out, the original stamped steel part required unhooking the exhaust snd finding just the right angle for it to slip out of the frame.
WOW, Matt! Eleven times? I'll bet the bolt heads were round!
How did your hands hold up? I'm not sure how easy it will be
to find one of those crossmembers, but I'll remember what you
said. Would you want to build up a 4L80 for your sled and sell
me the G/V unit?
I dont think running at 3k rpms on the highway is bad, but better mileage, quieter, ~1k less revs per minute, less heat dissipation required (and probably other things too), those are all good. OD is great and someday will be in my car but for now 3k @70 mph it is
That was 11 times over the entire summer, and back when crawling around on the garage floor didn’t hurt nearly as much as today!!
Unless you already have a transmission and a converter your happy with now, you would be money ahead to skip the gear vender. If you need to build or buy a transmission, and a converter, and the gear vender to go with it, you would spend far more than just doing a 4L80 from the start.
I went from 2.56's to 3.23's with an Eaton posi in my 75. The difference is amazing although I wish I had went with the 3.08's. I'm turning 3000 rpm at 70 mph with a 255/60-15 rear tire.
I'm getting calculated RPM differences of only about 130 rpm. Tachs aren't always accurate, and non-lockup automatic transmissions slip so you may pick up the 100 rpm there you are indicating.
Actually stock to stock, non lock up converters add 250 to 300 rpm, I have never seen 100 rpm on multiple vehicles, stock and aftermarket converters. Oldsmobile's can and did go 3000+ rpm on the highway when these cars were new. Ah single digit fuel economy must have been awesome, then the gas crisis hit and the awesome 60's/early 70's were being given away. They were still cheap till 1990 here, not long after $$$$. You can't compare modern 4 cyl and 6 cyl to our Olds V8, the 455 especially totally different animals. Rev a 403 or 455 drive multiple hours at 3500 rpm in hot weather on a 50 year car, see how it does. Watch the temp gauge climb and the oil pressure drop. My Challenger V6 happily revs to it's 7K redline, maintains good oil pressure with 5W20, goes 10,000 KM between oil changes with modern synthetic oil and the 8 speed with 29.1" modern tire sizes runs at 1400 rpm at 60 mph! It will run 14's in the 1/4 and gets 35+ Imperial MPG at 70 mph! Anyone who compares a 50 year old worn out car to a modern car should have their head examined. I plan on running a slightly modified TH400 with 2.78 gears and 275/60R15 tires for the short term. Even that means 2300 rpm at 60 mph and 2600 rpm at 70 mph. Do you know how far apart gas stations are here in Saskatchewan, single digit mileage would be touch and go in some areas here. A TH2004R which needs $1000 US in parts plus many hours to build along with 3.90 gears in the Type O, another $1000 US with more time, will run at lower rpm thanks to the .67 OD and the 300 rpm a lock up converter drops rpm. Talking 1900 rpm at 60 mph and 2300 at 70 mph, this is my long term plan. Yes, we are spoiled by new cars but unfortunately they have set a bench mark our old cars are now compared to. If you love watching gauges and turning up the radio to drown out the noise, put in 5.00 gears and go cruising
Last edited by olds 307 and 403; Apr 7, 2021 at 06:07 AM.
Nobody put too much concern into fuel economy when these cars were new. Gas was dirt cheap, and cars were much cheaper then. Adjusted for inflation, a well optioned new car in 1970 is cheaper than a stripped down car today. I base this statement on comparing the base price of a 1970 Eldorado (probably one of the most expensive cars from the Big 3) was 5800 (about 38000 today adjusted for inflation). The average cost of a new car today is around 38000 bucks. Of course, most of the luxury items in a Eldorado are standard today, so once again, no way to really compare.
While I wasn’t driving when these cars were new, I have been around them my entire life. Properly tuned and maintained, there is no reason for single digit fuel economy for the vast majority of the cars built then. For every one Hemi Charger with factory 4:10 gears and the dual carbs, there were 1000s of “civilian” 2 bbl small block cars.
I’m sure the vast majority of passenger cars came with gear ratios in the 3.08-3.42 or higher. Combine that with properly tuned engine, you have to be either foot to the floor all the time type of driver, or leaking fuel to not be able to achieve at least 10 miles to the gallon. Seriously, how much power does it really take to maintain a speed of 65mph? Just for discussion, let’s say 75hp. How much fuel does it really take for a properly tuned engine to make that 75hp?
The people who complain about lousy fuel economy either don’t know how to tune a engine, have some seriously mismatched parts, poorly maintained vehicles, inaccurate speedometers, or a combination of all.
Having said all that, obviously you can’t compare today’s cars to the cars of 50 years ago. I have no idea what 35 Imperial actually is when converted to mpg. Safe to say, overdrive transmissions, variable engine displacement, better aerodynamics,and countless other advances from 50 years of innovation have a huge influence on economy.
BTW, wouldn’t the Imperial method of calculating economy be measure in Kilometers per liter? With the possible exception of the 9mm bullet, it’s safe to say Americans aren’t particularly fond of the metric system. Yet I always hear or read people in other countries who do use the metric system referring to fuel economy in Imperil mpg. Just a random thought.
Last edited by matt69olds; Apr 7, 2021 at 07:45 AM.
Th350 , 4500 stall I'm constantly over 3k on the highway. Speedometer has been broken for 10 years lol. Street strip car. With the 350 olds atleast the engine cruises effortlessly at that rpm and actually seems to be very happy. Back when it was a low 12 sec car and I drove it to the track ., I would run a bracket race then drive it home hauling Azzz after a long day.
Actually stock to stock, non lock up converters add 250 to 300 rpm, I have never seen 100 rpm on multiple vehicles, stock and aftermarket converters. Oldsmobile's can and did go 3000+ rpm on the highway when these cars were new. Ah single digit fuel economy must have been awesome, then the gas crisis hit and the awesome 60's/early 70's were being given away. They were still cheap till 1990 here, not long after $$$$. You can't compare modern 4 cyl and 6 cyl to our Olds V8, the 455 especially totally different animals. Rev a 403 or 455 drive multiple hours at 3500 rpm in hot weather on a 50 year car, see how it does. Watch the temp gauge climb and the oil pressure drop. My Challenger V6 happily revs to it's 7K redline, maintains good oil pressure with 5W20, goes 10,000 KM between oil changes with modern synthetic oil and the 8 speed with 29.1" modern tire sizes runs at 1400 rpm at 60 mph! It will run 14's in the 1/4 and gets 35+ Imperial MPG at 70 mph! Anyone who compares a 50 year old worn out car to a modern car should have their head examined. I plan on running a slightly modified TH400 with 2.78 gears and 275/60R15 tires for the short term. Even that means 2300 rpm at 60 mph and 2600 rpm at 70 mph. Do you know how far apart gas stations are here in Saskatchewan, single digit mileage would be touch and go in some areas here. A TH2004R which needs $1000 US in parts plus many hours to build along with 3.90 gears in the Type O, another $1000 US with more time, will run at lower rpm thanks to the .67 OD and the 300 rpm a lock up converter drops rpm. Talking 1900 rpm at 60 mph and 2300 at 70 mph, this is my long term plan. Yes, we are spoiled by new cars but unfortunately they have set a bench mark our old cars are now compared to. If you love watching gauges and turning up the radio to drown out the noise, put in 5.00 gears and go cruising
My point was that 3.08 to 3.23 is not a big enough difference to care about.
Agree, the rpm difference for those gears can be made up with a taller tire. Yeah, gas and cars were cheaper then for sure. The 70's stuff, got bigger, more choked and everything had 2 something gearing. Olds were some of the better ones for fuel economy through the years. Copper's car proves even with old school upgrades the 350 can take high rpms consistently. There are quite a few 455 guys on here who complain of high temps if they go over 55 where the rpms start climbing. Again 50 year old cars.
Being Canadian, we are part of the British Commonwealth, we use Imperial gallons, larger than US gallons. We converted to the Metric system in the 70's. My parents used the British system and I learned the Metric system in school. I use a blend of the two. Basically Imperial gallons are 4.5L compared to 4L for a US gallon. Our mpg is a couple higher than US mpg. Hopefully I see high teens Imperial mpg with my car on the highway
I think the same could be said for the earlier 400's. I think the long rod combo of the common 455 and later 400's and keeping emissions down meant more time for heat to build up. Just a thought. The 425's seem to also not be a victim of the running hot issue.
Being Canadian, we are part of the British Commonwealth, we use Imperial gallons, larger than US gallons. We converted to the Metric system in the 70's. My parents used the British system and I learned the Metric system in school. I use a blend of the two. Basically Imperial gallons are 4.5L compared to 4L for a US gallon. Our mpg is a couple higher than US mpg. Hopefully I see high teens Imperial mpg with my car on the highway
Ok, thanks for the clarification. I thought Imperial was another word for metric. Just another dumb American ignorant about life outside of this country! Learned something new.
I don't know if you American's did it to differ yourselves from England, not sure. Canada signed a piece of paper for Independence. That is why Queen Elizabeth 2 is our monarchy and on our money. Of course with Mom's, Dad's family being Irish from the South and my 4x Great Uncle, Dr John Rae not being Knighted when he should of been, the Royal family aren't exactly my heroes. My Grandfather would take Mom and leave when God save the King played. We sang God save our Queen in Elementary School. Oh, yeah the actual topic😊. Running at 3000 to 3500 rpm driving my Olds to see my Sister 6 hours drive as an example, one way would not be enjoyable. The noise, single digit mpg, along with building heat and dropping oil pressure, isn't my cup of tea. At the end of that drive is the City of Winnipeg traffic. Like I said, each to their own and I get some guys like these cars 100% old school without the fancy OD transmissions.
Raising temperature to the point of too hot, and dropping oil pressure, aint a problem of your end gear ratio, its a mechanical problem due to neglet or failure.
When these cars were new, they were designed to it.
Its amazing how much money and effort people are willing to spend to walk around an clear issue to "band-aid" and dodge fixing the cause.
What year is your Kia to run 60 mph at 4000 rpm? My Daughter's 96 Trecel old Tercel ran around 3300 at 60 mph, 3850 at 70 mph. No tach, supposedly 3.72 gears with 155/80R13 tires. It made it over 400,000 km but a tiny 1.5 EFI motor in a 2000 pound car. Very few of the 3.91 geared cars seem to have their original motor, hmm I wonder why? Not only that, regular motors back then didn't run 300,000 Km, let alone 500,000+ Km modern motors can run. Plus if you are spending 15 K on nice Classic car, why not spend $2500 more and get a near stock TH2004R or 4L80E? If manuals is your game, modern high strength 5 and 6 spd are also available for around the same. Unless it is a special car, especially if you are rebuilding an old 3 spd auto, why not put a high strength OD in its place? Everything needs to be in very good shape to see consistent high rpm. Fine if you put 100 miles on your car, cruising on Weekends. I want to be able to drive my Olds to Niagra Falls, that is 25 hours away BTW. Why would I want a motor I am spending 7K on to last 100,000 Km? Like I said, have at it, if a screaming motor going slow down the highway is your game. No one drives 55 here, except the elderly.
Raising temperature to the point of too hot, and dropping oil pressure, aint a problem of your end gear ratio, its a mechanical problem due to neglet or failure.
When these cars were new, they were designed to it.
Its amazing how much money and effort people are willing to spend to walk around an clear issue to "band-aid" and dodge fixing the cause.
I agree, these cars ran just fine with 3 speed transmissions. It wasn’t uncommon to have 3.73,3.91, or 4.10 gears, you could get deeper gears dealers installed. Properly assembled, and properly maintained, there is ZERO reason these cars can’t do it now. People are spoiled with the taller gears and modern overdrive transmissions of today’s cars.
Are you trying to baffle us with BS?
What it has to do what year the KIA is?
I get it that people want to upgrade their cars in a way or another, but selling it to yourself and others by telling your car wouldnt otherwise survive, is bullshit. Fix it first.
I also want to drive to hungary, its a 1000mile one-way trip ( under 24 hours drive), and i dont see any reason to not drive it at car cruising at 3000rpm. Last time i went there i had also car reving 3000+rpm at cruise, no single hicup. How does it starve you if engine spins 3000rpm?
By the way, we dont either drive 55mph, my car spends mile-wise most at highways, where 75mph is speed-limit, and 85-90mph is normal driving speed. Cutlass drives happily there, and gets double-digits doing it. Revs aint the end-of-all, get over that myth. Temp dont raise over 185F, and oil-pressure keeps on steady 50-55psi with 5w-40 synthetic oil.
Once again i suggest you to experience first-hand the stories your spewing, instead of reading them from someone and then spreading the word as a second bible.
Originally Posted by olds 307 and 403
What year is your Kia to run 60 mph at 4000 rpm? My Daughter's 96 Trecel old Tercel ran around 3300 at 60 mph, 3850 at 70 mph. No tach, supposedly 3.72 gears with 155/80R13 tires. It made it over 400,000 km but a tiny 1.5 EFI motor in a 2000 pound car. Very few of the 3.91 geared cars seem to have their original motor, hmm I wonder why? Not only that, regular motors back then didn't run 300,000 Km, let alone 500,000+ Km modern motors can run. Plus if you are spending 15 K on nice Classic car, why not spend $2500 more and get a near stock TH2004R or 4L80E? If manuals is your game, modern high strength 5 and 6 spd are also available for around the same. Unless it is a special car, especially if you are rebuilding an old 3 spd auto, why not put a high strength OD in its place? Everything needs to be in very good shape to see consistent high rpm. Fine if you put 100 miles on your car, cruising on Weekends. I want to be able to drive my Olds to Niagra Falls, that is 25 hours away BTW. Why would I want a motor I am spending 7K on to last 100,000 Km? Like I said, have at it, if a screaming motor going slow down the highway is your game. No one drives 55 here, except the elderly.
YOU compared these cars to your KIA, are you that stupid to think they are the same? You have made multiple ridiculous statements like this, yet you are the expert. Yes, they will survive IF the heavy duty cooling system they were equipped with is intact and functioning near perfect. A lot of guys in Southern states have cooling issues with these cars, especially with the 455 after gear changes. The majority of these cars came with 2.56 or 2.78 gears, ever wonder why? Drive a modern car, not a **** box, you will see the difference. Sorry, some of us agree with the original poster, KIA comparisons won't change our minds. Yes, I have drove these cars without OD, not much fun.
Last edited by olds 307 and 403; Apr 9, 2021 at 06:03 AM.
Another argument for the deep gears won’t hurt anything:
Automakers build cars, that’s how they make their money. They aren’t going to build a car that is going to cause them additional expenses in warranty or customer satisfaction. That’s why if you read the fine print on the order sheets, there will be little notes saying the 5.13 gears aren’t available with A/C, or 3.91 gears require heavy duty cooling, that rowdy solid lifter cam can’t be ordered with power brakes, or countless other notables. As much as we all like to brag about how hard we beat up on our cars, it’s NOTHING compared to the torture testing and abuse the engineers inflict on a car before production. If there is any doubt something isn’t 100% reliable, it isn’t offered, or if it is, it will have no warranty.
In other words, a car with 3.73 gears, A/C, big block etc, would be offered for sale in Death Valley, no questions asked. If it worked then, but not now, chances are good something has been modified or screws up over the last 50 years.
YOU compared these cars to your KIA, are you that stupid to think they are the same? You have made multiple ridiculous statements like this, yet you are the expert. Yes, they will survive IF the heavy duty cooling system they were equipped with is intact and functioning near perfect. A lot of guys in Southern states have cooling issues with these cars, especially with the 455 after gear changes. The majority of these cars came with 2.56 or 2.78 gears, ever wonder why? Drive a modern car, not a **** box, you will see the difference. Sorry, some of us agree with the original poster, KIA comparisons won't change our minds. Yes, I have drove these cars without OD, not much fun.
Not sure what part you missed that i drive Cutlass happily at 85-90mph at +3000rpm. Not my problem thought. Plus they offered them from the factory that way, warrantied.
If you cant figure out why your pinch-nuts at rocker studs keep walking out even you loctited them, i suggest spending a hour or two with something mechanical.
I can lend the hand that it probably needs rebuild sooner than engine revving a little less, but its not a major problem.
?
