thoughts on C3 automatics
Thread Starter
Intermediate
Joined: Jul 2019
Posts: 48
Likes: 1
thoughts on C3 automatics
Just started researching on C3s, in particular 1970s and 1971s.
I'm planning to get an auto so the Mrs can also drive it. She has no interests in learning to drive stick so that's that.
So thoughts on the stock autos on C3s of this era? I can be convinced to go with later C3s but the chrome bumpers are the bee's knees.
Option 2 is to look for a restomod (I know that's a sore subject for some), it's going to be a driver so reasonable reliability is paramount.
I'm planning to get an auto so the Mrs can also drive it. She has no interests in learning to drive stick so that's that.
So thoughts on the stock autos on C3s of this era? I can be convinced to go with later C3s but the chrome bumpers are the bee's knees.
Option 2 is to look for a restomod (I know that's a sore subject for some), it's going to be a driver so reasonable reliability is paramount.
Drifting
Joined: Jun 2012
Posts: 1,990
Likes: 183
From: Port St. Lucie Fl
stock autos are 3 speeds and result in either low performance off the line or high rpm on the interstate, due to rear diff gears. Going with a resto mod should land you a car with overdrive so you can have off the line performance and cruise the interstate and descent rpms.
Race Director
Joined: Jul 2015
Posts: 13,082
Likes: 3,399
From: SW Florida.
drag strip stay with the T400. street, 2004r or 700r4. PM this guy. he is removing 700r setup and going 5 or 6 speed stick. https://www.corvetteforum.com/forums...uto-trans.html
Last edited by derekderek; Jul 17, 2019 at 10:55 AM.
Drifting
Joined: Nov 2016
Posts: 1,963
Likes: 579
From: Pittsburgh PA
i have 2 68s, one 4 speed L79 other is a base engine auto. I specifically bought the auto so my wife could drive it.
the auto definitely lacks the performance of the L79 stick off the line, but its no slug either. I've got not complaints about it
the auto definitely lacks the performance of the L79 stick off the line, but its no slug either. I've got not complaints about it
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Just look for a '71-72 car which has swapped in an overdrive auto already. I'm sure there are many out there. It will be a more economical vehicle and much more comfortable to drive on the highway. You need to be able to make a good assessment of the 'health' of that overdrive trans when you are in the buying process. 200-4R and 700-R4 transmissions would be the preference. Those have TV cables which must be adjusted properly to prevent internal damage. Do some research on the web to understand how those work.
Doing this will greatly simplify getting the car you want....already in the configuration you need. Swapping out the transmission is NOT a simple task nor an inexpensive one.
P.S. If you are buying a "driver" car, don't get hung-up on the 'originality' issue. It would be meaningless for the car you will be buying.
Doing this will greatly simplify getting the car you want....already in the configuration you need. Swapping out the transmission is NOT a simple task nor an inexpensive one.
P.S. If you are buying a "driver" car, don't get hung-up on the 'originality' issue. It would be meaningless for the car you will be buying.
Last edited by 7T1vette; Jul 17, 2019 at 11:42 AM.
Thread Starter
Intermediate
Joined: Jul 2019
Posts: 48
Likes: 1
Thanks guys, I forgot to mention I'm fairly uneducated when it comes to cars. But luckily the internet sent me here to decipher your code languages:
https://www.chevydiy.com/transmissio...oration-guide/
https://gearstar.com/200-4r-transmis...el-efficiency/
I don't even change my own oil anymore, so no way I'd be able to put in a transmission. It seems like one of those overdrive 4 speeds is better for my purposes. It's got to be capable of driving 200 miles north to the Adirondacks as well as cruising along the GSP down to Cape May on a Thanksgiving weekend.
At my age (50 next year), I'm looking to do less fixing and more driving. Only looking for a weekend driver in decent condition but doesn't need to win shows.
Keep it coming, I love learning about this stuff even though I'm not much of a wrench.
https://www.chevydiy.com/transmissio...oration-guide/
https://gearstar.com/200-4r-transmis...el-efficiency/
I don't even change my own oil anymore, so no way I'd be able to put in a transmission. It seems like one of those overdrive 4 speeds is better for my purposes. It's got to be capable of driving 200 miles north to the Adirondacks as well as cruising along the GSP down to Cape May on a Thanksgiving weekend.
At my age (50 next year), I'm looking to do less fixing and more driving. Only looking for a weekend driver in decent condition but doesn't need to win shows.
Keep it coming, I love learning about this stuff even though I'm not much of a wrench.
Thread Starter
Intermediate
Joined: Jul 2019
Posts: 48
Likes: 1
Just look for a '71-72 car which has swapped in an overdrive auto already. I'm sure there are many out there. It will be a more economical vehicle and much more comfortable to drive on the highway. You need to be able to make a good assessment of the 'health' of that overdrive trans when you are in the buying process. 200-4R and 700-R4 transmissions would be the preference. Those have TV cables which must be adjusted properly to prevent internal damage. Do some research on the web to understand how those work.
Doing this will greatly simplify getting the car you want....already in the configuration you need. Swapping out the transmission is NOT a simple task nor an inexpensive one.
P.S. If you are buying a "driver" car, don't get hung-up on the 'originality' issue. It would be meaningless for the car you will be buying.
Doing this will greatly simplify getting the car you want....already in the configuration you need. Swapping out the transmission is NOT a simple task nor an inexpensive one.
P.S. If you are buying a "driver" car, don't get hung-up on the 'originality' issue. It would be meaningless for the car you will be buying.
Thanks for adding a new term to my vocabulary, TV = throttle valve
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Melting Slicks
Joined: Aug 2004
Posts: 3,151
Likes: 294
From: Opelousas, Lousiana
CI 6-7 & 9 Veteran
I have a 72 automatic and it works fine. Your wife should have no problem as long as the transmission is in good shape and has been maintained. An overdrive would be nice, but it will cruse OK at highway speeds.
Pro
Joined: Mar 2018
Posts: 526
Likes: 113
From: Seattle WA
I owned an 81 auto for a very short period of time. I was prepared to hate it before I ever drove it. I was pleasantly surprised at how well it drove. A perfectly fine/fun cruiser that you could use like a normal car.
Burning Brakes
Joined: Mar 2006
Posts: 829
Likes: 131
From: Spartanburg SC
How many miles will you actually drive a hobby car per year? 2k? How much fuel would you save a year? How much would it cost to convert to a four speed? Probably looking at a ten year payback. It also cost less to rebuild a three speed than a four, five or six speed. The th400 is a fantastic transmission. The one in my 72 has never been out of the car. That is a highly maintained 47 year old trans.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Since the OP is using the car as a "cruiser", rather than a hot rod, it made sense to me to stay away from the high compression, premium-drinking engines of 1970 and earlier. If you can drive on regular fuel, it's less expensive. More money left for FUN!!! 
Thread Starter
Intermediate
Joined: Jul 2019
Posts: 48
Likes: 1
Can the 68-70 before the detuned engines take on the premium gas at the pumps? or are you saying I need to source rocket fuel to fill the tank? My daily drivers are all running on Super so, I'm used to counting Jackson's at the pumps...
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
It depends on the engine and the quality of fuel used from "today's" pumps. 93 octane will usually work OK in 10.5:1 compression engines with iron cylinder heads. But, in hotter environments or if ethanol is mixed in the fuel, those engines might have some spark knock. And in the '68-70 time period, there were some 11:1 compression engines made with iron heads. Unless the owner was willing to 'detune' the engine, those would never run well on premium pump gas.
That's why I limited my recommendations to '71-72 (for chrome bumper car (or '73 for a 1/2 chrome bumper car).
That's why I limited my recommendations to '71-72 (for chrome bumper car (or '73 for a 1/2 chrome bumper car).
