Hey guys, should I expect any issues swapping out my Turbo 350 for a 2004r in my 79? Not looking for opinions on the 200 4r, just any issues I might run into doing the swap. Thanks!

 

I am getting ready to do the same swap and the only thing that I have to LEARN about is the converter lock up. SOme use a switch and I have seen some mods to the trans itself so that it does everything internally via pressure switch. But Size wise everything is the same from trans mount to yoke. Good luck

 

This is my next mod so I'm hanging out.

 

fairly straight forward swap,

get the correct gate for the shifter and the correct bracket for the carb for the detent cable and your good to go

Neal

 

The short answer is no, you shouldn't have any problems. There are a number of things that you'll have to change to make it work properly though.

Assuming that your engine is stock, I wouldn't worry too much about getting the 200 4R modified or strengthened. Same with the torque converter. You'll probably be happier with a stock one fron a Grand National but without a lot of extra HP, you'll likely be thrilled with any stock converter.

Your stock ATF cooling lines and cooler will work with the 2004R. I added a new fluid cooler and ended up changing the lines because they had been so mangled at the transmission by previous removals and installations.

The stock dipstick worked well when I did the swap in my 81. Just didn't seem to fit right in my 73 so I went with a Lokar part.

Although you can make your stock cross member work, I think the aftermarket ones work better and are a lot lighter. Fit better too. Look at Bowtie Overdrives, among others.

The one real addition that you'll have to make is the TV cable. Have a look at the bowtie site for a really good description of how it works and what it's for. The bracket at the carb on my 81 worked perfectly. I had to add one on my 73. No idea of which will be the case on your 79.

There are a number of brackets and details that you can do without or modify existing ones, but in the end, I spent the extra $100 and bought them from a vendor in a kit. I'll have to try to remember the name of the company.

Lastly, if you are going to do the installation yourself, you need to think about how and where you'll do it. I did both of my swaps in a driveway on axle stands. It worked but I didn't enjoy it. These things are pretty heavy and not easy to maneuver from underneath. I bought a cheap transmission jack (scissor type) from Harbor Freight which helped but made me triple check that my life insurance policy was up to date. Cheap tools don't inspire confidence

It isn't a quick job but it's the single best mod I ever did to my cars. No regrets at all.

 

Found it! See kit SC2403.

http://www.shiftworks.com/corvette-68-81.htm

 

What CA-Legal said, he pretty much covered it. I have done a few of these, you can do it on the cheap or buy a bunch of parts, either way will work. Get the tv cable set up right of get ready to burn it up, can't stress this enough.

 

I have 12" lock-up converter. rated 2500 stall. Built by Level 10 Performance. It's about 10 years old now but it only has about 4k miles on it. was in my 86 Grand National. Let me know if interested.

 

The TV cable and lockup are so critically important, though so make sure to focus time and effort there; doing it wrong == dead transmission. Bowtie Overdrive has done a great job getting the cable angle and tension right to make it pretty easy to do it right.


I talked to the folks at Bowtie and they said that essentially that although some people on the interwebs just flip the stock cross member over that it changes the drive shaft angle if you don't make other modifications and that you're better off buying their cross member to get the angle right. (But of course they're trying to sell more cross members.)


I was very close to a 200r4 swap but the importance of getting the TV Cable right and flashbacks to my own lockup torque converter issues with my very first car ever at 16 (87 Montecarlo with a 305 and a 700r4- burnt up the transmission in under a month with no lockup cable- still hear about it twice a year from my dad almost 20 years later; lol!) caused me to run away from my own personal TV cable and TC locking nightmare.

Lost of people love it and I think it's a pretty great idea. For me personally given my disdain for analog technology, fear of burning up another trans, and understanding that the history of Corvette transmissions was TH350- 700r4 - 4L60e (I lose the history there; lol), I really wanted to go the 4L60e route. It's DEFINITELY more expensive requiring a $450 computer controller, but then I get to play with the controller and don't have to worry about analog solutions that tend to not like me.


Adam

 

That's it. It's pretty slick; I like that it even comes with a replacement indicator plate so it appears like it came from the factory with a 4 speed auto; I appreciate those little touches.


Adam

 

Just got mine back on the road last week from doing this swap. On my '77 I just needed to remove the 350 mounting "tab" and the mounting bolts for the 200 4R lined right up. No modification to the cross member needed. I used large jack stands and it was high enough. It is not the most pleasant thing to do but not that hard.

One thing to remember when putting it back in is that the engine is tilted down. Therefore, the tranny needs to be tilted about the same to mate back up. We struggled a bit until we remembered that and then it went right together.

I have a Demon carb and tried using the original 350 kick down bracket and it worked, but I decided to get the correct bracket and it does shift better now.

Don't get too intimidated about the TV setup. Although absolutely critical for correct performance, it is not that hard to adjust. Follow the simple instructions with the TV cable and you will be very close. I then moved the adjustment in and out in very small increments to see what it did to the shift points. It shifts good now. I bet I am back to very close to where it was on the initial setup.

I installed a non lock out unit so I can't comment on the lockout wiring; which, to be honest, sounded like more of a pain than it was worth. To each their own! I have no lugging with 3.08 gears. I run about 2,000 at 70 mph.

Good luck. Great modification!

Cheers
Brad

 

I bought the detent for the shifter and spent some time changing out that piece. The '79 crossmember works just fine, back of the trans bolts to the holes on the back, no mods necessary. You lose an exhaust bracket that normally attaches to the top of the crossmember, but I centered the exhaust pipe in the hole of the crossmember and tightened the clamps on the pipe to hold it where it won't bang on crossmember. Someone makes a bracket for the pipe if you need it, have to look up the vendor. If you can, raise the trans with the dipstick tube on, or in the general vicinity of being on. I had a heck of a time getting the tube on once trans was in.

 

Not getting into the lock up or not lock up thing, have most of you used a STOCK converter with a stall speed of between 1500-1800, or more? Thanks.

 

Mine currently has the stock converter from the 83 caddy that the trans came from, stall is around 1800. i have another trans with a D5 converter that should stall 2000 when I change it out.

 

I just finished the same swap on my 77. The stock crossmember worked fine, just pull off the Turbo 350 extension bracket and you're good to go. My tranny was from Monster Transmission so I used their lockup switch kit and dipstick tube. Bowtie Overdrives is the place to go to for the TV cable carb linkage. My quadrajet didn't match up to either of their kits, but for $80 they set it up custom for me and it works great. Don't mess around here, if you screw up the TV cable it can cost you a tranny. Finally, this is a great time to consider a gear swap. Since I now have a 4th gear, I was able to dump the 3:08's for 3:70's....very nice!

 

If you are doing a used 2004r check the stator support for wear. I used a core with an AA code from a Cadillac in mine. I replaced the stator support, and sun shell with hardened pieces during the overhaul.

Also for the TV cable and setup you might want to check out www.tvmadeez.com some good explanation for how it works and what it needs to do to be setup up correctly.

 

My only real issue was that I had to dimple the exhaust to clear the right rear corner of the tranny pan. The stock crossmember worked fine. Since I have the extra gear now, I took the time to swap out the 3:08 gears for 3:70. With lockup, it's only turning about 2500 on the highway at 70with the 3:70's, compared to close to 3000rpm with the t350 and 3:08's.

 

I'm in the final stages of this swap on my '77.
I went with the tubular cross member from Bow Tie Overdrives because my original was mangled from a previous owner's "off-road excursion".


I've done 100% of the work by myself in 1 to 2 hour bursts with the car on jack stands.
The swap has been remarkably easy -
Bending the existing trans cooler lines to mate up with the 200-4R fittings was the only tricky item. I did it while lying on my back working overhead with a tubing bender.

 

You realize this thread is over a year old. 🤔