Customs 54 Bel air 350 and transmission swap

I am upgrading to a 350 SBC in my 1954 Bel air.. What transmission would be best to go with. Turbo 350 or a 700r4.. and yes I am swapping out the closed drive line and rearend. Its a cruiser but I still want to be able to drive 70-80 on the highway.

 

700R-4 is pretty big physically and may give you issues with clearance. 200R4 is more on the size of the 350 and used in a lot of similar weight cars
Still there are thousands of Novas, Chevelles and Camaros running around with 350/350 and 2.7 to 3.3 gears.

 

350-350 is easy using all the things made these days to help you out. You will have to rough ups the floor boards if you use the 700.

 

I've changed powerglides to 200R4's, and I really liked it. Got to do the right shift kit, and deal with the lock up converter, but it's more plan ahead than a big deal. The size and weight are right and I like the ratios better than the 7004R. Depends on how bad you want the o/d, new or existing rear end ratio, and your use for the car.

 

TH350 is simple and fine trans.

Leave the 700s for the 4WD crowd. The 1-2 shift drop is comical, drops out of OD under the slightest go pedal pressure, and the no upshift into OD at WOT. It's a fat transmission that needs room.

If you want OD(or just have more gear for fun) use the Th200-4R it's the same length/size as the Th350, uses the same output spline as well(if you swap a Th350 for a Th2004R you just need to move the trans mount back and reverify driveline angles.. Trans mount is in the Th400 position.

 

I had a 350/700R4/ 57 Chevy rear end in my 54 and it was great with 3.55 gears. 3.73 would be ok, too. Do it.

 

Overdrive ............

 

Ok. Thats good to know on the 700

 

My buddy has a 1954 bel air convertible with a 383 and a 700r-4 I dont believe the floor has been modified,I will check.

 

Sorry ,I don't think the car floor was modified, but I will chrck6.

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My car is a 52' BelAir. I'm running a 348 with TH 700r4 and had no problem at all with floorpan........But it may as much to do with how your motor mounts and trans mounts are located as it does the physical size of the transmission. I replaced a TH 475 with the 700r4 and it was a shoe in.

 

Cousin did the 2004r trans in his 54 I believe he has a 354 rear gear does quite nice on the highway. My avatar has the 700 with 373 gears

 

Please do..

 

I just called my buddy that did the change over on the 54 belair,it has a mustang style front end with front air ride,a rack,he is sure he did not modify the floor,stroked 350 (383) and 700r4,he even used the stock powerglide shifter with a overdrive switch on the dash. I have driven the car a lot over the years.

 

Nice! Thats cool being able to use the og shifter. I appreciate it

 

700R4 fits with only very minor mods.

 

I have built several. 3.55 with a 350, 3.73 if keeping the six.

 

That does not exist. Overdrive is not an electrical component on a GM automatic. It is simply 4th gear.

The only electrical control component in a GM overdrive automatic is the lock-up circuit for the torque converter.

To that end, the only time that this should be switched is to disable it, if towing. Otherwise it should be on, and wired through the 4th gear switch inside the transmission, so it automatically locks in 4th.

Leaving it on a manual switch requires that you remember to turn it off, every time you slow down.

Forget once, and you could be explaining your decision to build this way to a cop, judge, insurance adjuster, family of the deceased, your ER doctor, or worse.

 

If you are not already aware of these folks, here you go: https://waltonfab.com/products/

They already worked it all out, so you don't have to.
https://waltonfab.com/product/packa...passenger-car-transmission-and-engine-mounts/

 

I have a 48 Chevy Sedan 350, 700R4 with 3:73 rear. Great combo.


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I advise ones doing a V8 into a 49-54 TO NOT cut off the firewall braces. Just neatly fold them back a bit for rear of head clearance. Now with smooth paved roads one could probably trim them off but back in the day it meant a cracked windshield in time.

 

I have 17 customers with no windshield cracks. Not a one has these braces

7 US states, 3-countries.

The one shown above is in Texas!

 

The ones I been involved with had the braces cut then a weld rod welded over the end. Looked nice and kept the strength.

 

The trans was built by somebody else I don't know how its wired,you could be correct,I drove it many times but always turned the switch of in town we never towed with it

 

Good that.

 

I’d keep it simple with a T350. That cable on the 700r4 if not setup correctly will smoke it in no time. Aftermarket carb levers for the most part are not correct ratio etc. No cable needed with the 350 unless you want kick down.


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Setting up that cable properly, with a helper, takes 90-seconds.

 

True, assuming the lever ratio is correct and the cable doesn’t come loose or the end break off at some point. That’s all it takes and that trans is usually done.


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I have been rebuilding 700R4s since 1985, and I have yet to experience a snapped cable.

Not one, ever.

As for geometry, you buy one small correction bracket, available from numerous vendors, for small money.

There is an inherent danger to misclassification of risk.

You don't hear people running around saying to never bathe, even though you are more likely to slip, fall, and die in the bathroom, than to die from terrorism, by a large percentage.