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TH200-4r with my 327

7K views 30 replies 16 participants last post by  von 
#1 ·
I bought my 66 Chevelle with a TH350 transmission behind the original 327, 275 HP. It is leaking a little and also shifts into reverse or drive with a bang from park. The car also rolls in park. I could have it looked at but I have a chance to buy a TH200-4r transmission and torque converter from a 1988 Monte Carlo SS for $300. This would give me an overdrive 4 speed. My rear end is a 3.08 and I'm wondering if that would need to be changed. Looking for opinions from those more experienced than I am. Is this a wise move if I use the new tranny in stock form?
 
#3 ·
rumor has it that 200/350 require same length driveshaft. The 327 might not like 1500-1800 rpm at 70 mph tho. Carb needs more rpm to get off idle circuit to high speed circuit -may cause drivability problem . 3.73 gear will make this a nice combo
 
#4 ·
The 200 4R has a slightly higher (numerically) 1st gear ratio than the TH350 so drivability shouldn't suffer. In OD it would turn pretty low rpms though. A 3.73 would give better acceleration with either trans. A 200 4R from a Monte SS is a good choice. One from any other car besides a Buick GN or Olds 442 would require some work for any kind of performance use. I'd go for it and worry about a rear gear swap later. BTW the shift detents are in the trans so your linkage should work fine. I had to dimple the floor pan in my Malibu to get linkage clearance for manual low gear though.
 
#5 ·
The short (9 inch tail housing) glide was only used on 62, 63, and 64 full size cars (and maybe some truck applications). All other glides used the 12 inch tail housing.
 

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#8 ·
changed a 350 to a 200-R4 in an afternoon in my driveway. Driveshaft works, cooling lines worked, moved the crossmember back, one pair of the holes were already there. Had to drill 2 holes. Shift linkage worked although it's hard to get it into first gear. speedo cable worked.

I went with 3.73 gears, a mistake. 3.36 or 3.42 is where it's at. Need to hook up something for converter lock.

AFAIC, you don't need to buy any expensive aftermarket junk to make this deal work.
 
#9 ·
Need to hook up something for converter lock.

AFAIC, you don't need to buy any expensive aftermarket junk to make this deal work.
S10's and mini Blazers that had lock up converters in the early 80's used a vacuum switch mounted under hood to accomplish converter lock up. No computer was required. The wiring harness hook up's are same configuration as on a normal 200-4.

I paid $ 3.00 for the switch, wiring harness, and vacuum hose at the local pick-a-part. :thumbsup:
 
#10 ·
I have mine running through a toggle switch, brake light switch,& a vacuum switch.
 
#11 ·
One reason I am waiting until fall is because my exhaust on the car now won't allow the cross member to be moved back without modifications so while I could install the tranny in a day or so, I wouldn't have the rear axle gears or the exhaust straightened out. I just got the car so I want to enjoy it this summer and have plenty of other small things to do to it.
 
#12 ·
throttle cable is critical to make shift points , and the life of trans.-basically takes the place of a vacuum modulator. Look for bracket to make this connection at carb.There are a number of aftermarket kits depending on specific carb
 
#14 ·
The Monte SS cars came with 3.73 and the 2004r from the factory and it worked quite well.

I see no issue with 3.73 or 3.42.

I currently have 3.08 and it's way too steep and the shift points are not in a good place - but my th350 trans was blown so I replaced it with a 2004r and the rear gears are coming next (most likely 3.73)
 
#15 ·
I have 3.73 & 28 in. tires seems like a good combo, runs 1950 @ 60 or 3900 @ 120.
 
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#16 ·
Well, I was swapping out an old three speed stick trans in a 57 Chevy 283 that had 4.11's. RPM's were never a problem with the short stroke. I just wanted to be able to hear the radio when I was going down the highway.....
 
#17 ·
I saw on Monster transmission site that they run 12V to the lockup electrical connection and then make ground through a pressure switch (repurposed brake light switch) that is screwed into the 4th gear pressure port on the opposite side of the tranny so you get lockup in 4th gear. It has a toggle switch on the 12V wire so it can be disabled. Easy to do, they get $99 for about $19 worth of hardware.
 
#20 ·
Really nothing special about them, the valve body is the main thing. But it is a very desirable VB. They have a bit bigger servo.
 
#23 ·
I run a 700r4 in one of my cars with a 3.36 gear. With the converter locked I turn around 2200 at 70mph with a 285/40-17 tire. I ended up doing a cam swap because at 70 with the old roller in the car it was still loping a little. Backed down on the duration and went to a 113 lobe center instead of the old 109. Completely changed the car and the fun factor on the highway.
 
#24 ·
I used the same trans in my "74 Malibu and was able to reinstall the drive shaft. We had to move the trans cross member back and reuse the steering column lockout with no issues. I highly recommend the swap but also check your gearing to put the motor in its sweet spot at cruising speed.
 
#25 ·
I recently converted to a 2004R behind a 350 with 3.73 gears. It's great. The cross member mounted to existing holes, used the stock driveshaft. Bought the TV cable kit from Bowtie Overdrives. It's critical to get that right. You have to convert the linkage on the carb, they have kits for Holley, Edelbrock & Rochester. I also bought the pressure gauge to insure the TV cable was set up correctly. I bought the overdrive console kit from Shiftworks. For lock up I use a B&M speed controller, vacuum switch, brake switch and 15 sec timer delay. Work just like a computer controlled transmission. I did have some clearance issues with the exhaust once the trans cross member moved back, I also had issues with the emergency brake cable and bought a TH400 stainless steel e-brake kit.
 
#27 ·
Yep, that's the B&M speed controller. Really helps prevent from locking up in 4th gear doing 40mph. I set mine at about 55. The vacuum switch helps unlock when you're on the highway and going up a slight grade or passing. When you give it some gas and the vacuum drops, unlocks the trans and gives you a few extra rpm, also allows for a smooth shift into 3rd if needed. I installed a timer with the vacuum switch because under certain conditions the vacuum switch would go into this on/off mode as the vacuum would fluctuate when it was on the cusp of the parameters of the switch. On early 700R4's the factory installed a vacuum delay pod, but I couldn't find one that delayed long enough, so I installed a delay-on timer relay.
 
#29 ·
That's about 4500 rpm isn't it? Thought they shifted at about 5500, my CQ shifted at 5300, but I have it up to a bit over 6000 now.
 
#31 ·
For my conv lockup I just use an inexpensive 4th gear pressure switch in the trans. It locks the converter just after the trans shifts to OD 4th gear. I also have the GM cruise control type brake light switch with the lockup power feed wired through it so conv unlocks when brakes are applied. Otherwise when slowing to below OD speed the trans downshifts to 3rd and unlocks the conv. Or in OD and I accelerate enough to downshift to 3rd (far from WOT), it unlocks. Works well for me and didn't cost much.
 
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