Hot Rods TH350 with a Chevy 250

Look on the ac***ulator cover first .First two digits should be the year. Later years, it's on the governor cover.

 

I will look again but I couldn't see any numbers.

 

Here's the set up my buddy went with on his 49 chevy. He used a stock 50 power glide column shifter along with his stock column and he kept his original gear box. Then he ordered a plexigl*** indicator from chevy of the 40s.

 

if you spend some time, you might find casting date symbols on many of the cast aluminum parts. they are hard to read. But the year doesn't matter too much...they were mostly the same till the late 70s, when they made some internal changes, such as changing how the ring gears and hubs work (one piece instead of two pieces), changed some thrust washers, etc. And they started making the lockup torque converter version (TH350C).

 

Thanks Jim.

 

Jim, I looked at the transmission again and the only casting numbers I found were inside the front by the bellhousing. Just in front of the round plate. It looks like GM15 626 something 233, or maybe it's GM15 828 something 233. I say something cause the middle digit I can't read. Perhaps these aren't the numbers at all.

 

The casting dates are little circles, sometimes with three radial lines (like a Mercedes symbol), sometimes with a hex in the middle, there might be numbers like 5 72 and maybe some dots...

they can be very strange things, to try to figure out. I was just looking at an ac***ulator piston on a TH400 I'm working on, it had that 5 72 number I mentioned

I should take some pictures...but its getting late.

 

I found one picture on the internet...

 

Thanks Jim, I will look for it.

 

Jim, I found it. Can you tell me the year or make?

 

I would guess that it's a very early transmission, from the (upside down) 68 code. But I would also look around for other clues, before reaching any conclusions. There might be a casting date on the pump, and on the case, and on some internal parts.

With the amount of dirt on there...it's probably due for a rebuild

 

Thanks

 

So I already know that when buying the torque converter I need to make sure it's for a six not a V8, correct? Cause it's going on my 250. Now as far as the flexplate, how do I know what to buy?

 

you probably want a 153 tooth flexplate. The same one fit for many years, both 6 and V8 engines. you might be able to just look for one that matches what the engine is out of. do you know what the engine is out of?

 

The engine is a 70 camaro.

 

So I'm have a hard time finding a flexplate and torque converter at any of our parts stores. They want more information like what year my th350 is, what it came out of, etc.
I went in there and told them I needed a flexplate for a 70 camaro with the inline six 250 and a th350 transmission. And told them the torque converter needed to be for the inline six not a V8.
Any suggestions?

 

Looks like I may get lucky with the lenght of the th350. It's almost the same lenght, and because my drive shaft had a lot of play, it may fit without having to shorten it. And the splines matched too. The pictured show the th350 on the right.

 

Might be an optical illusion, but it looks to me like you need a short T350 for the driveshaft to interchange.
How about putting like you know, a tape measure on them?

 

I placed the drive shaft in and it connects right in. From what I can see, with the extra room I had before on the drives haft, it should go in with no problem. If not, then I will have to shorten it.

 

I think you'll find that you end up with the same torque converter listed for V8 and six cylinder applications, and it'll work ok. If it were a Powerglide, you'd definitely need the higher stall speed that the 6 cylinder converter would give, but the TH350 has a steeper first gear ratio, so you don't need as much stall speed. (Powerglide and TH350 converters are different, they use different input shaft spline counts)

 

Okay so when I go in to buy one, should I just ask for a converter based on my make, year, and type of motor? And how should I ask for the flexplate? Cause tonight when I tried buying one they couldn't help me because I didn't know the year of the th350 or what it came out of.

 

before you go to the parts store, first look up the parts you need on the internet, and note the application they are for, or just print out the part numbers.

looks like if you specify that 70 Camaro with the six cylinder and automatic, you might find the parts you need. Make sure it's a 153 tooth flexplate (12.85" diameter), and TH350 torque converter (30 spline, not 17). I'm ***uming you have that size flywheel already...if you have a larger diameter flywheel, then you want a larger diameter flexplate...and we can figure out what that would be from. The reason you want to keep the same diameter is so the starter you have now will still work.

 

I forgot to ask, how is your 250 mounted?

The original engine was mounted at the front, and there were side mounts on the bell housing. The torque tube attached to the transmission.

What rear end is in it now?

 

Thanks Squirrel, you have been great with all the info. When I get home from work, I will size my flywheel.

 

My 50 is actually mounted with side mounts. I got them from chasis engeniring.

 

I just got done checking with Napa and one of the guys there happens to be a car guy, old school too. Anyhow, you was able to find me a flexplate for 36 dollars and the torque converter for about 135 or so. I haven't bought them cause I'm going to bring him the flywheel to match with the flexplate.

 

there are two sizes, 14" 168 tooth and 12.8?"153 tooth.

 

Not every vehicle (or owner) needs to fill this role.

 

Hey Squirrel, you know if this torque converter would fit my application? My local parts store is wanting 250 for one. That's 99 for the converter, 25 each way for shipping, and 75 for the core. The rest is tax. I don't know if it's worth it, or if I should order it through rock auto.

 

No. Too much.
Just buy it from Rock Auto. What's the problem?
Where are you located?