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I am in the planning stage of swapping out the 2 speed on my 67 Cutlass to the TH350, this month.
Column shift automatic
330 (low comp) w/a 2 barrel - but I will be swapping out to a new intake and 4 barrel this month too.
Dual exhaust
No A/C
TH-350 (BOP) - 6" tail. Is there any particular year or range of years that I should specify?
Torque Converter (1,400 rpm stall, I think that is what the stock one is?)
Kick down cable and bracket for carb
Speedo gear
Trans fluid filler tube
That's pretty much it. The old cooler lines will bolt right up to the TH350. At worst there might be some minor teaking. The kickdown cable brackets for a 2bbl may be difficult to source, and of course you'll need to add a feature on the carb to connect the cable to.
That's pretty much it. The old cooler lines will bolt right up to the TH350. At worst there might be some minor teaking. The kickdown cable brackets for a 2bbl may be difficult to source, and of course you'll need to add a feature on the carb to connect the cable to.
If I am understanding you correctly, that means that the 4 barrel brackets are easier to get than the 2 barrel ones? Just trying to get my ducks in a row. Thanks!
Where is a good place (online) to buy a reman TH350 BOP, with a warranty? I am having no luck sourcing one locally and I am not interested in buying a core and rebuilding myself. I appreciate the input.
I would pass on the 1400 RPM converter and get one that's 1800-2000. A quality one will work exactly the same during light throttle operation and give better performance at full-throttle.
I would pass on the 1400 RPM converter and get one that's 1800-2000. A quality one will work exactly the same during light throttle operation and give better performance at full-throttle.
Agreed. That’s a pretty tight converter, a 1800 would really wake it up with zero downside.
I would pass on the 1400 RPM converter and get one that's 1800-2000. A quality one will work exactly the same during light throttle operation and give better performance at full-throttle.
Agree, the factory stall around 1600 for what I have seen. A high teens to low 2000 stall will help launch a lot.
Torque Converter - for now, it's whatever the trans that I purchased came with. Since the 2 speed crapped out during "cruising season", I had no choice but to get what I could as soon as I could...she's been in the shop 5 weeks already. If I don't like the way the car runs, I can always swap out the converter during the off-season. Just add that to my growing "To Do" list. LOL
From what I have read, you want the stall to be lower than what your cruise RPM is. Since I haven't been able to put a lot of miles on my car, I believe that my cruise rpm is 2,500 at 70 mph. I will double check that once I am able to get some miles on her.
From what I have read, you want the stall to be lower than what your cruise RPM is.
That's not 100% accurate and depends a lot on the converter design. Poorly designed converters will slip more at highway speeds, whereas better ones will not.
I have a Hughes Performance 2500 RPM converter and it worked very well when I had a 2.56 rearend installed and the cruise RPM was under 1800 RPM. I calculated the same converter slippage (~300 RPM) when driving under 1800 RPM and when at 3200 RPM (with the 3.23 rearend).
Once again, if it’s a quality converter, everyday normal driving you will hardly notice it.
Torque converters are load sensitive. Let’s say a converter has a 3000 stall speed in a big heavy land barge. Take out the torquey big block and put in a rowdy high winding small block, the stall speed will be lower because the engine isn’t capable of providing the same input torque.
Reinstall the big block and put that exact drivetrain in a much lighter car, the converter will have a slightly lower stall speed because the lighter weight vehicle puts less load on the drivetrain. Put that same drivetrain in a motor home, the stall speed will be higher because the heavier vehicle puts more load on the converter.
When converter companies say a converter will have an advertised speed, it’s a calculated guesstimate. It’s worth it to call the company of choice and get a custom built converter. You’re guaranteed to get exactly what you need, They will ask for vehicle weight, gear ratio, tire diameter, engine, camshaft, etc. The money info you can provide, the better they can dial in your ideal converter.
Like I said before, "from what I read..." This is all new to me and an on going education. When I was (much) younger we never dove into torque converter specs, you just slapped in what was available and what you could afford. LOL
I remember the old timers telling me the hot setup was using a Vega converter. Perfect example of more power combined with a heavier vehicle resulting in more stall speed.
While it worked (meaning it definitely had higher stall) the Vega converter was never designed for that application! It worked, just not for long.
UPDATE:
I finally got her back from the trans shop last night. Only got to put on about 30 miles, so far, but I have to tell you that it sure is nice having a working transmission again. LOL
I now have a rebuilt BOP TH-350 with a reman'd torque converter.
If it would STOP raining in Wisconsin, I might be able to put some more miles on the car.
Speedo is way off so the next "rainy day in the garage" I will inspect the speedo gears to see what I have and then I can figure out what I will need. In the meantime, I am using a speedometer app on my phone, which is good enough for now.
UPDATE:
I have the correct speedo gear installed so the speedo is spot on!
We have over 600 miles on the car after the BOP TH350 swap, very happy with the upgrade but it would be nice to have a little more "umph" off of the line - without changing rear gears. If I didn't mention it before, I have the low HP 330 with an Edelbrock Performer intake and AVS-2 carb (650 cfm), 2 1/4" dual exhaust, 275/60-15 tires on the rear and 2:78 gears.
Cruising at 58 mph is at 2,000 rpm and 70 mph is at about 2,600 rpm.
This was us this past weekend at the Iola Car Show in Iola, WI.
Well, there's one more way to get a better launch - a trans with a lower first gear. Your TH350 has a 2.52:1 first. A 200-4R has a 2.74:1 first, which would be equivalent to almost 3.08 rear gears with your current trans. Personally I'd go with 3.23s with the TH350, but that means a different carrier for the rear axle.
Where is the torque converter flashing? Like I said, the factory low stall sucks, something high teens to mid 2000's is night and day different. I put a 2000 to 2200 TH350, with 2.78 gears and the same 275/60R15 tires launch pretty good off the line, just a 9.5 to 1 350 with 204/214 cam, headers with mild iron heads.
Where is the torque converter flashing? Like I said, the factory low stall sucks, something high teens to mid 2000's is night and day different. I put a 2000 to 2200 TH350, with 2.78 gears and the same 275/60R15 tires launch pretty good off the line, just a 9.5 to 1 350 with 204/214 cam, headers with mild iron heads.
I was thinking about a different torque converter too - I have a factory stall in it now. Off season I will be pulling the engine and trans to do some detail work on them and the engine bay and thought that would be the ideal time to either upgrade the torque converter or switch to an overdrive trans.
Well, there's one more way to get a better launch - a trans with a lower first gear. Your TH350 has a 2.52:1 first. A 200-4R has a 2.74:1 first, which would be equivalent to almost 3.08 rear gears with your current trans. Personally I'd go with 3.23s with the TH350, but that means a different carrier for the rear axle.
Yup, I was thinking about the 200-4R as a possible off-season swap or the torque converter or both. The OD trans would be nice for highway cruising though. Thankfully there are a few more months of good weather in WI to ponder these before making my off-season "wish list".
I reached out to Hughes Performance yesterday with the specs on my car and they came back with recommending their GM11TOW converter. The Tech stated; "These are our HD tow series units that provide about 300 RPM more stall than stock."
According to their website, it is a Tow Master 1800 - 2000. And the description states; "Our severe duty performance converter used in many late model trucks, crew cabs, 4x4's and motor homes will increase bottom end pulling power without sacrificing top end efficiency or lock-up. Mileage is increased by as much as 1-2 miles per gallon. Recommended for slightly modified engines."
No, I did not buy it already. LOL I am continuing my education as the year goes on.
