GoolzCutlass

My 77 cutlass with 350 / 350 Headers and stock 3.42 rear gears. I dont mind the rear gears as they do great on the highway and I have a 29" tall rear tire. I wont be doing the 700r4 swap until next summer. However I am curious about updating my torque converter to get a tad bit more stall. What are the thoughts on the forum about upgrading this for a mostly stock Cutlass. I am thinking 2000 stall. Pros & cons? Thanks

76olds

Stock 3:42 gears in a 77 ?? I'm thinking 2:41 or 2:73 max as stock.
Aside from the that, I put a TCI Saturday night special torque converter in my stock 76 350 with bolt on's such as yours.
Its not worth the $$ or effort IMO, I have a Trans-go shift kit before the T/C swap and pulled a squawk 1-2 shift.
I would just go for a shift kit and leave the stock converter .
Hope this helps!
Eric

GoolzCutlass

My apologies you are correct 76olds they are 2.41. So would just a shift kit alone give me a tad higher / firmer shift? I like the idea of the shift kit being very inexpensive and quick to add. I have springtime plans but still going to drive my 77 plenty in winter. Thanks again for the help.

Fun71

A Trans Go shift kit will give much firmer shifts under full throttle. The shift points are controlled by the governor, so in order to increase the RPM at which the trans shifts you would have to modify the governor, which is a trial and error activity.
What RPM does the trans shift now?
How much higher do you want?

GoolzCutlass

Just a few hundred rpm higher and a bit firmer would be awesome. Seems like a shiftkit would give me that. What are the trans shops charging for this install, I had one put on a different car years ago but had lots of other things done too at that time.

GoolzCutlass

One other thing i am very curious about; does my stock converter for 1977 have lockup? As I read about lockup it peaked my interesest. Ideally I could update my torque converter now to a newer one with lockup and be able to use that same one on a 200r4 or 700r4 when that goes in next year. I think this could be wishful thinking as I dont believe they match up.

olds 307 and 403

You have a non lock up converter. The TH350C lock up converter is different than the early 700R4/2004R lock up converter. Why go 700R4? Much more work than 2004R swap. I say a 2000 stall converter with a governor mod and shift kit will make a difference. This one has the lugs like the stock one.
https://www.summitracing.com/parts/sum-g2699

GoolzCutlass

Thanks 307. The link you provided is to a non lock up converter. Its suprising that i am having trouble finding a lockup converter for my th350 trans. why is that? I see on Summit you can choose for a th350 or th350C, whats the difference? Also if you have a link to the torque converter I am looking for that would be great. Thank you

olds 307 and 403

They don't flip flop, different pumps. Most TH350 converters out there are non lock up, like your trans. The lock up TH350's came out in 1981.

Fun71

A lockup converter mates with a transmission designed for the lockup converter. You can't simply install a lockup converter on a transmission that is not designed for it.

76olds

Yes, a shift kit install with an adjustment at the vacuum modulator with give you a firmer shift.
Have you considered a rear gear/posi swap since your considering the 700r4 or the 200r4.
That's where I would sink some $$ into initially, if your plans are to keep the car and build it a little at a time.

Hope this helps
Eric

olds 307 and 403

Speaking of that, the 2004R is a much easier swap. It might cost slightly more to build but consider cutting the drive shaft and the $100+ cost for the good transmission adapter.

brownbomber77

If you're gonna do it....rear gear first. Then you can feel whether anything else is necessary. A 3.42 will be night and day with that thing. It will make a converter a moot point from how fast you'll be outta the hole and into power.

GoolzCutlass

Thanks guys for all the input. Rear gearing it is! With a 29" rear tire I am now torn between 3.55 and 3.42.

Fun71

I would get whichever is cheaper. I like the 3.55s (had a Chevy 12 bolt with those back in the 80s - loved them!). I have no idea if the two are around the same price or if the 3.55s are more expensive because they are so new.

oldsmobiledave

Put the 3.42s in the car. The difference in acceleration with the 3.55 will be negligible with your engine.

76olds

I went from the 2:41 down to the 3:42 gears in my 76. As others mentioned, huge off the line difference.
If your swapping to the OD Transmission then I would go with 3:73 myself.

Eric

GoolzCutlass

I have access to a posi unit for my rear that has a 3.90 gear in it. would that totally kill any highway driving with my 29" tall back tires?

Fun71

Depends upon how fast you want to drive.

60 MPH would be around 2800 RPM
70 MPH woud be around 3300 RPM

When I had short 245-60-14s my engine spun around 3400 on the highway and I was fine doing road trips. Some folks that are accustomed to modern vehicles with overdrive transmissions totally freak about those RPM levels.

oldsmobiledave

just re-sell the 3.90 gear set or trade it for the 3.42

GoolzCutlass

I'm going to try the 3.90 out. I dont do tons of highway driving. and I want al the other driving to be as fun as hell.

76olds

My 76 with a 3:42 gear + posi + shift kit is more than enough for my style of driving .
If your not concerned with fuel mileage and higher RPM's then go with the 3:90, it may drive you nuts with your TH350 after the increased butt dyno wears off.
Let us know how it works out!
Eric

oldsmobiledave

My 70 W-31 has factory 3.91 gears with the T350. I run 28" tall tires on the car & drive it everywhere...cruises at 3300-3400 rpm and keeps up with traffic just fine.

76olds

Haha ohh, I believe you. I myself can only handle the sound of higher RPM's with headers and duals for so long on a lengthy trip.
The fuel mileage is fair- poor with anything lower than 3:23 with the TH350
Fair with 3:23 then descending the lower you go.

Fun71

Interesting. I don't think the interior noise in my car is any different with headers and performance mufflers than it was with the factory manifolds and whatever exhaust shop mufflers were on it. It is relatively quiet (for a convertible), but my 70 hardtop was similar.

oldsmobiledave

I don't comprehend miles per gallon. Now SMILES per gallon....that I understand

GoolzCutlass

while I was waiting for mu muffler to arrive i already had a 28" glasspack so I thought what the hell and ripped the original exhaust off including the cat and put the glasspack where the cat was. Unbearable drone while accelerating and way too loud for a spaced out neighborhood. It did however sound really good at highway speeds. You can really hear the 350 purr. I now have DynoMax® Ultra Flo™ Welded with H-pipe and they are just too silent. Tempted to buy another glasspack and put two on after the h-pipe. My tailpipes go all the way out the back. We'll see. I'm also one of those who is just not that into the Flowmaster sound.

oldsmobiledave

If the Walkers are too quiet it is not the muffler's fault. You aren't making enough HP to make them sing.

GoolzCutlass

@dave ... Walkers?

oldsmobiledave

Walker...as in Walker Dynomax.

76olds

I have flowmaster super 44's on my 76. I've had many compliments with how good the car sounds given its no muscle car.
However my wife can hear me coming home from about a mile down the road, so it may pi$$ off some if your in a quiet neighbourhood.
If that tone isn't for you, the Hooker Aerochambers or Purple Hornies may be an option over the Dynomax.

midnightleadfoot

I'd go 2200-2500 stall.. remember this is only what it flash to when you hammer it, not what the engine will rpm to ,to get moving..
You are over 2500 rpm when on the hyway so no harm there where the car load of pushing through the air might cause slippage .
and not enough of a load under hyway speeds that the 2500 stall would be an issue..
Now when you go to the 7004r, It'll cruise the hyway under 2500 rpm most likely. and you'll need the lock up clutch in the converter..
IIRC the cheap way to a higher stall is a corvette converter as it stalled higher than lesser cars..
Vega's was another slick way.. but that was years ago. a stock replacement type might be the same money as a tci/huges/b&m one now..