TH 350 w/lockup converter-anyone have any experience with one?

[destinbeachman]

Thinking about going with one.Just rebuilt the big block-went up to a 454 with P&P oval port heads,Lunati Voodoo cam,RPM Airgap,MSD billet,6ALetc. and am already starting to have issues with the stock TH350 with shift kit.I asked the owner of the local shop(full-on place that does everything from grocery getters to quarter-milers,circle track cars and pullin' trucks)about changing the third gear when we build it up so I'll have a bit gearing on the highway and he asked me if I had ever considered a lockup 350.Would probably end up wiring it up to one of the new programmable speedos so it wouldn't be locked up till about 60 or so.Has anyone here ever used one in their truck?Or have first-hand info? -Allen

 

[dyeager535]

Shouldn't be any different than any other GM lockup (namely the 700) except that they predate even that one, and COULD potentially be problematic as a result.

The TH350 was a good tranny, adding lockup shouldn't have made it any less so, but it does add parts and a bit more complexity. As little as these were used though, it doesn't seem many have much experience with them.

I'm a little confused about the third gear comment...you mean as in changing it to get lower RPM's while in 3rd? If you want better trans gearing , I'd suggest biting the bullet and going 700 or 4L80E...the couple hundred RPM drop (at best) from TCC isn't enough IMO to consider adding it, solely for that reason. Better for heat during cruise, but under load it shouldn't be in use anyway, negating *most* heat arguments.

 

[JEBSR]

As long as you don't accelerate it real hard on a regular basis with the converter locked it should ok.

However in my opinion a 350 just isn't strong enough behind that big block. I want a trans that I can run hard and not worry about.

 

[destinbeachman]

I'd rather not go to another tranny type(400,700,etc)if I can help it.I like the way I have her set up now.I don't know how much the motor is putting down but it's pretty d**n healthy.But it's not like 500 HP.Should be more like about 375HP/475lbs.I don't see why I can't run that through a built TH350 without any problems.The one that's in it held up fine behind the mild 427.Anyway,so I'd only get like a 200 rpm drop huh?That's not going to be worth spending the extra bucks.I think we'll just see what the gear is that's in her now(3rd gear)and see what's available and maybe replace it when we build her up.Unless I find another way... That seems to be what we all do on this site-find another way.

 

[JEBSR]

That's understandable, the 3rd gear will be 1:1. Don't get me wrong a good trans builder can make that 350 work nice. I just typically go overkill a to ensure long term I don't spend more than I would have putting something bigger in originally. Good luck with it.