jerseyjoe

Anyone have an experience switching around torque converters? Asking b/c my cutlass feels like it should have more power off the line, once it is going it runs well. I switched out my Jetaway for a TH350 trans a little while back. I used the converter that came with the 350. It is a Transtar rebuilt GM3R heavy duty 13 inch converter with a 1300-1500 stall. It is listed under TH400 in their catalog. I am considering trying the 12.5 inch converter from the Jetaway to see if it makes a difference. I know Joe P. mentioned people have used the Jetaway converter successfully but I cannot find any real specs on it. Or should I buy a converter for the 350 with a higher stall speed? The engine is a stock 350 4bbl with factory dual exhaust set up.

Thanks, Joe

oldcutlass

Do you have a tach? Do you know what your current converter is flashing to. What are your engine specs and rear gears?

coppercutlass

I have a 1900-2300 stall I ran in my th400 for only one season. If you are interested i'll sell it to you. This converter behind your 350 will be good. I rant it on a 350 but it was a little too tight for my set up so I went higher stall. This will work for stock to moderate mild engine.

nofiveo

Your post doesn't mention it, but have you swapped out the rear gears yet? I see your sig line mentions a 2.78 gear. I'd bet with a nice 3.42 in there, you'd think it was a different car.

droldsmorland

nofiveo I lived in Holmen for 10 years! Great place!

jerseyjoe if you have a 2 series rear thats part (most) of the problem. If you switched gear sets and step up to a low 3 series 308-342 etc...you will see a difference even with that factory stall converter. For the biggest bang you will need a higher stall converter to go with the gear set say a 2000-2500 or 2500-2700. Gas miles will suffer but who cares right? Try the converter first as its probably easier then setting up and converting the rear to a 3 series.

jerseyjoe

Thanks for the responses, please see below. I am going to try and get in touch with transtar to see if I can get any more details on the one I have.

I don't have a tach in the car but have one I can hook up temporarily. Not sure what current converter is flashing to. Engine is stock from 1968, good compression, no smoke but definitely more of a cruiser.

Thanks coppercutlass, I will definitely let you know if I decide to go that high.

2.78 Posi is still in it. Yeah, the lower gear would be nice!

I know the gears are high, when I saw the posi tag I got excited for a moment, when I found out it was a 2.78 that was the end of the excitement! I know switching carriers to a 3 series can be done, setting it up and cost has it down on the list for now.
I almost put the jetaway converter back in at the time but I only had help long enough to swap trans. I wanted to drain the converter to make sure there was no metal in it. It was clean and quite a bit lighter then the heavy duty one I installed.

jerseyjoe

I spoke with Dave at transtar. Nice guy, good info, the converter in the car is a heavy duty low stall 1300-1500 converter for towing. They also sell a rebuilt converter for the jetaway. The specs he has for it are 1600-1800 stall speed.
Any downside to trying the converter that was on the jetaway?

oldcutlass

I think with the gears you have you would be better with the 16-1800 stall for local driving. 18-2200 would be better. Call a couple of torque converter companies and ask their opinion.

droldsmorland

Get on line with Jegs and get one of the TCI converters. The Saturday Night Specials (4-500 rpm over stock) or Break-Away (1000 over stock). They have a chart right there which shows the combos with what rear gears, stock or modified engines etc...take a look. Prices aren't too bad either. IMO the Saturday Night Special fits your bill with either gear you mentioned.
I'm running a Break-Away converter with a "Street Fighter" TCI TH400 on the street. I have a 308 gear with a 400 big block with 400 Rear Wheel HP. Nice! Roast the tires at will. Real happy with that converter & Trans.
FYI you can use that limited slip 2 series carrier with with a 308-323 gear set. You simply need to purchase a spacer that goes between the carrier and ring gear and longer (ARP) ring gear fasteners. As long as your into the rear that deep replace all the bearings and races with USA made parts. Any of the drive train online vendors should be able to supply the spacer. You need to go directly to ARP for the bolts and hardened washers. I installed ARPs on the carrier caps too. Make sure you know exactly what the diameter is of the ring gear. 8.2 or 8.5".

jerseyjoe

Thanks guys, I will check out Jegs, sounds like what I am looking for...

coppercutlass

I ran the tci Saturday night special and it worked very well.

anthonyP

Hello.

Is the 2.78 posi a 12-bolt, and is it the stock unit from your '68, if not, what year. If you decide to purchase another axle with a lower gear ratio, please let me know how much you would want for the 2.78 axle.

Thanks,
Anthony