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Discussion Starter #1 (Edited)
I'm thinking of adding a stall to my th400. Engine is an Pontiac 350, 040" over, 9:1 compression, with a 270/276 212/220 @0.050" 0.440"/0.450" cam. The rear gears are 2.78:1. The manifold vacuum is 14.5inhg at 650rpm in drive.

I feel like the engine lugs up hills at slower speeds and I feel like I just dont get off the line performance like it should. The most apparent thing to me to help this is gear ratio and stall speed. Overhauling the rear end is a little too much for the current budget, but a stall converter is more practical.

TCI recommended a 2000rpm stall. I'm curious what the stock stall speed is for a th400 that orginally came with a 350 2barrel? 2000rpm stall seems decent for my gears and goal for the car. I hope to have a cruiser that still has good acceleration. My only concern is if a 2000rpm stall would even be that much of a change to warrant the new stall.
 

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Stock stall is around 1800 RPM's, so 2000 RPM's would be a waste of money in my opinion.

I would go with a 2500 RPM stall, but what is called a "tight" converter versus a "loose" converter for street application. You won't get a lot of slip with normal/moderate driving, but it will do its thing when you hit the gas.

I am also going to say your cam is a little too big on duration for the 9.1 compression and 350 cubes. You are giving up engine bottom end right from the get-go and my guess is that it picks up in the mid-to-upper RPM's. So the cam plus the 2.78 gearing is a double negative for any kind of low end performance.

That said, the 2500RPM converter will better match the cam and put the engine into the cam's better power range.

Do you still use the 2 Bbl carb? I can't recall what you had, but wasn't it a 4-Bbl? You want to get air/fuel velocity up to get the engine to respond. Too big of a carb and wrong intake choice will also kill the bottom end. For your application, you definitely want a 180 factory style intake, not an open plenum 360 design. I believe the Edlebrock Performer has a slightly smaller intake runner size than the other intakes. The smaller runners will develop higher velocity of the air/fuel mixture for a more responsive engine feel. The Q-jet with its small primaries and large vacuum secondaries is why they make a good choice. But, if you go Edlebrock AFB, no bigger than 600 CFM.
 

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Discussion Starter #3
I currently have a QJet, rebuilt using cliffs book, suggestions, and parts. I also am using a stock 4barrel manifold.

I realize a little is left on the table with the cam combo and compression. I didnt want to leave anything on table, otherwise I would have just picked up a stock used engine. Just trying to see if there anything I can do to reasonably have the most of both worlds.

You are right on, the car really wakes up around 2500rpm. I wish there was a way to use the 2 series carrier to get 3.42 or 3.55 rear gears..
 

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Go with the converter for now. My '73 Fury has the low 8.4 compression 2 bbl 360 and 2.76 gears. With the 360CI option, the factory stall converter is 2,500 RPM's. Other engine combo's used the 2,000 stall converter. As heavy as that land barge is, you would be surprised how peppy it takes off from a red light with the converter and the 2.76 gearing. The only complaint is that it is a "loose" converter so I have to give it gas to get the engine to rev a bit to get the car rolling on inclines or hills. A "tight" 2,500 stall will be what I go with when I do a rebuild on the engine. I like the 2,500 stall and the 2.76 gears as I can cruise at 70-80 MPH with ease and the car isn't even breathing hard. At 100 MPH, still plenty of pedal left, but not enough balls left to push it any higher - at least until I get the sway bars and HD torsion bars, ala police car. LOL
 

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Discussion Starter #5
I believe it! Sounds like a nice ride.

Do you have recommendations for the tight stall?

I also have to read up on what is needed for the swap and what needs to be replaced. Not too sure of the condition of my trans but I've replaced the filter, fluid stays red, it pulls well, shifts firm, so I want to leave it be. It leaks a bit, but really dont want to mess with what ain't really broken.
 

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I don't have a lot of experience over the years with torque converters as many of my cars were manual and/or I ran what I had if automatics - just installed shift kits/trans coolers.

The converter I went with on my brothers car, and which I will use when ready, came from Edge Racing Converters. Here is what they show for the TH400: TH400 : Edge Racing Converters, More Horsepower with More Torque Guaranteed!

Went with the "Mild Street" on my brother's car. When you click on it, it has a form you will fill out that helps them to set-up the converter for your needs.

You can check around for others, but I think the price is good as well. (y)
 

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Coan racing is another torque converter source in Kokomo Indiana, been to their plant they build the converters, Coan invented the trans brake. They have a Pontiac street torque converter 2400 stall, real good.

Also Performance Torque Converters (PTC) in Muscles Shoals Alabama builds converters, give them a call, they will build a first rate one as well and great prices too.

so PJ gave you one and here’s two more , good luck!
 

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Discussion Starter #8
Thank you both for the suggestions! Much appreciated!

I had another thought. Do you think I should start with modifying the governor or does it not have an affect on shift points other than WOT? I have the classic stock BOP Th400 shifting through gears super quick with a WOT limit of 4200rpm. Also not sure if I would need to that recalibrate after a torque converter swap.
 

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Not a trans guy, but the governor does come into play under aggressive throttle not just WOT,...very light throttle uses the vacumn modulator....as for the TC question talk to someone Like Kenny at PCT, they are super helpful and will not take advantage of you.

they build converters for the racers and will know the answers...
 

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Also those governors are easy to change the weights, lots of kits out there, you can swap the weights and try it out....not hard just have to get underneath...
 

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Discussion Starter #11
Sounds good Lemans guy. I have the kit from TCI. I've just been lining out the timing and carb so I haven't got around to it yet. 90% there now if I can get rid of the nozzle drip when super heat soaked (likely need new pump).

I'll mess with the governor and see of it helps change shift points where it wont be lugging around anyways.
 

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Discussion Starter #13
Timing should be good. New DUI distributor 15deg initial with 20 mechanical for a total of 35deg. 13 vacuum advance hooked to manifold vacuum.
 

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Discussion Starter #15
I haven't fired on this yet. I'm still debating gear swap or torque converter. I feel like the torque converter is likely the easiest/economical option as I just need to get revs past 1800-2000rpm to get going good.

If I change the torque converter is there concern with cruise below stall speed, or is that a non issue with a good cooler?
 

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Non-issue if you get a "tight" stall converter versus a "loose" stall converter. A trans cooler is always a good idea, but a "tight" stall does not generate the heat that a loose converter does.. My '73 Fury has a factory 2,500 stall converter as that is how they offered the car with the 360CI and 727 torqueflite option, but it is a "loose" stall, so it just take a little gas to get RPM's slightly up and get the car rolling. Not the best for gas mileage. It does not have a trans cooler and works fine.
 

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I haven't fired on this yet. I'm still debating gear swap or torque converter. I feel like the torque converter is likely the easiest/economical option as I just need to get revs past 1800-2000rpm to get going good.

If I change the torque converter is there concern with cruise below stall speed, or is that a non issue with a good cooler?
Just read through the whole thread. I would change the gears. That is going to do for you what you are wanting done.
Putting that higher stall convertor doesn't come without disadvantages. "Cruising" driveability can suffer. Particularly when you say 'lugging up hills". You'll probably not care for how a high stall converter will help that, but you'll love how it feels if you stiffen up the ratio. Off the line, sure, you can overcome tall gears with a converter. Is that what you mostly do with the car?
As far as money goes, what's the rear now? Stock? 12-bolt? Something else?
Buying a quality converter or new gears and paying to have them put in isn't going to be dramatically different pricewise. If the rear isn't worth/can't handle just a gear swap then yeah, it gets a little pricey. But, that's what you really need.
 

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Discussion Starter #18
I currently have the stock 8.2 rear with 2.78 gears. If I change gears I think I'm going for 3.42s or 3.55s. That would require a carrier, gears, rebuild kit, fluid, etc. Costs looking like 850+ for decent parts alone. Also looking to do it myself to save some cash.

The converters looking like it would be half that cost right now..
 

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I currently have the stock 8.2 rear with 2.78 gears. If I change gears I think I'm going for 3.42s or 3.55s. That would require a carrier, gears, rebuild kit, fluid, etc. Costs looking like 850+ for decent parts alone. Also looking to do it myself to save some cash.

The converters looking like it would be half that cost right now..
I\m assuming it's a posi, yes? If so that math is pretty good. 3.42-3.55 is going to have things wound up pretty tightly in an automatic. I hear you on the price, but I'd think of it this way. If you do the converter, it'sd not really going to be what you want. Then you'll do the gears and you'll have spent both monies. It will be great, but spendy. Do the gears first and I'll wager you'll forget about the converter for a while. Now you have some agonizing to do. What gear ratio? You can pick anything :) I just went through it. Had a 12 bolt built for my '66 GTO with the same TH400. I went with 3.31s. Plenty of gear. Really think through where/when you drive. Punch your data into one of the online RPM calculators and see what you'll be spinning at speed.
 

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Do the converter first. My '73 Fury 4,000 pound plus boat has 2.71 gears. The higher stall converter does not hurt driveability. The higher stall makes it much more fun to drive as it pulls off fast at any red light or stop. I can cruise at 80 MPH all day long keeping up with local traffic and the engine is not even breathing hard. The 3.42 or 3.55's will hurt driveability because you will be revving the engine higher ALL the time throughout the entire RPM range. You may want to use one of the tire/gear ratio,RPM/MPH calculators just to see what you speed-to-RPM's will be. If all you do is local driving, then step up to 3.55's. If you do any highway driving, keep what you have and go with the converter first. If by chance you think you want more gear, then add that later. The more inexpensive route, and easiest, will be the converter.

I gave you all the info needed, so I will not repeat it. It ultimately is your call and your money/time. (y)
 
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