The Dodge Challenger Message Board

Me again, I'm looking to order a new B&M flexplate for the 340 but then I need to know if the engine is balanced internally or externally, how can I check that? It's a '73 block with a forged crank, forged pistons and steel (stock) damper; simply said, it's a '73 340 with '70/'71 internal parts. Hope anybody can help me out cause in the catalogs I see flexplates for internally AND externally balanced 340's.

Check out the balancer on the front of the crank. It will have a slight weight offset cast into it if the crank is externally balanced. The original convertor would have a weight welded onto it too.

I know where the balancer is located, you should know that Dave... Just kidding Dave, I know enough. It's internally balanced, I remember it hasn't any weights on the convertor at the moment. Thx Dave!

BTW, what convertor do you run?

TCI Streetfighter 10 inch. Because the price is right!

Ohh, maybe a stupid question but ehh... does a 340 has the 6 or 8-bolt crank? Need to know to order the flexplate. Or could the 340 has both of them; hope not! thx

As far as I know (and off the top of my head)only the Hemi came with a 8 hole crank from the factory. Don't trust the TCI tech people to give you advice. I like the price of their parts but their advice stinks. They can't even read their own web page....Says Dave two converters later.

I think you will have six holes and the only thing you need worry about is do you need a balance weight on it.

My current convertor has no balance weights welded on, and there's nothing on the balancer too so the engine is internal balanced. So that won't give me troubles.

For the convertor I wasn't looking for the TCI, I was thinking about the B&M Holeshot 2400 (2400stall with 230ft/lbs@2500rpm engine, mine produces +/- 310@2500), the Mopar Performance convertor 175K (they say 2500stall) or the one Mancini sells (2500-3000stall). I heard positive comments about the B&M, but does anybody know the ones Mancini sells?

The B&M unit is a good one. I don't know what Mancini is selling. Don't forget with your engine producing more torque it will stall higher. Maybe 2800?

Yeah I know Dave, that's why it's a good one for my engine, the B&M convertor. It has good stall speed. You know my cam will work from 2800-6900, so for max. performance I would need a higher stall; around 3000 I guess. But I don't want the stall to be to high cause the car will see more streets then strips. And on a street car you don't want too much stall in my opinion.

I wouldn't know how much the stall increas compared to the torque increase. Maybe I need to contact B&M, they will know how much the stall will be with my torque. And another plus is that B&M has also good prices; 280$ for the TorqueFlite 727, 10" bolt pattern. It's a 11" convertor.

I think the TCI 11 inch is about $250 now so that is quite good.

The main thing about having the right stall speed is how it drives on the street.

When I was using an 11 inch with not enough stall for my cam it was trying to drive away all the time. I had to stand on the brake hard to keep it moving off. Sometimes the engine stalled when braking hard to a stop. It would not idle above 600rpm in gear which is a bit low for a cam like mine!

With the 10 inch I have now it idles higher (I have settled for a 900rpm idle speed) and it still only just starts to creep forward slightly if you don't have the brake on. To pull away from a junction or something now you have to increase the rpms to about 1500-2000 and it drives off. Once it is moving the idle speed will keep it rolling along in traffic.
Just right really.

However. On the drag strip with the slicks on it is still slow in picking up the rpms away from the line. I am going to fit an exhaust balance pipe this winter. This will make the exhaust more quite (shame!) but might also just give me a little extra torque to pull away with. This should raise the stall speed a bit more. Fine for the strip but will it be ok on the street?

I will let you know when I do it.

Know what you mean Dave, it's hard to make a extreme car good at the street AND the strip with the same setup! I think I will go for the B&M.

I think it will give a stall speed somewhere near 2600-2700 which will be good for the street use. And it will see more street then strip (4x a year) so that's more important at the moment. And with a 2700 stall it won't take long to go in the cam range with 3.91's in the rear. (The car's not so heavy as yours 340/440, maybe that also makes a difference) So on the strip it will also do it's work!

The class I'm gonna drive (streetmachine) has a min. ET of 13.500 which I should be able to set now already. So when racing I need to make one good ET near the 13.5 to qualify and after that pedal to the metal and see what it can run!

But I won't install a balance pipe, I want the real sound. BTW, anybody know if there's a big difference between the old flowmaster 40 series and the delta flow series? I heard they don't make the old ones anymore.

I work for a converter remanufacturer / transmission parts supplier. All Chrysler engines with a cast iron crank require a converter with weights on it, unless you've had the engine balanced. If your engine has a steel crank, non weighted converters are the correct way to go.
Flex plates for all Chrysler engines fall only into two types, of which there are two different models.
1st. For 12" Inch convertors, with even or uneven crank bolt patterns.
2nd. For 11" Inch convertors, with even or uneven crank bolt patterns.

The HEMI of course had its own.

On the high stall convertors we make, the convertor bolt pattern/mounting pads are made for the 11" diameter flex plate.

Nothing complicated about either item.

On high stalls, your convertor should stall approximately 500RPM over where the cam starts to make power. Therefore, if the cam starts to make power at 2600 RPM, the convertor should have a stall speed of around 3000 RPM.

We do not recommend a converter to have a stall speed higher than 2700 RPM, if the car is going to see a lot of street use. In my 71 340 Duster I used to own, with the 3.55 rear end, a 10" (3500 stall) converter was usless driving the car back and forth to work. Engine had to buzz past 3500 RPM to get past the stall speed, which meant that I drove back and forth to work in 2nd gear, and even back then with gas at only $.50 a gallon, it took a big dent out of the wallet

That is because your engine had a broader power band than the convertor was calling for. My 10 inch "3500 stall" convertor drives like a normal car. I only need to increase the rpm of the engine a fraction to drive away with my 440. With a lower stall 11 inch I was having to stand hard on the brake to stop it pulling away.

Dave. The reason you had to stand on the brakes hard was the engine is producing more power than the brakes can handle. Typically, if you put a transbrake in a transmission, you will instantly gain 500-800 RPM more than foot braking a car.
At the drag strip with my Duster, with either the 10" 3500 stall or the 11" 26/2700 stall convertor, the car would start to push itself through the lights at 2-2100 RPM no matter how hard you stood on the brakes. To take advantage of the converter, I would bring the engine RPM up just under where the car would move forward, and on the last light, nail the throttle. On either conveter, it would then flash to the manufacturers stall speed.
Different strokes for different folks, but most high stall manufacturers advise that stalls in excess of 25/2700 are not for daily driving. This is true, be the engine a big block or a small block, running what I'd call street gears.

But a trans brake would be no use driving in traffic would it? Not only was I having to stand on the brake but the idle rpm in gear was pulling down to 600rpm. Much lower than the cam would like the engine to idle at. With the 10" convertor it now idles at 900rpm and drives normally. My engine has little torque at idle and low rpm. My understanding is that this is why the stall speed seems so low. More torque at low rpm would make the converter stall higher. Or have I got that wrong?

Remember, Chrysler supplied both 11" and 12" converters for the 440 engine.
If you had a stock 11" Chrysler converter and put a lumpy cam in it, the stock converter could and would give you a problem with stalling, etc., at low RPM.
Typically a stock converter will stall somewhere between 1400-1600 rpm.
There is probably one of the best articles I've ever read on high stall converters and what you should be looking for in the August 2002 issue of Car Craft magazine.
You can run a trans-brake on the street if you so desire. Until you apply the solenoid to activate the trans brake, the valve body will operate just like a manual valve body, ie you have to manually shift from 1st to 2nd, 2nd to 3rd. Trans-brakes are not cheap and are not normally found on a street driven vehicle. That said, I have an aquaitance that runs a GM Nova with a 5500 rpm high stall in it, along with a full race Powerglide transmission. The car of course only sees street use on nice Friday or Saturday nights, and of course the drag strip.

My 11 inch was a TCI 2800rpm stall item. Not a stock 11 inch.

My understanding is that the stall speed of a convertor depends on the amount of torque. Long duration cams move torque higher up the rpm range and so you have less torque (and higher stall speed) at low rpm. That is why you need a high stall converter on an engine like mine. If you use a high stall converter on a stock or near stock engine then yes indeed the stall speed is too high for normal street driving. But the more radical the engine the lower it will stall with any converter. Unless you increase capacity or use forced induction of course.

Dave. Drop me an email at home.
If you can, give me the engine size, hp and torque if know, cam specs, axle ratio,& ire size.
Email at home is
VE7ABC@RAC.CA
THANKS...GRAHAM.