Help from gear heads please...

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bighammer

bighammer

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Today I called Hughes Performance to get a quote on a Torque converter. I went away feeling pretty stupid. Granted I know little about TC's and not much about engine building either. But what the tech told me was more than a little surprising to me.

My car (1970 Dart) is getting an engine swap. I'm taking out the worn out 318 and putting in a remanufactured 360 (1990 roller cam) I have removed the TBI and have a Weiand Action Plus intake with a Demon carb. Factory HP manifolds w/ 2 1/2" dual exhaust. So other than the intake and exhaust, she's totally stock.

The guy from Hughes suggested a "Pro Street" converter, part number 90P ($445) he says it will stall at 2200. I thought that was a wee bit low, I wanted 2500 to 2800. He said that combo would not work well with my car. I told him I was thinking about a different cam. Just a mild cam, something like what Mopar put in their factory high performance 340 cars in '68 and '69. Then he said that would cause even more problems for me cuz those 340 cars were high compression around 10 to 1, my engine probably has only 8.

Now I don't know what to do! I'm only planning on driving the car on the street, but it like performance modifications to make it a little more fun to drive. Shall I stick with a factory high stall ( they are on eBay for a couple hundred) or go with the Hughes "Pro Street" ($445)

If I was to contact a custom converter builder with my specs above, what do you think they would recommend, and who would you suggest I contact, and how much does a custom converter cost anyway?

Sorry for so many questions at once, but you guys have always been awesome at providing answers and suggestions. I'm not a mechanic. Lol, But I do know a guy who's brother in law has a friend that knows one.
 
The factory 340 cams aren't that "big" really.
You can go up to the likes of a Comp XE262 without the need for a high stall.
Running too high a stall will make your car thirstier is what I was told by a shop once.
 
Maybe he was just trying to unload some shelf units that have been gathering dust, a good convertor builder is gonna ask two or three days worth of questions about the car and everything within 20 feet of it.
 
call a few diff ones and compare, ask lots of questions, at least $500 dollars worth of questions which is a fair sized chunk of money to invest.
 
Actually he was about right for a stock or above stock cam. Even a 262 xe has a powerband range I believe starting around 1700 rpm. You want the converter to come in above the powerband of the cam. That way it allows the motor to spin up faster to the powerband.
 
The factory high stall was around 2500-2800. Call PTC.
 
Judging by what you do with the car - I think you should be lower than his recommended stall, not higher. You are not racing the car - you're cruising and driving the car. You don't mention gearing, but I'm guessing it's numerically lower rather than higher, and your cruise rpm is lower. Even the small cams in 360s start right off idle. IMO - stick with a stock convertor, and if you want a little more punch - change the rear axle ratio slightly. Then take a look at the convertor. Otherwise you'll just make a lot of noise, generate some heat, use a lot of fuel, and the car will feel slower under part or cruise throttle situations. Lower/tighter is better with a mild engine, and you have a mild engine. If you cruise in it, keep the brake stall lower than your cruise rpm at 50mph in high gear. Chances are that's lower than 2200.
 
In a deal like yours I've found the factory "cop car" type converter to work quite well. It's the 11". Get one from a good rebuilder and it will work well and won't cost too much. After it's been rebuilt they gain a little more stall. Summit or Jegs sells one that's about the same also.
Neal.
 
bighammer said:
Today I called Hughes Performance to get a quote on a Torque converter.
Click to expand...

That was your first mistake.

Get a good converter, it's shouted from the roof tops daily. I have a PTC unit it's the shizz. Never again off the shelf to me. They ain't even that expensive, $515 shipped for a 9.5" unit, drives like OEM till you mash it. No brainer.
 
So what's the deal with the different diameters of converters? From what I've gathered, factory stock is 11" but I've heard of sizes from 8, 9, up to 11". Does the smaller size give an advantage, similar to a lightened flywheel?
 
I think your mild motor doesn't need this much over-thinking.

Im not knocking your build, good for you for getting something going. But I doubt if you put a $300 hughes 2500 in (yea that's how much they are from summit, and hughes are tight anyway so it'll likely be right around 2000) or paid $800 for a custom built converter you wouldn't even notice the difference.
 
i'd get a 2500 from dynamic or ptc
i'd get a slightly larger cam than stock

also if that's a cast crank (externally balanced) remember your converter OR your flex plate (1 or the other not both) needs the balance offset. most get the neutrally balanced torque converter and then get a b&m flexplate or whatever
 
bighammer said:
So what's the deal with the different diameters of converters? From what I've gathered, factory stock is 11" but I've heard of sizes from 8, 9, up to 11". Does the smaller size give an advantage, similar to a lightened flywheel?
Click to expand...

The diameter is a function of it's efficiency with a given package. An 11" is efficient with fairly low stall speeds, but would be too inefficient if they tried to modify the internals to work well at say - 3K rpm. To add fuel to the confusion fire - there are 11" (these are stock low performance factory units), 11" factory high stalls which are really 10.5" diameter, 10" aftermarkets that are actually 9.5" units that use a GM core casing, and 9.5", and 8" units. Generally the smaller the diameter, the higher the stall speed. There is a tiny bonus from smaller diameters - but it's nothing to really consider a bonus.
You can spend more to get a custom 9.5" unit from PCT, or Ultimate, or Dynamic. But in truth - I think a factory high stall unit would be fine and fit the budget. Depending on your package - ("package meaning the whole combination of engine, transmission, car, gearing, etc) I'd expect something like that to stall around 1800-1900 rpm which should be fine for the cams you mention in that longblock. It will also get decent gas mileage.
 
STEP 1 Decide what cam you want to run

STEP 2 Decide what gear you want to run

STEP 3 Have a custom converter built to match your combination

Think about unsatisfied you will be after you spent a couple of hundred on a cheap converter and all the work involved in swapping it out to find it is barely better then the stock converter. For a little more money you can get a converter that will put a smile on your face when you mat the gas and cruise like a stock converter.

On another build of mine I went from low 13s to the low 12s going from a $300 off the shelf converter to a custom converter ($525 IIRC). That combination eventually went 11.70s. I recently swapped in a stroker motor and that combo with that converter is close to dipping in the 10s. (it is probably time for a better converter)
 
call ptc they have my vote 2 I have a couple of there units they work:blob:
 
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