Stall on a Stock 904 Converter?

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73Swinger18

73Swinger18

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Anyone know what the stall would be on this stock 904 converter that came with my '73 Swinger with a 318?
IMG_20161016_201138.jpg
 
A good, crisp, 318 2bbl can take some of the "high stall" converters from the factory to over 2000 (brake torque method). Others as low as 1700.
 
My 69FSM lists it as 2100 to 2320(lol);brake-stall.
This is actually pretty good for a teener.
But if you lower the Dcr of your teener by putting a big cam in it and not bumping the compression, then the stall may drop:(
If you bump the compression up a full point with the stock cam,to say 8/1Dcr,then the stall should go up.
The brake-stall changes with torque input. "Soft" engine lowers stall;"crisp" engine raises it.With factory TCs,the range is not dramatic, but as poster "willrun" says;300 is possible; perhaps even 400.
If you slap a turbo on it, I have no idea!
 
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318willrun said:
A good, crisp, 318 2bbl can take some of the "high stall" converters from the factory to over 2000 (brake torque method). Others as low as 1700.
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Thanks. I installed the Comp Cam PN 20-223-3 and it states that it works best with a 2000 stall.
 
AJ/FormS said:
My 69FSM lists it as 2100 to 2320(lol);brake-stall
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Yes, and I actually had a factory stall that was the 2320. With good biting tires, you could stand hard on the brake and about get it there.
 
73Swinger18 said:
Thanks. I installed the Comp Cam PN 20-223-3 and it states that it works best with a 2000 stall.
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Didn't look up the cam choice, but if you have taken away torque from the 318, then you won't get the 2k.
 
318willrun said:
Didn't look up the cam choice, but if you have taken away torque from the 318, then you won't get the 2k.
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The cam is 268/280 duration and .477/.480 lift. It's bored .020, new flat top pistons, stock heads with larger valves (1.88/1.60), Weiand Stealth intake, Holley 600, and long tube headers. I hope it works when it's all said and done. Half the car is still in pieces in the garage.
 
I think it will be borderline, it will run OK with a stock converter but will jump off the line wayyy harder with just a "notch" higher stall, like 2600 rpm. I had a 'mystery' TCI converter for a while behind my 10.5:1 360 with Mag heads and small Voodoo (256/262) cam that stalled around there, holy sh** it was like being shot out of a cannon compared to the stocker I put back in in an attempt to get more mileage... didn't really work so I'm gonna put the higher-stall one back in, when I find time to drop the trans lol.
 
Before you bolt that puppy together, you aughtta calculate the exact Static and Dynamic compression ratios. Nothing is worse than expecting the big cam to blast off......and then it doesn't :(
If your pistons are too far down in the hole, you may be in for disappointment

Knowing beforehand that it will blast off, is way better than hoping;waaay better.
 
AJ/FormS said:
Before you bolt that puppy together, you aughtta calculate the exact Static and Dynamic compression ratios. Nothing is worse than expecting the big cam to blast off......and then it doesn't :(
If your pistons are too far down in the hole, you may be in for disappointment

Knowing beforehand that it will blast off, is way better than hoping;waaay better.
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Too late. Slapped the two together yesterday and installed them. Took today off after screwing with the headers!
 
What kind of pistons? I'd imagine compression would be at least 9:1 unless they're stock replacements, which is around the minimum with that cam... if that's the case the combo will work, but not nearly as well as it could...
 
MOPEkidD-3 said:
What kind of pistons? I'd imagine compression would be at least 9:1 unless they're stock replacements, which is around the minimum with that cam... if that's the case the combo will work, but not nearly as well as it could...
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Sealed Power flat 3.930 cast pistons.
 
MOPEkidD-3 said:
Part number? Compression height? Distance below decks? Dome/dish volume? lol... these values are necessary to know compression. Were the heads shaved at all?
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Not sure if any of that info is here Sealed Power Cast Piston (Carton of 8). All I saw was 1.720 Compression Distance. Not sure exactly how much he took off the head. I think it was just enough to clean up the surface. I'll have to ask him tomorrow.
 
73Swinger18 said:
Not sure if any of that info is here Sealed Power Cast Piston (Carton of 8). All I saw was 1.720 Compression Distance. Not sure exactly how much he took off the head. I think it was just enough to clean up the surface. I'll have to ask him tomorrow.
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Man I hate to break it to you... those look like stock replacements. It says "8.5:1 CR" in the specs which can change with a lot of other factors but still means something, and it's not good lol. That 318 is gonna be a turd until at least 2500 RPM, what gears you got in the back?
 
73Swinger18 said:
Not sure if any of that info is here Sealed Power Cast Piston (Carton of 8). All I saw was 1.720 Compression Distance. Not sure exactly how much he took off the head. I think it was just enough to clean up the surface. I'll have to ask him tomorrow.
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Those look to be stock low compression pistons. 1.810 compression height is the common one for 318's. Odds are your pistons are about .100" low in the hole. If you are at sea level 8.5 SCR pistons with your cam choice nets you a low 7.0 to 1 DCR at sea level. This will effect how hard the car launches. A higher then stock converter around 2800rpm might be a good choice to mask the low rpm power.
 
MOPEkidD-3 said:
Man I hate to break it to you... those look like stock replacements. It says "8.5:1 CR" in the specs which can change with a lot of other factors but still means something, and it's not good lol. That 318 is gonna be a turd until at least 2500 RPM, what gears you got in the back?
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It's has an open 7.25" diff with 2.71 gears and 205/70R14 tires.
 
T-N-T said:
Those look to be stock low compression pistons. 1.810 compression height is the common one for 318's. Odds are your pistons are about .100" low in the hole. If you are at sea level 8.5 SCR pistons with your cam choice nets you a low 7.0 to 1 DCR at sea level. This will effect how hard the car launches. A higher then stock converter around 2800rpm might be a good choice to mask the low rpm power.
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Unless my math is off, that's only 0.09" shorter than the Keith Black pistons. That doesn't seem like a lot. I wonder what the stock piston compression distance was in 1973?
 
73Swinger18 said:
Haha! I'll have to see how much he took off the deck and heads tomorrow and the gasket size used to see if I made up any compression there.
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Even if you do it's still gonna be a turd until 30 MPH in 1st gear, you'd need 10:1 or more to make up for that cam on the bottom end with stock converter and gears. Quick you gotta save it while you still can! Hahaha
 
My friend runs that same cam in his 318 comp cams claims it the biggest of their cams that can be run with a stock converter..
 
Stock 904/318 combo had two converts, a low stall and a high stall. Difference between the two of them about 3-400 rpm. Low stall typically around 1600 to 1700. From the photo, the converter you're showing is NOT an original converter, but a rebuilt. The factory does not paint converters. I don't know what it's like down South, but when I worked in the industry, two Mopar converters that were always CORE IN FIRST, HEMI'S AND 340'S.
Contact a builder of high stalls, give them all the information on your engine build and what you've put into it, rear axle ratio, tire size and what you will be mainly using your car for. This is the only way you'll get the converter that is best for your needs. Check with a number of these companies not just one to get their recommendations.

Remember, Summit, Jegs, etc. do not build converters. They buy them from a wide variety of converter builders, and at times they buy based on price. I'm not knocking these companies, but they may lack the knowledge to get you the converter for your application
At all costs, avoid used converters, as you never know of what they look like internally without cutting them open.
 
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