Hey i posted one earlier about vortec heads and cam selection. I'm running 2.73 posi and want a moter that can make power in the 2500-6000 rpm range. Will a stall make up for the high gear?? any one have any exprence. I did with my 454 2.56 car but big blocks are tourque crazy and it was fun . How will i make out with a 350 with say 350ish hp and 375ft/pnds ??

its always nice to have the gears and stall convertor..........get some 3.55s and a 2600 stall and u have a chelle of a car........ lol

Make sure you take this into consideration... if your cruising freeway rpm will be lower than the stall speed, your milage will suffer, as will the life of your converter because its constantly slipping causing lots of heat.

I get the same milage now with a 3000 stall converter with 3.73 gears, than I did with 3.23 gears.

With the 3.23 my freeway was around 2600rpm, and my 3.73 freeway is 3200.

what would the off line go be like ??
i cruze 75-80mph at 2700 rpm ish

I think I have around the same power as you, and found it much more fun to have the 3.73 in the back. Posi is a must, I did get around just fine with the 3.23. I picked up 3tenths and half a mph in the quarter by switching to the 3.73.

This is just my experiance though. I can cruise on the freeway and not worry about mucho slipp from my converter now. But again, my converter was a 3000rpmer.

off the line any bog or was it all good with the high gear the cam i have now is good from 1900-5400 good off the line not super want the 2500-6000 sreem with new heads and cam plan scared of big bog what was the stall like with the 3.23's grip and rip is what would good with the 2.73's if its possible

Really didn't have much bog, especially if you tune it right. It feels funny waiting for the trans/speed to catch up with the stall when you mash it. So you get a brief engine rev, then the tires spin. With my cam there is no bog off the line, even when I mash it from the 750rpm idle.

With both sets of gears. With the 3.73 I can just roast em a little easier now. Its not like it hits 3000rpm everytime I'm driving and spins the tires, still got to give her some gas to get the tires spinnin.

Originally posted by Twilightoptics:
Make sure you take this into consideration... if your cruising freeway rpm will be lower than the stall speed, your milage will suffer, as will the life of your converter because its constantly slipping causing lots of heat.

How does a converter know what the stall speed is? If I put the same type converter behind a 540" BBC and a 153" L6 and find that the L6 stalls at 2000 rpm and the 540 will stall at 3500 rpm, which one will generate more heat at 2500 rpm in a similar weight car?

If the cam needs gears and a converter for best results, get both gears and a converter, not just one or the other or many things, including performance will suffer. Here is an example that isnt totally accurate, but you will see what I am saying I think. Assume you had a stick car. Think of bringing out the clutch as a torque converter in an auto tranny car. If you bring out the clutch at say 2500rpm(kinda sorta simulating an auto with a 2500rpm converter) in first gear, you get going pretty easily. Think of the difference if you bring out the clutch at the same rpm off the line, but in second gear, not first. Obviously you wont accelerate as well leaving in second gear as opposed to leaving in first gear, the same way that performance will suffer trying to leave agains 2.73 gears as opposed to say a 3.73 gear. See where Im going with this example? Although the converter will help, its still pushing up agains a gear ratio that wont be right for a small block that runs over the powerband you want your too. A 2500-6000rpm 350 wont do very well with a 2.73 gear reguardless of your converter. A bigger displacement engine can deal with it a little better due to the additional engine torque, but were talking about a 350 so you dont have as much of a torque advantage.

Plus, the heat issue was mentioned and thats the biggest killer of a transmission. Not only will the motor have to work harder with the numerically lower gears cause there is less torque multiplication, but engine rpm will be lower as well(probably below the stall rpm of a converter that works with the cam needed). So the converter will be put under a lot of undue stress, and in turn, it could create way more heat than it can handle and there goes your tranny. With the vortec heads, a cam of about 224-228 degrees of duration at .050 on average will be strong over a 2500-6000rpm powerband, give or take a little depending on all of the specs. A cam like that will run best with a minimum of about a 2200-2400 converter and a 3.55 gears but Id go for a 3.73 gear and a converter that actually stalls at about 2800 rpm under full throttle. It might take a converter that is rated at 3000rpm or better to achieve a true stall speed rpm of 2800, but it depends on too many things to call like engine torque, car weight, tire height, the gearing you actually use, the quality of the converter and other things too. To know for sure what you should look at, its best to gather all the info you can about your setup and then call the converter maker of your choice cause they will know what converter it will take to achieve a particualar stall rpm with your particular setup. No matter what the buildup is, the best resutls always are found when the whole engine, drivetrain and chassis combo works together. If its not all matched, you can make an otherwise very good motor combo not run as impressive as it should.

yep that what i was looking for a 350 will not do what i want in the 2500-6000 range what i got with 1900rpm to 5600rpm with the 2.73s works well enough when i go with the vortecs and ex274 i'll have to 3.73 or 4.11 od auto or 6spd much more money will be needed but is possible
thanks for the help guys

if your cruising freeway rpm will be lower than the stall speed, your milage will suffer, as will the life of your converter because its constantly slipping causing lots of heat.This is not an entirely true statement, although it has been printed time and time again in magaznes. Read what onovakind67 is saying above.

I can tell you this... my 2600 rpm stall speed 9.5" converter does not slip much when cruising at 2000 rpm (65 mph) in OD with the converter unlocked. I only see about a 150-200 rpm drop when the converter is locked.

Stall speed is a function of input torque. Technically, converters are rated in terms of "K" factor, and not stall speed. How much input torque are you putting through the converter when cruising down the highway?

At a steady cruise It probably wont slip much at all. But, in various load situations and stop and go stuff or hills or whatever, the airplane gears dont make it real easy on the converter and thats how there can be an issue of excess heat compared to using numerically higher gears. I would assume that you have a pretty efficient converter too, due to the small diameter. You would more commonly see a 2600rpm stall in an 11 inch package or so, and the results probably would not be as good as yours maybe even during just a cruise. And finally, you may still not know cause Im sure 98% of the time, you do your cruising with the converter locked up. If you cruised with it unlocked all the time, even if it is a high dollar piece, it might not last nearly as long. I agree that 200rpm isnt a whole lot of slippage(basically 1-%), but it still mkight take its toll. If we are talking about a non lockup converter for the original posters engine, Id definitely at least try to get the converter stall speed and cruise rpm pretty close.

I would assume that you have a pretty efficient converter too, due to the small diameter. You would more commonly see a 2600rpm stall in an 11 inch package or so, and the results probably would not be as good as yours maybe even during just a cruise. Having an efficient converter is important. Pump/turbine fin angle, clearances, stator, etc all play a role in determining how the converter will behave. For more info, go here:

www.converter.cc (http://www.converter.cc)

www.converter.com (http://www.converter.com)

As far as my converter being locked all the time during cruise, this is true only at highway speeds.

Greg, since you are from Pittsburgh, maybe you can relate to my daily commute that I dealt with 1.5 yrs ago (when I lived there). Rt. 19 through Wexford... 25 mi round trip per day, 35-45 mph with hills, etc. I drove this every (working) day of the year with my 2600 rpm stall spd 9.5" converter, 2.40 1st gear (non-GM trans), 3.27 rear gears. The converter spend more time unlocked than locked when there was traffic.

I had no drivibility, or durability issues. 45,000 miles later, converter and trans are working great. This was with a SMALL external cooler plumbed inline with the radiator. Converter was a Precision industries piece. smile.gif

Oh... regarding "feel" during normal driving...

In normal traffic, pulling away from a stoplight at normal speed puts the tach needle around 2000 rpm... light throttle 1-2 shift happens at 2400 rpm, and the tach only drops 200-300 rpm. Same deal for the 2-3 shift. In OD, above 35 mph the converter locks. With the converter unlocked, the slippage really is not bad at all, unless you come to a hill, or something. Then you get a bit more slippage then a stock part.

Just some info to help the original poster envision what life is like with a converter. All-in-all, I prefer the feel of my 9.5" 2600 stall speed converter to the stock part, even for just cruising around town.

Your results may vary, particularly if you choose a cheap 11" or 12" converter. I think that is where you will run into inefficiency troubles. smile.gif

Higher stall convertors do generally produce more heat, depending on how efficient they are, the extra heat can be dealt with an extra external tranny cooler.
I really like the benefit of a lockable high stall convertor that I run in my 200 4R. It flashs to 3000 rpm, then on the highway I can lock it up and watch my tranny temp. drop 15* F. due to no slippage.

One thing that hasn't been mentioned...

Mod,
You should think of the ENTIRE combo (engine, cam, stall, gear ratios, etc)...

I guess what I am saying is, WHY do you want that other cam? If you eventually plan on also changing gears, then okay. But if you are planning on keeping those gears, then choose a cam and stall speed that will work with the current combo... With the freeway gears you have less torque multiplication, and therefore you should choose a cam that will make the most low-end power (assuming you want quicker accelaration and not just top end power)...

I know, even after maybe years, I am still learning to think in terms of " complete Combos" as opposed to "individual pieces"...

I have a 10" 3000 stall behind my 454 with 3.55s in my Camaro. Cruising down the street you wouldn't really notice the difference. At a stop it still "holds the car" fine but won't stutter and stall out like a stock convertor. The only time you really feel it is backing up it seems a little looser and when you nail the gas anywhere from a dead stop to about 30 mph graemlins/thumbsup.gif It doesn't cook the tranny fluid or make things run hot and my stall is above my cruising speed. My 454 makes over 500 ftlbs from 3000 rpm on up. I had the convertor custom built but I don't know if that really makes any difference other than price :eek:

wow good info my whole thing is when i had my 454 2.56 car when the 350 was in it would rip from 2000-6000 ish . It was just getting out of the bog off the line it wasn;t much, 0-60mph was like 6secs or less just want to eliminate te bog . Some people i know with 4spd and 3.73's or 4.11's always say thats the way to go(lower gears). I've raced them and sure off the line the bog would put me behind but when she turned on they'd eat my dust. the best was a340 challenger the guy wouldn;t beleive what i had for gears and moter. I've always wanted to try a converter with the 350 get rid of the bog and look out . The high gears should be quicker they are a more efficent way of getting the power down. Imagine a 2.56 600hp car that can hook?? It blow a 4.11 car off the road. No shifting isn;t thats why draggers use the 2 speeds
i could go 80mph in 1st 120mph in 2nd its fun
3rd is like overdrive!!

I'm guessing you're racing somewhere other than a dragstrip?

It is hard to beat the well geared cars at the strip with a bonneville-geared small block street car. Sure, on the highway or a long street you can catch 'em, I'll give you that. But a quarter-mile drag is hardly enough time to make use of bonneville-gears.

once you get the power turned on the high gears are faster then low. the trick is getting the power turned on. thats the whole thought about the stall help the low end out and have the best of both worlds. Its a crazy idea it might not work but I can go from adding stall to gears to tranny eventually. I was wondering if Somebody has tried this already there is always alot of reasons not to try somthing.... my car runs low 13 high 12 in the 1/4 at 105mph fix the off line bog and i think i could do mid to low 12's. on the strip i haven;t been beat to many times vs similar weight cars stangs or camaro's thats why i think there is somthing to high gear performance

You're right about the crazy idea... I wonder why Marv Ripes didn't think of this.

i have built the idea i believe, or should i say still working on it.

about 1 1/2 years ago i wanted to build a car with highway gears ....the 2.41.... make it a posi and put a bbc 396 in the car. i bought me a 80 z28....

why ....because i wanted to do a cheap build and i was going to use what i had allready and on top of that i wanted the z28 to look factory stock with correct color codes and rims. the only thing that would not be stock would be the engine but i wanted to make it look like it was factory installed. the way it should have been built.....lol

so i put together the 2.41 posi, put in the th350 and a stock 1600 stall. since i knew what kinda weight i would be dealing since i had own several of these kinda cars i knew it was going to be around 4000 lbs.

so i knew i would have to build for torque. and i knew that would be a challenge with a 396....since i had a lot of those over the years i knew my work was cut out for me since they like to spin up to make good numbers...

the odds were stacked against me ...everywhere...

i started with a very stock looking 396.
i knew i needed the compression high for the torque so i started with 10.2 to 1 and i needed a short duration cam to work with such a low stall.

what i ended up with on my first outing was i very disapointing 15.5 sec run at 91 mph. and an engine that rattled to death from preignition. i did what i could to control this by heavly modify the timing curve and smoothing pistons and chambers and working the quench along with carb work. the 214/224 cam was to short and the car was to heavy and stall to low.

back to the drawing board i had to modify some decisions to make this work.

i had to move the power band up from idle to 5000 rpms to 1500 to 5500 rpms. but that failed as well....my preignition was greatly less but still there with a 218/228 cam 2100 stall and a torker style intake with seperator plate (trying to keep everything under the hood. (i was running a stock intake low rise).

with the second set up i only improved into breaking the 14's.

my next go around was to move the power band up to 2500 to 6500 rpms. so in went a 233/239 @ .050 cam and 2500 stall.and a change of carbs to the 750 3310-2 carb. and had to do some porting to the heads to help out the higher rpms, keeping the same intake (torker 2) this got the car farther into the 14's around the 97 mph mark 14.50's

there was no preignition now...but lacked the low end that was needed to get the car moving. and on top of that since i changed my power band the 2.41 gears was now to high....i was crossing the finish line short of 5000 rpms not allowing me the full rpm usage.

after some caculations i decided to move to 2.73 gears. i also decided to add more compression to help the low end torque. so i got the compression up to 10.5 to 1 and since i had the heads off i did more porting to the heads. i also changed to a rpm intake and modified the carb (cutting choke horn off,cleaning up the casting flash, shaving down the throttle shaft and blades,putting in a rear metering block)modifying the cold air induction to fit under the hood. recurving the dist to come in way faster,adding roller tip rockers and rhoads lifters.and i installed new high flow mufflers along with some new tail pipes.

this got me to the 13.90's at 102 mph.

now the combo felt good and was pulling well so i decided just to tune on this combo get the carb jetted correctly and vacuum secondary's to come on at the right time, and get the timing dialed in even better, and start pulling out some of the old tricks, like wrapping the fuel lines ,oil splash shield, ditching the flex fan for a stock clutch unit synthetic oils and so on.

just in fine tunning alone i have gotten the car to run 13.50's at over 107 mph. and i know there is more in the carb yet since i didnt have enough time this year to get it fully dialed in. and i know by steping up on the stall i can improve the e.t.s since this thing 60 ft's the same everytime at 2.15 seconds. with no tire spin under full throttle from a 1400 rpm stage. its crossong the finish line at 6100 rpms now. alittle short of my 6500 rpms i was shooting for but a gear swap to the next size would send me over.....so now i just have to find more power thru fine tunning to get the rpms up faster.

i dont want to go to far on the stall then there is a good chance this thing will start blowing the tires off the line. because just with a slight breakage of traction right now i can burn the tires in first and second gear and just after the shift into third it will grab.

i dont want to go to far on the stall then there is a good chance this thing will start blowing the tires off the line. because just with a slight breakage of traction right now i can burn the tires in first and second gear and just after the shift into third it will grab.

6100 rpm, 2.73 gears, 26" tires and 10% converter slip would put you at 157 mph in high gear, you must be in the lights at the top of 2nd gear.
107 mph is usually associated with a 12.50 e.t. or lower. If you used a set of sticky tires, 3.90 gears and a .7 overdrive, you could get to 6100 at the top of third, run a 12.50 or better and still have a final drive ratio equal to a 2.73.

Originally posted by onovakind67:
i dont want to go to far on the stall then there is a good chance this thing will start blowing the tires off the line. because just with a slight breakage of traction right now i can burn the tires in first and second gear and just after the shift into third it will grab.

6100 rpm, 2.73 gears, 26" tires and 10% converter slip would put you at 157 mph in high gear, you must be in the lights at the top of 2nd gear.
107 mph is usually associated with a 12.50 e.t. or lower. If you used a set of sticky tires, 3.90 gears and a .7 overdrive, you could get to 6100 at the top of third, run a 12.50 or better and still have a final drive ratio equal to a 2.73. im going thru the end of the 1/4 mile in top of second gear. my convertor has a 6.7% slippage rate not factoring in the real mph at the end of the 1/4 but just using the avg. to get your mph posted.

according my to my figures the 2004r i have now with a set of 4.10's would match my same rpm im crossing at the lights now. if the convertor i choose or end up with has about the same slippage rate as what i have now.

this is an option that im looking at for next year.

but i think im going to try and max this combo out first in its current set up and see what more i can pull out of it....i know there is a few mph to find.

the nice thing about the combo now is what it runs at the track is the same on the street. friends of mine with there 12 sec cars at the track just cant beat me on the street. when they have there street tires on they just cant pull down the same number.....where i can.....while there trying to get traction to go im gone and they cant catch up......

it just has been fun playing with want is not the norm........this tinkering has taught me alot and really has pushed my ability to find a solution to get a heavy car/no gears moving at a good pace.......

i still think this is pretty good for such a mild bbc.....nothing radical,very calm idle and good street matters..

now the 81 camaro is the moster...lol...i get ragged on for working on the 80 so much and ignoring the "race car".......but thats to easy and the 80 is the challange....lol

but your right the car would be quicker with gears and tranny swap.......

No matter how you look at it, you have to look at everything. Even though you may have a very impressive number with a 2.56 gear, a more optimum match would go faster as long as you can still plant the tires. I always use the example of an old 10 speed mountain bike to illustrate the issue. You go fastest in top gear even though you are pedaling the slowest, but when you need to start out from a dead stop(especially trying to go up a hill) putting your bike in low gear provides the best acceleration with the power of your legs, reguardless of how strong your legs are. Gears do the same thing, they multiply torque and the more torque multiplication you have, the faster you can potentiall go. Of course if you overshoot the gear choice so that you run out of engine rpm before you cross the finish line, you can hurt your results, but that wouldnt be considerend an optimum match. Even though I say your 454 does great with a 2.56, it could probably have run faster yet with a little more gear. It probably wouldnt require as much gear as some other engines with lesser torque(especially a 340 chrysler motor, those things are revvers) gears still coulda helped. Look at it this way, you say a lot of times the other cars got the jump, but then you would blow by em once you got rolling. Imagine how much harder you woulda spanked those cars if you didnt lose to them on the jump either and throughout your whole powerband you had the benefit of additional torque at the rear wheels? It woulda been pretty ugly for them. At the same time, there is a good feeling when you can say to the other guy "yeah, its only got a 2.56 gear". They probably feel the same way you would if you lost a race and said to the other guy, "whats under the hood", and the other guy says, "its got a 267".

yah greg you got a good point but with street tires and no traction bars high gears help to hook with the bog and with a th350 or th400 high geared cars are better overall performers if you look at milage, 1/4 mile , crusing, and top end. A high gear car can do it all except 1/4 mile with a low 1/4 mile gear car thats all you can do. I just want a faster 1/4 mile power and keep the rest untill I get 5-6speed manual or od auto I'll settle for what i got . Still going to try vortec heads, ex268cam, and 2500 stall for fun
and all that is cheaper than 6 spd. And if it works good if not low gear and 6spd a od it is.
I like what I got now but I'm always looking at the greener grass i guess.