Stall and Shift RPM Question.

-
swies

swies

Wish I had more time.
Joined
Apr 27, 2015
Messages
548
Reaction score
100
Location
Wa State
My 904 shifts from 1-2 at about 3000.
If I put a 3k stall converter in it, what will happen?
Would it want to shift immediately after launch?
I believe I need to raise my stall just a little bit.
Comp Cams (XE268) says this is the largest cam that can be used with factory stall.
In gear, it want's to creep pretty good.
On top of that, my 'teen doesn't start pulling hard until about 2500.
With the low factory stall (feels like about 1500-1800) I think it would do me some good to get higher stall.
What are your thoughts?
 
3000 is way too high for a mild cam. what your imposed "3000 stall" means is the converter will slip until the engine reaches 3000 RPM. then it's supposed to lock at 1:1. so the entire time you're driving at anything under 3K, you're slipping the converter. I think a nice 1900-2100 stall (on the high side) would be more suitable. The alleged "2500" powerband you're feeling will come down greatly with a little more stall. putting a 3k in it will unnecessarily heat the trans, and put you way too far toward the top of your usable RPM range to be of practical use.

you want your stall to be pretty close to the suggested beginning rpm range. whats the Pn on the cam? "xe26" is a series with about 10 different cams in it.
 
I agree with Johnnymac on that. 3000 RPM is for a HUGE cam and very high performance engine. I have pretty aggressive engine a "non mild" cam, and I have a 2500RPM stall converter in a brand new 727 I got from Summit Racing (via Performance Automatic). A 2500 RPM stall is all I need, and a 1900-2000 will work great for you. What that means is that when you are sitting with your foot on the brake in drive at a stop light, as you engage the throttle your vehicle will start to acclerate (as if you had just started to slip your clutch if it were a manual trans) as you hit 2000RPM and say about 20mph) you are now "locked up" and your shift point has nothing to do with your stall converter, your "throttle kickdown cable" on your trans has a lot to do with your shift point...if you keep your foot to the floor that tells your trans that you are not ready to shift yet eventually it will probably shift about 4500-5000RPM on it's own (even if your foot is still on the floor) depending on what shift kit is in your trans. Same principle applies if you are cruising at 55mph in 3rd gear doing 2400 rpm (you are locked up in 3rd gear). IF you smash the gas pedal, your throttle kickdown cable on your carburetor (goes from carb down to your trans) should tell your trans you want to drop into second (and at that speed it is probably about 3500-4000 RPM) It will stay in second until you either lift your foot off the pedal, or until you hit about 5000 RPM and then it will go back to 3rd.

I am NOT a trans expert. I do not rebuild them or work on them. Just going off what I know from my car (I had the 904 and now the 727). If all this stall converter stuff feels over your heard (I have my limit and when I cross it I ask for advice from a mechanic) find a guy that works on transmissions (not your average transmission shop). Also I would highly recommend you call Performance Automatic and ask to speak to one of their techs. They can help you and you can eventually buy any parts you need from either them directly or Summit Racing for a cheaper price (they sell to summit) http://www.performanceautomatic.com/

Good luck!

Good luck..

Hope that helps some..
 
Don't buy a junk cheapo converter and you can have a 3500 stall and a tight runner at part throttle.

It's not the 70-80's anymore!

Depending on what you want to do with the car, I'd have no issue with a 3500 converter in that car. I run tight 8' units on the street and they don't drive like a marshmellow.

We put a Hughes 2500 converter behind a 360 with a XE268H and I thought it was still shy of what it should have had... that's what the owners wanted. I think they were unhappy with it but it was better than the POS stock unit. The car did get 20mpg on the freeway. :)
 
crackedback said:
Don't buy a junk cheapo converter and you can have a 3500 stall and a tight runner at part throttle.

It's not the 70-80's anymore!

Depending on what you want to do with the car, I'd have no issue with a 3500 converter in that car. I run tight 8' units on the street and they don't drive like a marshmellow.

We put a Hughes 2500 converter behind a 360 with a XE268H and I thought it was still shy of what it should have had... that's what the owners wanted. I think they were unhappy with it but it was better than the POS stock unit. The car did get 20mpg on the freeway. :)
Click to expand...

It might not be the 70's anymore, and i fully agree a $200 off the shelf converter is not usually the answer, but intentionally running an 8 inch, 3500 flash converter, in a street driven 318 car with maybe 275HP and a cam that has a max RPM of 5500 RPM...and telling a novice to follow suit?...come on now.

I want to point out I'm addressing his question with general responses, because in reality there is no such thing as a "3500 converter", as there are a million parameters that will make a converter stall where it does. You can also have an 8 inch converter that only stalls to 2K. So again, we're getting into too many generalities and novice opinions here only 3 posts in.

Op, call a real converter company...and by "real" i mean not B&M. Call ATI and ask for John. You're already getting bombarded with misleading statements (probably including mine) that are just going to confuse you and get you a mismatched combination.

my opinion is only worth what you paid for it, as well as any others given. Again, i run an ATI, and they won't steer you wrong, but it also won't be $300.
 
I didn't mention ANYTHING about what size converter he should run.

More of why I don't post much here anymore.

How can anyone explain how a car with a 3K flash went to a 3800 flash and the cruise RPM at freeway speed went DOWN 300+ rpm with the higher stall converter. Can't happen according to what I just read in this thread. Plenty of people have experienced this phenomenon and the key is to call someone like Lenny at ultimate, Sean at Dynamic and any number of other quality converter companies and explain EXACTLY what you want and are looking for. That is about the only thing that I agree with in this thread from my ill founded, according to some, point of view. I do agree, there is a lot of misinformation in the thread... :violent1:

Have fun with this one. :)
 
crackedback said:
I'd have no issue with a 3500 converter in that car. I run tight 8' units on the street
Click to expand...

I must have misunderstood the words "3500" "8" inch and "That car"

my apologies.lol i just dont want the guy to go out and buy something that isn't going to work, again why he should call a converter pro and get their opinion.
 
No argument at all about a quality converter vs a cheapo. Can a higher stall converter be made to behave on the street and have less slippage at cruise? Sure....does that mean everyone with street cars should go out and run a 4000 flash converter in 8 inch trim? No.
Why flash a 250 horse engine, with a cam that only makes power to 5000, up to 3500, just to do it? Even the reference to a a 3500 flash is subjective based on cam. said converter will flash at a certain RPM based on what cam it's working with. That same converter in another setup will behave completely different.
Am i a converter builder? NO. Do i understand that the basic operating range of a cam should affect the optimal stall speed a converter should be set up for...yes. My only point is that if your engine is falling off by 5000RPM, flashing it to 3500 when peak power is probably well below that, is pretty pointless. You've got no argument from me that a quality converter can't flash high, and behave on the street, but basic RPM range is being pretty blatantly ignored with a 3000+ flash, with a powerband of 1800-5000.

Hopefully the OP see's that a call to the techline is in order. I meant no disrespect above, I just took the said numbers to be directly offered to the OP as a suggested option, and i saw that as a cause for concern.
 
1st.
Sorry for the PN on the Cam. I typed the XE268 and with the parenthesis it gave the icon. It is in fact an XE268H with the springs, rockers, and pushrods to match.

2nd.
I did not make this clear but I know now and knew then that 3000 was way to high, I used that number for illustration.

3rd.
Most important, Thanks to all for the information.
I think I need the higher stall to get the most out of my 'teen.
With that, I was concerned about the interaction between the converter with the higher stall and the A904's "Grocery Getter" low, soft shift points. With the B&M Shift Improver that is in it now, my shifts are nice and firm but under WOT, it still wants to shift out of 1st at 2800ish, just when it is starting to 'GO". I have read that the only real way to correct this is to drop the pan and either change the weights or the springs on the governor. Way above my head.

Finally, I would not go out and buy the $200 POS converter.
For some things I believe in the local Oreally's etc. for the value. But...
For other things that will require much time and energy that I do NOT want to re-do because the El-Cheapo part I bought failed, I will rely on specialist input.
With that, I am here on this forum where there is a plethora of good advice and great wisdom, (and some not) to start the needed research and learning.
Thanks to all! ').
 
I ran that cam in my 360 (and will run it in my 408 ) and I know what you mean
the converter is one way to tackle the issue
another way to tackle it would be to get some taller gears in the back


what I do when in cruising, is let the tranny shift when it wants...usually between 3 and 4 thousand RPM

when I feel the need to rev it higher I just shift it in 1st, stomp on it and when I want it to shift, ill kick it up to 2nd
and then 3rd

got to be carefull shifting on the column but its not hard to get the hang off


now, if I could give you some advice
check to make sure both your throttle cable and your kickdown linkage (or cable) are properly adjust BEFORE you start to chase something that might not be the cause of the problem
 
I have heard that. Where is the thread on adjusting the kickdown linkage on the 904?
I have been through my Factory manual and it is vague at best.
 
swies said:
My 904 shifts from 1-2 at about 3000.
If I put a 3k stall converter in it, what will happen?
Would it want to shift immediately after launch?
I believe I need to raise my stall just a little bit.
Comp Cams (XE268) says this is the largest cam that can be used with factory stall.
In gear, it want's to creep pretty good.
On top of that, my 'teen doesn't start pulling hard until about 2500.
With the low factory stall (feels like about 1500-1800) I think it would do me some good to get higher stall.
What are your thoughts?
Click to expand...

A good 3k stall will work good. I have a dynamic 9.5" that flashes at 4,400 rpm in my 400hp 360. When idling at a stop sign I can let off the brake and the car will start to creep forward and roll, give it a little gas and it shifts into 2nd at 12to 13mph and into 3rd at about 20mph just like it's made to do. The best way I can describe a good converter is if you drive it like a little old lady it will act pretty close to a stock stall the more aggressive you get with throttle Input the more it will act like a "bigger" stall . If your the type to goose it with half to 3/4 throttle blips off a stop then it will most likely flash to it's built in stall. Best to call a good company because there is a lot more than the engine in picking a converter, like car weight, gear, tire size, driving in mountainous, hilly or flat land etc....
 
My buddy runs that cam in his 318 with a stock converter Comp cams says that its the biggest cam you should run with a stock converter,not bad for a 318 but i wouldn't run it in a real motor too small..
 
Why can't we just go in somewhere and have em swap out 4-5 or so different converters and let us test drive each one?

Splain me that. :D
 
What's the tune on the engine? You say it wants to creep in gear, doesn't start pulling til 2500 rpm. There's a lot of factors we don't have info on. If the engine needs more timing advance it will effect the way the converter acts at idle along with engine response. There's a lot of other things to sort out before jumping on a major expenditure like a new converter and they only cost time. Not trying to be a butt, just don't like seeing people spend needlessly. I can't find it right now but there was a good thread about tuning and the effect on torque converter. Maybe someone recalls it and will post the link. It was very informative.
 
Thanks for the information.
Initial Timing is @ 14* btdc.
Total is @ 34*.
Edelbrock RPM A/G, Eddy 1405.
Likes to idle at 750 in Neutral (600 in gear) at temp.

and, I agree with not jumping. I do not intend to purchase this year. (maybe a winter project) but wanted to start the research and learning process now.
Currently the car has the Econo 2.45:1 gears. I have a set of 8.25 SureGrip with 3.55's but will not start the gearing project the winter.
I do not want to spend money unwisely or needlessly so I am trying to figure out the "Big Picture" before moving forward. That being said, here is my reasoning for the stall:
1. At launch, stall is 1700-1800 rpm. That is the most I can get it to rev without creeping.
2. Motor starts pulling hard at 2500-2700.
That would lead me to believe I need just a little more stall in order to get into that pulling zone, ie. the working power band.
I have not worked with a higher stall launch before, only clutch launch's so it is new to me. I figure the more research and more info the better.
Many seem to think I am heading out this weekend to buy a 5500rpm stall so I can have it 'RIGHT NOW'.
I am not that kinda guy.
As always, Thanks to all for the info.
 
Get rid of the 2.45 gear before making a converter change. If you ran the 3.55 your shift points will change. Manually shift the car at the track.

Recurve the dizzy and get as much initial in as you can to improve throttle response. I would start at 20*

Did you degree the cam when you put it in? That thing should start pulling sooner than 2500.

Eddy 600 is a cruising carb. Run a mechanical DP no bigger than 650 for the track. You need the pump shot front and back to get things moving.
 
For sure the gears will happen before the converter. No doubt there.
As for the manual shift, I have been looking for a floor shift (mine is column) to make that happen. Little easier on the floor. Just trying to find something in my budget. (It ain't much, got two boys in College)
The cam was installed by the previous owner and was degreed....he said....no docs to back that up. He had the motor built by a shop that I knew of but closed a couple of years ago the owner passed away.
The dizzy is another 'waiting on funds' item.
As the car is Street and strip, I think I will stick with the Eddy, the 1405 is the strip version vs. the 1406 and with the help of an AFR gauge, it is dialed in pretty good.
 
Dubob said:
What's the tune on the engine? You say it wants to creep in gear, doesn't start pulling til 2500 rpm. There's a lot of factors we don't have info on. If the engine needs more timing advance it will effect the way the converter acts at idle along with engine response. There's a lot of other things to sort out before jumping on a major expenditure like a new converter and they only cost time. Not trying to be a butt, just don't like seeing people spend needlessly. I can't find it right now but there was a good thread about tuning and the effect on torque converter. Maybe someone recalls it and will post the link. It was very informative.
Click to expand...

There you go. Get back to basics. 1) compression test, 2) leakdown test,

If your cylinder pressure is in the basement, You will need band-aids like gears and hi-stalls.That cam will like a cylinder pressure of 165 to 185. The higher it is, the snappier it will be off the line.
If your TC is creeping at just off idle, its either junk, or junk.
A higher stall TC will not usually make the tranny shift at a different rpm. That is controlled by the valve-body in conjunction with the governor and the throttle pressure.
It sounds like your combo is not well matched. And thats being kind.
 
I completely disagree with the thoughts that a 3000 stall converter will slip until that rpm is reached. I ran a 3k stall with my old 360 combo and under light throttle it drove nearly like a stock converter. Crackedback's statement of "this isn't the 70's anymore is dead on". Torque converter technology has come a long way from just bending the fins over. IMO a 3k stall should liven that teen up right nice and if money is spent on a good converter it'll drive excellent.

Swies, timing is one of the most important part of tuning that you can do. Your talking spending money of a converter but say "dizzy is a waiting on funds item"? Re-curving the distributor costs about $10 if you have a welder and a timing light and can make tons of improvement on how your engine runs.

Also agree that the gear swap should come before the converter
 
fishy68 said:
I completely disagree with the thoughts that a 3000 stall converter will slip until that rpm is reached. I ran a 3k stall with my old 360 combo and under light throttle it drove nearly like a stock converter. Crackedback's statement of "this isn't the 70's anymore is dead on". Torque converter technology has come a long way from just bending the fins over. IMO a 3k stall should liven that teen up right nice and if money is spent on a good converter it'll drive excellent.

Swies, timing is one of the most important part of tuning that you can do. Your talking spending money of a converter but say "dizzy is a waiting on funds item"? Re-curving the distributor costs about $10 if you have a welder and a timing light and can make tons of improvement on how your engine runs.

Also agree that the gear swap should come before the converter
Click to expand...

The converter will definitely come after the rest of the motor is up to speed.
Just dumped the cash to get the AFR gauge and the tuning kit for the Eddy so I can get it set properly.
Trying to research the dizzy and get what I can afford that will do the job for me.
Knock - off set on E-bay is $140 and I can get the skip white limiter for it.
I have asked for opinions on this on another thread and it turned into "MSD is the only way to go" and Screw that Chinosean stuff.
That didn't help me at all.
This discussion as well as gone astray.
I have stated that I am researching information so that my end goal can be achieved and people are chastising me for "buying a 5k stall' when there are so many other things that need to be done first. I know. I am trying to learn so I don't end up with a car that does not function.
My next steps are:
1: get the Eddy in tune with the kit and the AFR.
2: Get the ignition fine tuned. (Still trying to research. I can't afford an MSD setup no matter how many people tell me, "It is the only way to go" Maybe I will learn how to limit my mech advance in my current dizzy and go that way. Still won't help with getting the all in sooner.
3: Get the gears under control. I have an 8.25 Auburn style with 3.55's that came from a Dakota. 69Mope and DRDIFF have told me it should fit good. Once again, never done a MOPAR rear end so trying to get the info on that. 69MOPE :prayer: has been a great help in this area. I really appreciate it.
4: Converter. Just starting to learn and research....

It seems like many people post just to sound knowledgeable and / or important.
I started the thread with a question since I need some help.

What does telling me "It sounds like your combo is not well matched. And thats being kind." help???
How does that get me closer to then information I am looking for?

Sorry for the rant.
 
Rant part 2
While I am on it,
Went to the track last night.
'Hot August Nights' at Renegade Speedway in Yakima, WA.
Had a great time.

15.45 @ 89.4 mph
15.30 @ 90.25 mph
15.05 @ 91.01 mph

Doesn't look too bad for a '75 dart more door with 2.45:1 open gears with single wheel spin issues.
I must be getting in the right direction.
 
You will like the AFR meter, great tool to get the carb right.
If you have an old OEM electronic dizzy just weld up the slots a little to limit total mechanical advance. File the slot to dial it in. Swap out the heavy spring for a lighter one and you should be able to recurve what you have on the cheap.
Once you limit total mechanical you can bump up the initial.
 
You don't NEED an MSD distributor. MSD's are much easier to dial in.

MP style distributors, especially the older models, generally require substantial disassembly/work to alter the mechanical advance total and curve. The initial timing on your engine is likely a bit low for where it would run best. It's lots of trial and error. There are a couple of good articles floating around that address the welding, etc.

A 360 with a XE268H and similar intake will usually make power to 5400-5500 rpm. In a 318 with the same components, making power at 5700+ would not be out of the question. Your engine may start 'pulling' at 2500, but it's going to really start "getting it" after 3500 rpm which is closer to the tq peak. I'd buy a quality converter with a flash rpm that gets you closer to your tq peak numbers.

Next time you go to the track, try increasing your timing. That engine may like as much a 40 degrees total without vacuum advance. If you advance timing and the car picks up MPH, you are headed the right direction. Pull a plug and inspect it for speckling on porcelain, that's bad and signs of detonation, back off timing a little. I agree with mderoy, it could likely use more initial timing.

I have a saying, "pick your parts, pay your money"

There's plenty of information on the internet. Some good, some bad, lots that is BS. You have to sort through the garbage to get to the good stuff, which is unfortunate. Lots of ways to skin a cat in this game.
 
Thanks to both of you. That is great information.
It was interesting to me that on the launch, there was no wheel spin however, 20 feet off the launch pad when it started to pull hard, bingo, right rear spun like I was on ice.
Gears will be this weekend I think.
If they go smooth, I will pull the dizzy and start the weld, grind process.
If as you say, I want to be in the 36-40* total, what should I limit the mech adv to?
My understanding is, I want as much initial as it can stand without detonation and without hot start problems fighting the starter. When I find that, do the math.
All in (36-40) minus initial = max mechanical.
i.e. (these numbers are just so I understand the math, not actual)
38* All in
18* initial
38*-18*=20* max mechanical.
Is that correct?
 
You must log in or register to reply here.
-

Back
Top