New torque converter?? (and cam question)

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DadGum_Teen

DadGum_Teen

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I am looking to swap the stock torque converter for a new one in my 360. It all started when a few of the flex plate legs snapped apart, so now the transmission is coming out :cheers:

Right now the camshaft is a CompCam 268H, the car weighs 3350-3400lbs, has a 3.23 gear, and I drive it almost daily. The car will be used at the strip frequently on the weekends once it gets updated.

I am highly considering getting the TCI Breakaway converter (stall speed 2200-2400) and was wondering if anyone has opinions on this. I will soon be switching camshafts so I am also planning for the future.

Right now I am looking to swap for something similar to a CompCam PP280H or XE274H. So I am hoping the Breakaway could match well. If you need any other info I'd be glad to give it.

And for the cam question... Whats the maximum lift I could run on the stock rocker arms? I am planning on switching rockers when I change the cam... But if something came up where I had an opportunity to swap the cam without money for rockers, whats the biggest I could go? I heard from someone it was in the .470 range, but I need more opinions than one.

Thanks
 
I saw this on a wall at a engine parts supplier " Us picking your camshaft for your motor is like us picking your next girlfriend" I took it that they got tired of people asking which camshaft they needed in their motors.

You need a camshaft matched up with the rest of your motor basically.... like compression. I wouldn't go any higher than 470 like you mentioned with your camshaft because of stock valve train. I don't know the rest of your motor package but going any bigger with the cam could be a mistake.

I would pick the cam first, get the motor running like a scalded cat, think about the gearing also (I like 3:55 gears or lower) then pick the converter. A good converter is just as important as the motor, rearend, and trans. Call these guys when you're ready to pick the converter.

http://dynamicconverters.com/home.htm

You'll have to tell them every little detail on your set up, intended use, etc.... for them to build you a converter to fit your car NOT A OFF THE SHELF CONVERTER!!! It will cost you a little more but it would well worth it.
 
mullinax95 said:
I saw this on a wall at a engine parts supplier " Us picking your camshaft for your motor is like us picking your next girlfriend" I took it that they got tired of people asking which camshaft they needed in their motors.

You need a camshaft matched up with the rest of your motor basically.... like compression. I wouldn't go any higher than 470 like you mentioned with your camshaft because of stock valve train. I don't know the rest of your motor package but going any bigger with the cam could be a mistake.

I would pick the cam first, get the motor running like a scalded cat, think about the gearing also (I like 3:55 gears or lower) then pick the converter. A good converter is just as important as the motor, rearend, and trans. Call these guys when you're ready to pick the converter.

http://dynamicconverters.com/home.htm

You'll have to tell them every little detail on your set up, intended use, etc.... for them to build you a converter to fit your car NOT A OFF THE SHELF CONVERTER!!! It will cost you a little more but it would well worth it.
Click to expand...

I have already picked which camshaft(s) I would like for the engine after doing a little research. I am interested if the information of cam specs, weight, etc. was enough to tell me if the torque converter I'm looking at could be suitable. And if not, I could supply the additional information.

I am just not aware of the average peak torque ranges of different cam duration grinds due to lack of experience. This is where I am seeking advice. Because I'm pretty sure I can find someone around here who has a good idea of how a camshaft grind would react, as long as it's not thrown in some bogus build combination. Which could then lead to knowing if the torque converter could be suitable :)

I'm just trying to make sure that I get a torque converter that can work well with the power range of the current or future cams.
 
You can go over .500 with stock rocker arms. You'll just need to change valve springs and have the heads worked on to cut down the guides. Use positive seals.

Which cam did you decide to use.
 
rumblefish360 said:
You can go over .500 with stock rocker arms. You'll just need to change valve springs and have the heads worked on to cut down the guides. Use positive seals.

Which cam did you decide to use.
Click to expand...

That makes me feel better. The heads have already been worked over and have new valves and springs (not sure of the rate but it's for sure heavy enough, possibly replacing though).

I am most likely going with the CompCam XE274 with 1.5 rockers
 
I wouldn't use a TCI Breakaway. Won't be much better than stock. TCI doesn't have the best reputation anyway. A ten inch from a reputable company, around 3000 to 3500 stall, would probably be well suited for a XE274. Don't underestimate your converter needs. IMO, seems like a lot of people try to run too much cam for their stall speed. If you are only wanting a converter in the 2200-2300 range, it would probably be better to stick with the 268 cam you already have.
 
If you want the "best" converter for your car give Lenny at Ultimate Converter a call he'll tell you exactely what you need and then build it for you..some of the best money spent on my car was with him..
 
So what is the rest of the combo? What's been done to the engine? What exh? Intake? Carb? Ignition? Heads? Be very specific. If you have a current engine, you have to know all about it to get the right cam, and then with the right cam, you can pick the right convertor. All the parts work together, so tell us what else you have for parts.
 
Alright, i got a couple replies here.

forphorty: (cool name)
Just curious, whats your reasons for not liking TCI? I don't know a whole lot about most companies histories. And if I were to choose a different company for an off-the-shelf converter, what should it be?
Both me and my dad trust B&M for the most part, but he had a terrible experience with warping a brand new converter back in his days (along with the momentary pause it had during a launch). So he is iffy.

stroked 340:
I wish I could order up a custom converter, but I'm just not willing to spend the extra money at the moment. If I was, I'd just have someone pick a custom cam grind for me too :)

moper:
Its a 360 with a Holley 670SA,
Performer RPM Airgap manifold (port matched),
Fully ported J heads 2.02/1.60 valves (Int./Exh. [email protected] lift is 258/183),
9.3:1 static compression
Hedman long tube headers (1 5/8" primary), 2.5" x-pipe
Planning to shift at 6k
This is the cam I was considering http://www.compcams.com/Cam_Specs/CamDetails.aspx?csid=628&sb=2
With that cam it would end up having 142psi cranking pressure.
It is kind of low, but the 268h right now would put out 147psi, and I have never noticed anything sluggish about the bottom end. And I understand that the numbers are for perfect conditions.

And I'm not for sure if the carb would be getting on the edge of being too small, but I had a 750 demon on once and it seemed overkill on the bottom end
 
How do you know it's 9.3:1? What does it have for cylinder pressure now? (measured, not calculated)
 
Another converter company to call is PTC, i've had them build me 4 in the past 5 yrs. & theres none better for the "price", thats just my opinion, take it for what its worth.
 
No need for a custom grind cam..all my cams are off the shelf,the converter is one place you DON'T want to be cheap...
 
I have no direct experience with TCI but i have a couple of friends who were not happy with their products. I've read a lot of negative things about them, and few positive. I believe that they have been getting by on name recognition. People tend to buy B&M and TCI because they have heard those brands for years and they sell them at Summit. I run a Dynamic in my car. The companies owner, Frank Lupo, is a Mopar racer. Turbo Action has a great reputation for Mopar converters. As others have already mentioned, Ultimate and PTC are also good choices.
 
Moper:
Took liquid measurements before the engine was put together, and if I remember right it was pumping out about 145psi or a little under at about 5k miles. I'm not certain of this number though, and the car isn't in the position to be cranked on

And I guess I might as well call a few of the places and get quotes on converters.
And if I did go with a higher stall converter, how bad would something like a 2800-3000 be on the street if I was recommended one? (which I kinda doubt, but for just in case purposes).
 
DadGum_Teen said:
Moper:
Took liquid measurements before the engine was put together, and if I remember right it was pumping out about 145psi or a little under at about 5k miles. I'm not certain of this number though, and the car isn't in the position to be cranked on

And I guess I might as well call a few of the places and get quotes on converters.
And if I did go with a higher stall converter, how bad would something like a 2800-3000 be on the street if I was recommended one? (which I kinda doubt, but for just in case purposes).
Click to expand...

A well built 2800 stall will act almost stock untill you romp on it, I paid 285.00 for my 11" 2800 stall from PTC, they install balloon plates in all there converters now, i don't think you'll find a custom built converter for this price with a balloon plate, in fact, i can almost garuantee it!! Or you can step up & get a tight 9.5" for 385.00 that'll flash around 28-3000, then if you ever need more converter, just send it back & for a small fee they will change the stall, you can get 44-4600 flash pretty easy from a 9.5".
 
DadGum_Teen said:
And I guess I might as well call a few of the places and get quotes on converters.
And if I did go with a higher stall converter, how bad would something like a 2800-3000 be on the street if I was recommended one? (which I kinda doubt, but for just in case purposes).
Click to expand...

Now you're getting somewhere... go where your heart tells you to go DadGum...

First of all when you call Dynamic or the other place and give them your information don't be surprised that they recommend a stall higher than what you have in mind. They might even recommend something like 3500 stall but their converters are made with street driving as well as racing in mind. Its happen more times than one that I have seen this on here where the guy is wanting a converter and they blew the guys mind. Hope you understand what I'm saying. It will be tame as you leave casually from a red light but if you nail it.... it will flash up to 3500 RPMS and it will look like you're shot out of a cannon. Of the shelf more likely will not act this way. That's why it is worth it to spend a little extra money now.
 
IMO, the 268 should have more than 145... That's why I'm doubting the ratio and what concerns me is a larger cam will feel softer as a result. So my advice would be to leave the cam in place, run something cheap like the MP/Mancini Racing units or the stock one, and find a set of gears for it.
 
9 1/2 dynamic converter = 3500 stall

A 107 center line will be better for low end torque.
 
The cam you have now is good for the gears you are running.
A good cam would have .530 lift and a tighter center line like a 108 or 107.This is because your heads flow well at .500 lift.
It's just hard to find a cam with so much lift and not loose cylinder pressure due to a very high duration.

QUESTION>>>Are you running adjustable rocker arms???
And what 268h comp cam are you running?????

When you go higher in duration you will loose cylinder pressure due to the intake valve closing later.
A tighter center line will close the intake valve sooner and let you run more duration with out loosing cylinder pressure.
In the end you have to look at when the intake valve closes and compare that to the cam you have now in the engine and what you get for cylinder pressure.
Before you go any further check your cylinder pressure on your motor when fully warmed up.

Comp cams is saying that you need an adjustable valve train to run the cam you picked out.
 
I'm a little chicken when it comes to stock mopar valvetrain. I installed a .474 lift Mopar cam and took out a .425 lift cam in a 273. The adjustable valve train had been ditched at some point. I was going down the highway and lost a cylinder.... turns out the push rod came through the stock stamped steel rockers. There was more than one on different cylinders but they didn't come through yet. I couldn't tell if I did anything wrong because it ran good, timing was correct, cam installed correctly, etc... I replaced the destroyed rockers and drove the car for awhile before I took it out for the 360. I guess I should have at least bought new stock stamped steel rockers for it but I would have never thought of doing that since they looked fine when installed.
 
I think I'm getting somewhere with the information I've seen, I'll try to do an updated pressure test, with the motor hot, and a little different cam grind. As long as the flex plate doesn't try to wobble around hitting every dang thing again, I'm sure it will be fine :)
 
moper said:
IMO, the 268 should have more than 145... That's why I'm doubting the ratio and what concerns me is a larger cam will feel softer as a result. So my advice would be to leave the cam in place, run something cheap like the MP/Mancini Racing units or the stock one, and find a set of gears for it.
Click to expand...

Here's a neat calculator I've played with before, the same team also has a number of others that can really get you distracted 8)
http://www.wallaceracing.com/dynamic-cr.php

For the harder to find input info, I'm pretty sure the stock rod length is 6.123", someone please correct me if I'm wrong. And my altitude is 700ft.
Intake valve for the 268H closes at 60degrees ABDC. It turns out to be 147psi CP with the formula. And I did a test today with the engine warm and it is verified at 144psi at 3 different cylinders (didn't do all).
 
T67POWER said:
The cam you have now is good for the gears you are running.
A good cam would have .530 lift and a tighter center line like a 108 or 107.This is because your heads flow well at .500 lift.
It's just hard to find a cam with so much lift and not loose cylinder pressure due to a very high duration.

QUESTION>>>Are you running adjustable rocker arms???
And what 268h comp cam are you running?????

When you go higher in duration you will loose cylinder pressure due to the intake valve closing later.
A tighter center line will close the intake valve sooner and let you run more duration with out loosing cylinder pressure.
In the end you have to look at when the intake valve closes and compare that to the cam you have now in the engine and what you get for cylinder pressure.
Before you go any further check your cylinder pressure on your motor when fully warmed up.

Comp cams is saying that you need an adjustable valve train to run the cam you picked out.
Click to expand...

I'm so confused :(
Because the 274 cam has an intake centerline of 106 and it sounds like your suggesting a cam with a later centerline would offer more compression.

But couldn't I just advance the XE274 cam a few degrees and have the same compression as the 268H? They both have a lobe seperation angle of 110, and intake centerline of 106. But the 274 intake valve closes 3 degrees later than the 268 because of the duration. And if I could get the same compression, (since I'm fine with what it has right now), how much would I advance it? And are the dodges set up to change degrees by 2 degree intervals, or 1 degree intervals? I cant remember.

I still don't 100% understand camshafts, but wouldn't the 274 get the same compression as the 268 if the 274 was advanced 3 degrees?

Sorry if I repeated myself a lot
 
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