904 torque converter recommendations?

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Valiant Showoff

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Alliance, Ohio
I'm in the market for a new converter for my 904 behind a 360 in my street/strip 68 Cuda. The last converter I bought was an 8" ATI back 25+ years ago and wondering who I should be calling this time around.

THANKS

Cuda-1.jpg
 
If you would like an actual detailed recommendation, perhaps you could give some detailed description of your car?
 
Depending on where you want to go with any solution, find a place that'll talk to you about the build and performance expectations you have.

PoNH
Biltron

Etc
 
68 Cuda
360 stock stroke
10.2 compression
Cam 241/247 duration at 050, .545 lift, 110 lobe separation / hydraulic
Eagle rods
Lightweight Ross pistons
LD340 intake
Holley 800 double pumper
Doug’s D-453 headers/2.5 exhaust
3.91 gears
26” tall tires
 
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Did you forget the cam-specs on purpose?

For street;
My choice would be; ~80% of the rpm of peak torque, plus or minus 200rpm, rounded to the nearest 100rpm.
This depends mostly on the gears. Towards the high side for hiway gears, the low side for performance gears.
Thus for a torque-peak at 3700rpm, I'd be looking at 2960 +/- 200, and rounded.
So then, I'd get a 3200 for 2.94s, or 2800 for 3.91s

A cam to torque-peak at 3700, takes about 232@ 050, depending on several factors such as; the heads, the cam's installed LSA, the Ignition timing, and the cylinder pressure.
232 @050; on a 110LSA/ FTH, could be ~278 advertised.

Your results may vary.
 
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a 241 cam will powerpeak around 5400, with a resulting Torque peak at around 3900, and 80% of that is 3120
Thus your selection is from 2900 to 3300
However, in your case, the cylinder pressure, at just 10.2 Scr is gonna be lower than ideal. Using the Wallace-Calculator, I put you down for 1000 ft elevation, with an Ica of 68*, with which the Wallace then predicts is 156psi and a P/V index of just 128; the weakness of which I'm guessing, is frustrating you.
So then, even tho my formula indicates 2900 to 3300, and normally with 3.91s this would want the 2900, in your case, I would go to the hi-side of the window at 3300.

IMO, tho, that cam is way bigger than it needs to be, for a streeter, and the rear gears are too small for it. So Ima guessing you are Dual-Purposing it. In which case, I would add another 100 or even 200, getting you up to 3500 stall.
--------------------------------------------------------------------------------
The trouble is;
Firstly;
that when you get tired of that gas-hog cam, and stick a 228@050 in her, the 3500 is way too big for that. The 228 will torque peak at ~3600, thus wanting a stall window of 2880 +/-200, and with 3.91s, will like a ~2700 stall.
Secondly;
the cylinder pressure will rise to ~166, and the V/P to 144. While the V/P of 144 is an excellent number; way stronger than the previous 128, (about 12.5%, about the equivalent of adding another cylinder); the 166psi is borderline too much pressure for pumpgas and open-chamber iron heads. Borderline. I'd be willing to try it with the 3.91s, and a 2800, then play with the Ica to see what I could get away with. But, the 228 cam, with say a 2800 stall, will pull 3.23s quite happily, and burn way less gas doing it, and especially so, if you can run the stall down to 2800, without detonation.

If I installed a 228* cam, I would get it on a 107 LSA, to try and keep some overlap, to keep the power over the nose as high as possible. If you pick the right cam, you could get a 4>6 degree ICA window to work with.
Lemme show you what I mean.
I'm guessing your current cam is advertised at;
284/292/110 ; in at 106, the events are
284 intake/112 comp/100 extraction/292 exhaust/68 o-lap
Next is a theoretical custom 228/236/107LSA cam
272 intake/118 comp/109 extraction/282 exhaust/61 o-lap
This is installed at 106, just 1* advanced. You could easily install this cam 3 degrees in either direction.
Lets retard it to in at 109 and see what happens. I get
272 intake/115 comp/112 extraction/282 exhaust/61 o-lap

Now let's compare yours (in black) to the one in purple;
the rpm of peak power has come down ~300rpm
The pressure has gone up to 162 psi
Extraction is up a whopping 12 degrees, and
the overlap lost was just 7*

now the interpretation;
Power is down a good 5%
Peak torque is 300 rpm lower and a good 5% greater
The increased cylinder pressure means better throttle response and quite abit more low-rpm/midrange torque.
The extra degrees of extraction are gonna really boost your hiway-fuel economy. I mean really!
The greater pressure together with the greater extraction, are gonna boost your city economy.
The extra pressure is gonna let you, if you are so inclined, run less rear gear. This will further reduce your fuel-consumption on the hiway. They say about half the percentage difference. But in your case with the smaller cam, you can expect way better numbers than that.

However;
you did state;
Street/Strip, so I know I'm preaching to the wrong guy, lol.

But I just gotta say;
I also have a 68 Barracuda with a 367@11/1, but she's a 4-speed/and with 3.55s. It has gone 93mph in the Eighth @3457 pounds @900ft elevation, with a 230/237/110 cam. That's fast enough for me.
And she idles down the hiway in overdrive at 2240 rpm, sipping fuel.
She used to be my DD, until the rust became too embarrassing.
 
Last edited:
a 241 cam will powerpeak around 5400, with a resulting Torque peak at around 3900, and 80% of that is 3120
Thus your selection is from 2900 to 3300
However, in your case, the cylinder pressure, at just 10.2 Scr is gonna be lower than ideal. Using the Wallace-Calculator, I put you down for 1000 ft elevation, with an Ica of 68*, with which the Wallace then predicts is 156psi and a P/V index of just 128; the weakness of which I'm guessing, is frustrating you.
So then, even tho my formula indicates 2900 to 3300, and normally with 3.91s this would want the 2900, in your case, I would go to the hi-side of the window at 3300.

IMO, tho, that cam is way bigger than it needs to be, for a streeter, and the rear gears are too small for it. So Ima guessing you are Dual-Purposing it. In which case, I would add another 100 or even 200, getting you up to 3500 stall.
--------------------------------------------------------------------------------
The trouble is;
Firstly;
that when you get tired of that gas-hog cam, and stick a 228@050 in her, the 3500 is way too big for that. The 228 will torque peak at ~3600, thus wanting a stall window of 2880 +/-200, and with 3.91s, will like a ~2700 stall.
Secondly;
the cylinder pressure will rise to ~166, and the V/P to 144. While the V/P of 144 is an excellent number; way stronger than the previous 128, (about 12.5%, about the equivalent of adding another cylinder); the 166psi is borderline too much pressure for pumpgas and open-chamber iron heads. Borderline. I'd be willing to try it with the 3.91s, and a 2800, then play with the Ica to see what I could get away with. But, the 228 cam, with say a 2800 stall, will pull 3.23s quite happily, and burn way less gas doing it, and especially so, if you can run the stall down to 2800, without detonation.

If I installed a 228* cam, I would get it on a 107 LSA, to try and keep some overlap, to keep the power over the nose as high as possible. If you pick the right cam, you could get a 4>6 degree ICA window to work with.
Lemme show you what I mean.
I'm guessing your current cam is advertised at;
284/292/110 ; in at 106, the events are
284 intake/112 comp/100 extraction/292 exhaust/68 o-lap
Next is a theoretical custom 228/236/107LSA cam
272 intake/118 comp/109 extraction/282 exhaust/61 o-lap
This is installed at 106, just 1* advanced. You could easily install this cam 3 degrees in either direction.
Lets retard it to in at 109 and see what happens. I get
272 intake/115 comp/112 extraction/282 exhaust/61 o-lap

Now let's compare yours (in black) to the one in purple;
the rpm of peak power has come down ~300rpm
The pressure has gone up to 162 psi
Extraction is up a whopping 12 degrees, and
the overlap lost was just 7*

now the interpretation;
Power is down a good 5%
Peak torque is 300 rpm lower and a good 5% greater
The increased cylinder pressure means better throttle response and quite abit more low-rpm/midrange torque.
The extra degrees of extraction are gonna really boost your hiway-fuel economy. I mean really!
The greater pressure together with the greater extraction, are gonna boost your city economy.
The extra pressure is gonna let you, if you are so inclined, run less rear gear. This will further reduce your fuel-consumption on the hiway. They say about half the percentage difference. But in your case with the smaller cam, you can expect way better numbers than that.

However;
you did state;
Street/Strip, so I know I'm preaching to the wrong guy, lol.

But I just gotta say;
I also have a 68 Barracuda with a 367@11/1, but she's a 4-speed/and with 3.55s. It has gone 93mph in the Eighth @3457 pounds @900ft elevation, with a 230/237/110 cam. That's fast enough for me.
And she idles down the hiway in overdrive at 2240 rpm, sipping fuel.
She used to be my DD, until the rust became too embarrassing.

Thanks for the info, but I’m specifically looking for who to get it from. Not the specs of what it should be.
 
I’m in the same boat right now, but I just want another converter to play with. I’d used Lenny Crouteau since 94 (1st Dynamic, then TCT, and Ultimate) but he’s sold the business and retired. There’s a guy out here in the west (Dice) that some guys use. Might give him a shot. Sometimes I wish I’d left well enough alone and stayed with my 727. Had two great converters for that set up. One was fast (mid 1.2 60’s), and the other was made a little softer but would print out 1.34 60 slips like everywhere. That era was the most consistent the car ever was.
 
Turbo Action would be my first call. I went with a PTC who spec'ed and built my converter. I was not happy with the way the converter was working so I sent it back and they are trying to get the converter right. In the meantime I got a loaner Turbo Action that is a basic off the shelf converter and it works fantastic. If I ever order another new converter, it will be from Turbo Action.
 
Boosted, I'm surprised you had troubles with the PTC converter. Kenny Ford and the group there are pretty sharp cookies. I know PTC recently changed hands, but I read that Kenny and about 98% of the crew are still there. I have 3 of their converters and I used them as needed with nary a problem.
 
Boosted, I'm surprised you had troubles with the PTC converter. Kenny Ford and the group there are pretty sharp cookies. I know PTC recently changed hands, but I read that Kenny and about 98% of the crew are still there. I have 3 of their converters and I used them as needed with nary a problem.
I ordered the converter last year before they sold the company. Kenny went over my specs and told me I needed a 5800 stall so that's what we went with. When I finally got the car running and to the track this year, we found out that the converter was flashing at 5000 and not 5800. That wasn't the only thing, the converter is very inefficient down low. I literally have to stand on the throttle (4000+ rpms) to get the car to move and doesn't completely engage up top (feels like a slipping clutch) and I am seeing 1200+ rpm drop on upshifts.

The loaner converter I currently have in the car is an off the shelf 5300 stall Turbo Action that flashes at 5500, is extremely efficient down low and is fully engaged up top with 600-700 rpm drop on shifts. Exactly how you would expect a quality converter to be (today's converter technology as everyone likes to call it).

I spoke to Kenny last week and he understands the issues I had with the converter and told me to send it back and he would make it right. My conversation with him didn't leave me with a warm and fuzzy feeling but I will hold off on passing judgement until I get the converter back from them and try it out.

Everyone says they absolutely love their PTC converters which is why I went with them. Also because they were the only ones that actually answered the phone when I called to order.... lol
 
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