How do I pick a TC??

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Revoke36

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I have no idea of my cam specs. And neither does the guy that put it together! He just knows it’s a comp cam, bored .30 over, x heads (will be upgrading to aluminum) RPM performer intake, 750 dp, 340 small block. 4.10 gears, 8 3/4 rear, sure grip, 727.

but how can I pick out a torque converter if I don’t know the cam specs?? Someone please point me in the right direction. I like to putt around town, drop the hammer every time no one is around and run it at the strip a handful of times a year. Thanks!
 
I have no idea of my cam specs. And neither does the guy that put it together! He just knows it’s a comp cam, bored .30 over, x heads (will be upgrading to aluminum) RPM performer intake, 750 dp, 340 small block. 4.10 gears, 8 3/4 rear, sure grip, 727.

but how can I pick out a torque converter if I don’t know the cam specs?? Someone please point me in the right direction. I like to putt around town, drop the hammer every time no one is around and run it at the strip a handful of times a year. Thanks!
Do you know what the cam sounds like? Can you post a video?
 
Do you know what the cam sounds like? Can you post a video?
It’s got a good chop. Mechanic recently called it a “big cam”. Guy that built it claims 400hp and high 12s in 1/4. But I couldn’t get any faster than mid 14s. Swapped out the 3.23 with 4.10 and added headers. Also upgraded to the 750 dp since then. I’ll work on a video
 
It’s got a good chop. Mechanic recently called it a “big cam”. Guy that built it claims 400hp and high 12s in 1/4. But I couldn’t get any faster than mid 14s. Swapped out the 3.23 with 4.10 and added headers. Also upgraded to the 750 dp since then. I’ll work on a video
Then I would go with something like a 3500-4200 and probably lean towards the 4200. You need to CALL a good converter company, Frank Lupo, Precision of New Hampton, PTC, whomever and tell them that's what you want but you want it tight because it's a street car. That way you can cruise around without converter slippage of the 1970s and still flash high when you do a launch against the converter. A good converter won't be 250 bucks, either. If you don't get into the 400-600 range, you're likely not getting a good one.
 
Do you know what the cam sounds like? Can you post a video?

It’s got a good chop. Mechanic recently called it a “big cam”. Guy that built it claims 400hp and high 12s in 1/4. But I couldn’t get any faster than mid 14s. Swapped out the 3.23 with 4.10 and added headers. Also upgraded to the 750 dp since then. I’ll work on a video


 
Then I would go with something like a 3500-4200 and probably lean towards the 4200. You need to CALL a good converter company, Frank Lupo, Precision of New Hampton, PTC, whomever and tell them that's what you want but you want it tight because it's a street car. That way you can cruise around without converter slippage of the 1970s and still flash high when you do a launch against the converter. A good converter won't be 250 bucks, either. If you don't get into the 400-600 range, you're likely not getting a good one.
Right on! I was hoping to go this route but wasn’t sure they would have to know cam specs?
 
Right on! I was hoping to go this route but wasn’t sure they would have to know cam specs?
I would tell them it's at LEAST a Comp 268H and it might be a little bigger.
 
If this is to be street driven, I lean toward an improvement over stock, like 2800-3000 stall.
 
If this is to be street driven, I lean toward an improvement over stock, like 2800-3000 stall.
That's barely more than a stock 340 converter. His cam is a lot bigger than a 340 cam. He needs more converter. He'll be stuck in the 70s with your suggestion.
 
He does not need an 8", 5000 rpm stall like mine (ATI Treemaster) but I again suggest not to be afraid of a higher stall on the street. The highest trans temps I see are sometimes 190 - and that's at the end of a 1/4 mile run at the track. It's back to 160 by t he time I reach the pits. On the street, typically runs in the 175-180 range if that. Driving it, you don't know you have a high stall TC unless you hammer it and then it just puts a smile on your face.

From the sound of the cam, and since you have a 4.10 gear, I like the suggestions above for something in the 3500-4000 range. It will really wake the car up. With what you've added, that should be a no-brainer of a 12 sec car.

BTW....NICE-looking car!!
 
He does not need an 8", 5000 rpm stall like mine (ATI Treemaster) but I again suggest not to be afraid of a higher stall on the street. The highest trans temps I see are sometimes 190 - and that's at the end of a 1/4 mile run at the track. It's back to 160 by t he time I reach the pits. On the street, typically runs in the 175-180 range if that. Driving it, you don't know you have a high stall TC unless you hammer it and then it just puts a smile on your face.

From the sound of the cam, and since you have a 4.10 gear, I like the suggestions above for something in the 3500-4000 range. It will really wake the car up. With what you've added, that should be a no-brainer of a 12 sec car.

BTW....NICE-looking car!!
Thanks!! You got me excited now! My car def needs a wake up slap!!
 
Got a tach? At what rpm’s does the car seem to really come alive through the gears?
 
Agree with other respondants. Make a few phone calls to builders and explain your engine and transmissions configuration and what performance you would like to achieve.

I went with BILTRON Automotive. Had a very good conversation and proposal on the build before deciding.

Precision of New Hampton also has a very good reputation


Best of luck
 
It's slow all right but I think NOT as low as 600 ,lol.
It's lumpier that my 230cam, that's for sure, I'll guess one or maybe two sizes bigger, so 237 to 244@.050, but a slow idle always makes a cam sound bigger that it really is.
BTW; Good job getting the idle into the basement! like that.

I think CCP (cranking cylinder pressure) is a bigger indicator to selecting a stall.
If yur running 190 psi, with those 4.10s, she won't need much of a stall at all.but
If yur running 145psi, with 3.23s; oh lordy .

Plus since the beast is already on the road, I think @12many said it best.

I couldn’t get any faster than mid 14s.
What was the mph, car weight, and elevation of the track? These numbers can be translated into horsepower. From the power numbers and weight, an approximate fastest ET can be generated. Then you just have to spend,spend,spend, to get close to it.
I like to putt around town, drop the hammer every time no one is around and run it at the strip a handful of times a year.
This is an exercise;
In First gear, with 4.10s, and 27s, 30mph is already 3750@zeroslip, say 4150@WOT . A stall of 4200, from this point on, is not gonna make a difference, especially if it spins.
In First gear..... 20mph is 2500@zero-slip, say 2800 @WOT. I'd be surprised if the tires didn't spin, the CCP would have to be pretty low. So again, a stall would Not help much if at all.. But if the tires don't spin well then , a higher stall might help. The thing is that in less than a second, your rpm will be thru the roof as the car finally does break traction.
Now, the 727 has a very wide 1-2 split of .59. Lets say you have a power peak of 5400 and are shifting the 1-2 at 6000. At the shift, your rpm would drop to 3540. So a stall of Less than that will help you nothing, on the shift.
That cam will have a powerband of about say 4200 to 5700=1500rpm.
Whereas the the rpm drop from First to Second is 6000 less 3540=2460. So on the shift into Second, the transmission drags your rpm way way down into the basement, and "off the pipe/cam". In this case you might consider a TC stall of closer to 5400 less 1500=3900, but up to 6000less 1500=4500
But I can almost guarantee you that with the 4500, she is gonna bust the tires loose, after hitting 6000 in first gear, which with 4.10s is only like 40/44 mph.
Now, the 2-3 split is only .69, so your shift rpm can be say 5800 on a 5400 power peak. Therefor, on the shift at 5800, the Rs will drop to 4000, so a 4000 stall will be about right. And she ain't likely gonna break traction at 70mph (5800 in Second).
Conclusion; the 4000 is about right for the track ....... for "the handful of times a year", that you might go.
But on the street, WOT with a 4000TC, will result in nothing but tirespin in two gears, so "dropping the hammer" is sortof a thing of the past..... unless you swap out that 750DP...... lol. Ima thinking 500AVS or a small TQ; these are adjustable Air-Valve Secondary carbs, with which you can soften the hit, and slow things down, for less tirespin.
I mean that car sounds like it could do Zero to 60 in about 5.2 seconds. What's the difference if it goes 5.2 spinning and sideways, or 5.4 straight as an arrow.

Caution, all the above numbers are fictitious and bear no resemblance to anything in reality ...other than the 727 ratios which are 2.45-1.45-1.00.. This is just an exercise.
 
If this is a street driven car 3,000-3200, anything over 3,500 on a street car is a no go for me. I have driven very high stall converters on the street, and the engine is just slipping on the converter all the time, it really makes it no fun to drive. A 4,000+ stall converter on the street is a nightmare, its like you have a manual transmission car where the clutch is just slipping all day long, and it does not start to really grab till you hit 3,000 rpm +, I really hate it. You are at a light you start accelerating the car and the RPM's jump up to 1500 before the car starts moving, and then it just slips all the time at part to medium throttle, really, really annoying. Great if you want to just do a smokey burnout on the street out of a stop light, you hit the accelerator and the converter flashes to 4,000 rpm's and the car just melts the tires, or if you are at a dragstrip with sticky tires.
 
If this is a street driven car 3,000-3200, anything over 3,500 on a street car is a no go for me. I have driven very high stall converters on the street, and the engine is just slipping on the converter all the time,

yea if you are running a 1970 technology convertor.
 
If this is a street driven car 3,000-3200, anything over 3,500 on a street car is a no go for me. I have driven very high stall converters on the street, and the engine is just slipping on the converter all the time, it really makes it no fun to drive. A 4,000+ stall converter on the street is a nightmare, its like you have a manual transmission car where the clutch is just slipping all day long, and it does not start to really grab till you hit 3,000 rpm +, I really hate it. You are at a light you start accelerating the car and the RPM's jump up to 1500 before the car starts moving, and then it just slips all the time at part to medium throttle, really, really annoying. Great if you want to just do a smokey burnout on the street out of a stop light, you hit the accelerator and the converter flashes to 4,000 rpm's and the car just melts the tires, or if you are at a dragstrip with sticky tires.
That sounds like old technology. I ordered a converter from Lenny at Ultimate Converter Concepts and he asked about my current torque converter which was a 3500 stall. I told him the RPM raises before the car moves and it feels like a manual transmission. His response, that's old technology. With my specs given he recommended a 9 1/2 inch 5200 stall and told me I will never even notice it has a big stall when driving around town. He also told me when I put it in gear at idle the car will move. He was absolutely correct. The new technology in torque converters is night and day with the old. I would call Lenny and give as much info as you can. I wouldn't be surprised if you end up with a 4000+ stall. Good luck!
 
I'm sure a convertor company could help ya if you atleast know the cyl pressures.
Exactly. It may have already been said before, but a compression test is in order. Report back with your cranking pressures.
 
If this is a street driven car 3,000-3200, anything over 3,500 on a street car is a no go for me. I have driven very high stall converters on the street, and the engine is just slipping on the converter all the time, it really makes it no fun to drive. A 4,000+ stall converter on the street is a nightmare, its like you have a manual transmission car where the clutch is just slipping all day long, and it does not start to really grab till you hit 3,000 rpm +, I really hate it. You are at a light you start accelerating the car and the RPM's jump up to 1500 before the car starts moving, and then it just slips all the time at part to medium throttle, really, really annoying. Great if you want to just do a smokey burnout on the street out of a stop light, you hit the accelerator and the converter flashes to 4,000 rpm's and the car just melts the tires, or if you are at a dragstrip with sticky tires.
Then you've not driven a modern converter. You can get a modern converter that will flash to 5000 RPM and drive around town locked up at around 1500 so you can lope around town to get groceries and ice cream. Take it to the strip, stall it up at the light and launch at 5000 RPM. Converter technology is in a completely different place than you describe now.
 
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