[74GP455]

Hi all, looking for some help/advise. Will give my details quick:
1974 GP, 4350 lbs with me in it.
Complete engine rebuild approx 3 years ago, runs strong:
455, .30 over, 1974 4X heads from a 400 (98cc) no port work, intake 2.11, exhaust 1.66.
Edelbrock performer, Holley 750 vac secondaries.
Crower 60919 cam, rhoads lifters, Harland sharp 1.5 roller rockers.
Ram air 2 1/2 manifold, 2 1/2 exhaust with X pipe.
TH400, hurts hot shift 2 kit, trans cooler.
3.42 posi, 275/60/15 Nitto drag radials (28 in tall)
Currently: Neal chance 11 in converter 2000-2800stall (from the 90s, I put it in there cause I had it on hand with intent to swap out at some point)

No dyno numbers to show you all, but I think I’m making 375-400 hp based on ETs, weight and speed. Not sure on torque.

Car runs high 13s, with a best of 13.7, 96-97 MPH.
60 foot times of 1.9-2.0

I spoke with Protorque about my set up, wanting to get the car out of hole better. Car is driven to shows and cruise nights, not concerned with gas mileage. When I go to the track it’s trailer so I’m not driving it for long periods over the open road. I told him I want to get the most out of what I have, so he recommended the 9.5 pro drive model, 3500-3800stall. They make them in 2800-3200, 3200-3500too. He told me that if it’s too loose after a few runs, they will adjust it back at no charge (just my labor and shipping, ugh) but I’d love to avoid that. He said the modern converters they build are not like ones of old. It will be very driveable when cruising down the road at normal speeds. But when you mash the throttle, that’s when you’ll feel it.
For me the converter issue is kind of black magic, but guys I’ve spoke with said go with whatever they recommended.
I’m hoping someone maybe has a similar wght car and set up that can give me some feedback on what stall MAY work better for me.

 

[S10xGN]

A well built "small" converter drives great! I replaced the 12" "restalled to 3000" converter in my turbo-Buick S-10 with a Precision Industries "Vigilante" 9.5" 3200 stall and it not only drove way better but dropped the 60ft time from 2.2 to 1.7 and 1/4 mile time 1.3 seconds. You couldn't tell it from stock until you dropped the hammer on it...

Russ

 

[74GP455]

A well built "small" converter drives great! I replaced the 12" "restalled to 3000" converter in my turbo-Buick S-10 with a Precision Industries "Vigilante" 9.5" 3200 stall and it not only drove way better but dropped the 60ft time from 2.2 to 1.7 and 1/4 mile time 1.3 seconds. You couldn't tell it from stock until you dropped the hammer on it...

Russ

That’s what the guy at Protorque said to me, it will drive completely normal on the street, won’t even notice it, but when you mash it that’s when you feel it. I’m just questioning what stall I need? But I guess there’s no way to tell for sure unless it’s in the car. I just didn’t want to have to pull it back out to have it tightened up if necessary. But I gave him every piece of info I can, and this is what he recommended, I guess I should trust the pros?

 

[ExcellenceAuto]

This cam?
I can't believe they have it listed as running out of power at 4800... If this is true , you don't want too loose of a converter. But a rule of thumb is you want the converter to start to hook up when your power starts to come on... I'm no expert, others can explain it more fully. I'm just mainly wondering about the camshaft? Looks like it would make good power, but I can't believe it runs out of steam that early!

 

[74GP455]

The car pulls hard all the way to 5500 (haven’t pushed it past that rpm yet) so I think it has some power left after 4800. It goes through the lights around 5300 though. When I picked it, crower told me that the 455 will expand that power band some, so it prob is still making power past 4800.

This cam?
I can't believe they have it listed as running out of power at 4800... If this is true , you don't want too loose of a converter. But a rule of thumb is you want the converter to start to hook up when your power starts to come on... I'm no expert, others can explain it more fully. I'm just mainly wondering about the camshaft? Looks like it would make good power, but I can't believe it runs out of steam that early!

 

[ericnova72]

Your contact at ProTorque isn't lying, a "tight" small diameter converter like a 9.5" or 10" behaves nearly as well as a stock converter, only noticable slightly when running about using normal daily driver acceleration....but when you drop the hammer the car will come alive, and you'll forever be a believer in a custom built converter.
I know of guys driving 8" 4500-5000 stall on the street, and you would barely know it to hear them drive by, but watch out when that put the coal to it.

I have a custom 10" I bought more than 10 years ago, it was light years better than the off-the-shelf 11" TCI junk that was in there before....almost 6 tenths better in 1/4 mile of a low 12 second car(instant 11's ), and better street manners to boot. Lower transmission temperatures too, used to run up to 180-185° even with a big cooler, now it barely reaches 160°

 

[S10xGN]

The car pulls hard all the way to 5500 (haven’t pushed it past that rpm yet) so I think it has some power left after 4800. It goes through the lights around 5300 though. When I picked it, crower told me that the 455 will expand that power band some, so it prob is still making power past 4800.

My turbo truck never went over ~5800 with a 235" V6, the chip had a 6k limiter. Little truck ran 12.17 @ 115...

Russ

 

[chasracer]

My goodness (as Grandma would say) - why don't you talk to Neal Chance and have your current convertor re-worked for what you want. It's a heck of a lot cheaper ($200-$300) than a brand new custom built convertor and you still end up with a custom built convertor. We deal a lot with Abrussi and TSI - get them changed and tuned up when needed. I have one TSI that's been through the mill 3 times now - works great with the current combo.

 

[74GP455]

My goodness (as Grandma would say) - why don't you talk to Neal Chance and have your current convertor re-worked for what you want. It's a heck of a lot cheaper ($200-$300) than a brand new custom built convertor and you still end up with a custom built convertor. We deal a lot with Abrussi and TSI - get them changed and tuned up when needed. I have one TSI that's been through the mill 3 times now - works great with the current combo.

That would’ve been a good idea, but the converter is from the 90s, I didn’t think it would be an option. I wanted to go with something new, the technology seems to have changed a lot from them. It’s the last piece of my drivetrain to address. It’s not a complete budget crusher at $800, and I haven’t spent any money on the car this year. Just pushes my paint job back a few months, lol.

 

[chasracer]

There's not enough technology change in a normal GM convertor to worry about unless you want to go bucks-up with a bolt together unit. I have convertors that date back to the 80's at this point - no problems getting them updated but each to his own.

 

[ericnova72]

I would agree with Chasracer, you could have the Neal Chance at least looked at to see if an update is feasable. Chance builds good stuff.

i've had them reworked from other companies in the past, some converters I bought new and some bought off freinds or other racers and had them checked and restalled.
Couple times had supposedly "good" name converters opened up to find some really shoddy workmanship which lead to the discovery that the seller was less than honest about what brand they were....my converter guy had seen enough that he could tell me....one was the infamous GER out of Pennsylvania(out of business) and the other Fairbanks.
The GER got it's stall by way of every 4th fin pounded over flat with a hammer !!
Explains why it had 4000+ stall behind a pump gas 383 but never seemed to pull on the upper end of the rpm scale. LOL
Converter guy said it wasn't even worth welding back together but the guy I got it from would refund the mney if I returned the converter back "functional", so I paid to have it welded.

 

[chasracer]

Eric,
Yep my first "real race" convertor was one of those GER deals, a 9" unit that was supposed to be about 4500. The car was all over the place so I sent it to TSI to have it checked out and got about the same information. I told them to toss it and purchased a new convertor from them - been using a lot of their stuff since then too. I give GER one thing, I don't have any idea how much a two page spread in most of the car magazines was back then, but the magazines sure made out - at least for a while.