8" ATI converters on the street....? - Chevelle Tech
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post #1 of 50 (permalink) Old Jul 8th, 19, 5:40 PM Thread Starter
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Alan
 
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8" ATI converters on the street....?

Anyone running a custom spec'd ATI 8" converter in their street car and actually put any miles on it? Any thoughts / opinions on this converter?


There is a chance I may be pulling my trans out to replace the shift shaft detent seal that's leaking...if that happens, I'll likely have the whole trans refreshened, which would be the perfect time to change converters.

I'm thinking about getting one of Mark's custom spec'd ATI converters, I'm just concerned it would be too loose for as much as I drive my car, especially on long highway runs. I don't want it to be a sloppy mess around town or have no pick up off of corners etc.

My current 10" converter is excellent on the street, but it weak sauce on the track. Flashes about 3500-3600 from idle launches, and about 1100 rpms worth of shift extension...(rpms drop to 5200 ish on shifts). Goes through the traps at 5900 ish. This is at 3700lbs race weight, 3.36 gears, 27" tires. Current 60' is 1.51-1.52.

I'm thinking another 1000 or so rpms worth a flash stall would REALLY wake this thing up, I just don't want to hurt the driveability TOO much...

Looking for input from anyone that has owned/driven a custom spec'd 8"... Thanks!

1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
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post #2 of 50 (permalink) Old Jul 8th, 19, 8:41 PM
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Re: 8" ATI converters on the street....?

Call Lenny at Ultimate Converters, He will set you up with a really tight converter that will stall to 5500 if you need it. Lenny is the man.
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post #3 of 50 (permalink) Old Jul 8th, 19, 10:04 PM
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Re: 8" ATI converters on the street....?

I ran a Coan 8" converter for several years with my 357 nitrous setup. I then went to a 9" Coan with a 427SBC on nitrous and now an ATI 9" with the F2 Procharged 427. Cruising in town or on the freeway they all worked great. As soon as I go full throttle it will flash to 5,500 but again has no problem cruising at 3,000 on the freeway.
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post #4 of 50 (permalink) Old Jul 8th, 19, 10:21 PM Thread Starter
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by Steve69SS396 View Post
I ran a Coan 8" converter for several years with my 357 nitrous setup. I then went to a 9" Coan with a 427SBC on nitrous and now an ATI 9" with the F2 Procharged 427. Cruising in town or on the freeway they all worked great. As soon as I go full throttle it will flash to 5,500 but again has no problem cruising at 3,000 on the freeway.

I just went for a ride in Rafel’s 67” Camaro that runs 9.70s with a 420” SB, he runs an 8” ATI converter spec’d by Mark Jones. The car drove better then I thought it would, it’s definetly loose though. I could probably live with it if it drove like his, however his car is 3000lbs and has 4.10 gears... I have a feeling an 8” in my heavy car with 3.36s would be WAY too loose.
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1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
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post #5 of 50 (permalink) Old Jul 8th, 19, 10:45 PM
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Steve
 
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by ShouldntBeHere View Post
I just went for a ride in Rafel’s 67” Camaro that runs 9.70s with a 420” SB, he runs an 8” ATI converter spec’d by Mark Jones. The car drove better then I thought it would, it’s definetly loose though. I could probably live with it if it drove like his, however his car is 3000lbs and has 4.10 gears... I have a feeling an 8” in my heavy car with 3.36s would be WAY too loose.
My car weighed 3,420 with the 357 and now weighs 3,500 but It does have 4.10 gears. With your taller gears and more weight it will feel looser.

'69 Camaro - 429 SBC Dart Iron Eagle 9.325" block, Crower crank, Crower 6" Billet rods, Ross pistons (10:1), Total Seal S/S rings, AFR 245 heads, T&D steel rockers, Cloyes Timing Set, 4-7 swap solid roller 274/286 @ .050", .704" lift, Dart single plane, Dominator EFI, Stef's #1705R pan, F2 Procharger on E85
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post #6 of 50 (permalink) Old Jul 8th, 19, 11:07 PM
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Re: 8" ATI converters on the street....?

Somewhat of a topic drift, but you can easily replace the shift shaft seal with the transmission in place. Napa sells the puller/install tool for about $5.00.

Back to converter talk....
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post #7 of 50 (permalink) Old Jul 8th, 19, 11:12 PM Thread Starter
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Alan
 
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by any4xx View Post
Somewhat of a topic drift, but you can easily replace the shift shaft seal with the transmission in place. Napa sells the puller/install tool for about $5.00.

Back to converter talk....

Thanks. I looked into it. It seems you have to pull the valve body out to replace the seal because the shift shaft is attached to the VB. Pulling the VB out with the trans in the car seemed a little worrisome to me. I could just see check balls and springs falling out all over my garage floor. Lol

1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
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post #8 of 50 (permalink) Old Jul 8th, 19, 11:17 PM Thread Starter
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Alan
 
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by Steve69SS396 View Post
My car weighed 3,420 with the 357 and now weighs 3,500 but It does have 4.10 gears. With your taller gears and more weight it will feel looser.

Yeah my car is about 3720lbs or so in street trim...maybe a little more. And with 3.36 gears and 28” tires, I’m afraid the 8” would be too loose.


I could always build another 10”...but I really wanted to try the 8” for the spinning weight reduction and efficiency on the big end.


I had a 9.5” in my C5Z that went 5400 on the trans brake, would flash to 5200 from a foot brake launch, and it drove great around town....however that car had a LOT more power to make it flash at wot. (850 rwhp). And it would lock on the highway... best of both worlds.
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1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
STOCK APPEARING
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post #9 of 50 (permalink) Old Jul 9th, 19, 1:43 AM
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Re: 8" ATI converters on the street....?

If I'm not mistaken Mark drives/has driven an 8" converter on the street as well. I'm sure you've already talked to him about it, not sure how long his hauls have been though.

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post #10 of 50 (permalink) Old Jul 9th, 19, 7:41 AM
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by ShouldntBeHere View Post
Thanks. I looked into it. It seems you have to pull the valve body out to replace the seal because the shift shaft is attached to the VB. Pulling the VB out with the trans in the car seemed a little worrisome to me. I could just see check balls and springs falling out all over my garage floor. Lol
I guess we’re talking about two different seals. TH350/400 seals just knock on from the outside of the case with no disassembly.
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post #11 of 50 (permalink) Old Jul 9th, 19, 8:31 AM
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by aukai View Post
If I'm not mistaken Mark drives/has driven an 8" converter on the street as well. I'm sure you've already talked to him about it, not sure how long his hauls have been though.
My every day driver has this 8 inch converter in it. 4200 pound C-10 truck, steel wheels, two piece drive shaft, open 3.07 gears, 30 inch tall tires, locked dist as well. And it does everything you mentioned-------and I love it. 12 sec 327 street truck in Houston. And with gears and a spool your looking at 11s. Road Kill Killer.
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post #12 of 50 (permalink) Old Jul 9th, 19, 8:57 AM
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Re: 8" ATI converters on the street....?

Ran an 8" custom Coan converter around the streets for years...
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post #13 of 50 (permalink) Old Jul 9th, 19, 5:55 PM Thread Starter
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Alan
 
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Re: 8" ATI converters on the street....?

Quote:
Originally Posted by any4xx View Post
I guess we’re talking about two different seals. TH350/400 seals just knock on from the outside of the case with no disassembly.



Yes I'm talking about the seal on the shift shaft from the valve body to the shifter linkage/cable. Probably some kind of lip seal or o ring. Maybe if I removed the linkage I could slide the seal out over the shift shaft from the outside but...I doubt it, at least not without dropping the trans down. There is no room in there.


Pretty much made my mind up to pull the trans, refreshen it, and get a 8" converter from Mark.


The trans still works great but, its 10 years old and has 26k miles on it...LOTS of passes on the street/strip.


Mark, I'll call you tomorrow if you see this.


Maybe this ole jalopy will run some 10.20s with a real converter...

1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
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post #14 of 50 (permalink) Old Jul 9th, 19, 6:00 PM Thread Starter
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Re: 8" ATI converters on the street....?

Here is today's puddle with the new cork pan gasket, after only a 30 mile highway drive. I'm gonna jack it up tomorrow and look at the shift shaft area real close but...my guess is that's the culprit...not the pan.





All of this was clean as could be yesterday before I drove it so...its a significant leak for sure.

1971 Corvette
VortecPro 496"
T400, Tight 10" converter
3.36 gears, 3700lb raceweight
[email protected], 1.51 60'
STOCK APPEARING
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post #15 of 50 (permalink) Old Jul 9th, 19, 6:55 PM
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Eric
 
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Re: 8" ATI converters on the street....?

Do it.

I got an 8" ATI from Mark and in my 3900+ lb. Chevelle with 600+ HP/TQ and 3.73's, it's 100% tolerable on the street. Under light throttle it behaves like a typical ~3000 converter.
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