Dissapointing results switching to 7" converter

[Mark Yacavone]

Kevin,
I've been avoiding this one, hoping someone else would handle it.
You are pretty much correct in your analysis I believe.
The theory behind the 7" is #1, lighter weight, which is always good,
and # 2, to be able to achieve a higher stall without having to bend the pump fins into much of a negative configuration.
Now, seeing the stator is actually physically smaller than the 8" Opel style unit, you are going to have a hard time getting a fabricated 7" stator to be able to multiply the same amount of torque as the 8".
Remember, at the approx. 2 to 1 multiplication ratio , the more torque you start with, the more you'll have after the converter.
If your car is in the middle of the pack now ( not necessarily yours personally), you can see where the problem lies.
There are still plenty of top qualifying SBC cars that are still using 8" converters.
If your car is not there yet, you'd be wise to spend your money elsewhere right now.
The 7" converter is not going to be the magic bullet you're looking for...in my opinion.

[Bob Gullett]

We tried a 7 inch convertor in my wife's GT/JA 85 Cutlass 327/250 PG. Back to back with our normal 8in convertor it lost a tenth. Flashed 200 RPM more that the 8 inch. We found the convertor was falling back on the flash point when it shifted. We lost a few hundredths in 60 ft as well.

[Dragsinger]

Kevin,

I just when through the discovery process of 7" vs 8" with the Super 10. My final decision came after talking at length with Gary Hettler and Charlie Plott with ATI.

ATI built me a high stall, mechanical diode 8" converter that is the cat's meow

[Ed Wright]

I have two friends that went to 7" converters in their SS/GT carbureted cars. Already fast, sorted out cars. Both picked up everywhere. I decided I had to have one of those!
Two 7" iterations later, my 8" ATI was still quicker and faster. Depends on the combo, like many other things. Or, I'm doing something very wrong. A strong possibility. LOL
LT1 SS car, 3 speed.

[Kevin Panzino]

Thanks for all the replays guys. We seem to be seeing a pattern here.
Hopefully the converter supplier will work with me on exchanging it for an 8"....I would certainly hope so since he recommended the 7"....

[S/ST 3040]

Originally Posted by Ed Wright

I have two friends that went to 7" converters in their SS/GT carbureted cars. Already fast, sorted out cars. Both picked up everywhere. I decided I had to have one of those!
Two 7" iterations later, my 8" ATI was still quicker and faster. Depends on the combo, like many other things. Or, I'm doing something very wrong. A strong possibility. LOL
LT1 SS car, 3 speed.

Could race weight and RPM range of the two examples be factors in the 7" converters working? Thanks

[FED 387]

7 inch convertor typical stall is in the 6000-9000 RPM range

8 inch convertor typical stall is in the 4000-7000 RPM range


Where is your peak power? If its in the lower end of those ranges a 7 will not help you

[Ed Wright]

Originally Posted by S/ST 3040

Could race weight and RPM range of the two examples be factors in the 7" converters working? Thanks

I'm thinking so. Both lighter cars, both with Quadrajets, both rev higher than mine.