Scuncio Chevelle ex-L78 - Page 16

**Donnie** · #**151** 10-19-2022, 07:24 PM

post a pic of the converter both sides.

TomN · #**152** 10-20-2022, 11:31 AM

Thanks Donnie. Converter is in the car now - so when I get the car back home from the mechanic's house, who is doing the work for me, I'll see what pictures I can come up with

I believe from what I remember the trans is from a 1970 or 71 Impala (from the trans code on the side of the case). Also the shifter lever is for a column shifter - we are swapping that out this week for one for a floor shifter.

**Too Many Projects** · #**153** 10-20-2022, 12:44 PM

If the converter is still from the Impala, it's not going to work with the L78 cam, as you are aware of. You'll need a converter to match the application, with a higher "stall" speed, either a rebuilt original or an aftermarket tuned to the cam.

TomN · #**154** 10-20-2022, 01:55 PM

Thanks Mitch. Yes you're right. I need a converter that will let the engine idle higher in gear - but I don't want a real high stall converter either. I enjoy the Pure Stock Muscle Car Drags and would need a converter that wouldn't blow-off F-70-14 tires.

But if I understand correctly - the stock converter did let the engine idle at about 750 rpm's and had a 2,200? rpm stall

**Mr70** · #**155** 10-20-2022, 02:20 PM

Quote:

Originally Posted by TomN

But if I understand correctly - the stock converter did let the engine idle at about 750 rpm's and had a 2,200? rpm stall

Yes,as that's what my L-78 TH-400 transmission lets it idle at.

**WILMASBOYL78** · #**156** 10-20-2022, 10:43 PM

Quote:

Originally Posted by Too Many Projects

If the converter is still from the Impala, it's not going to work with the L78 cam, as you are aware of. You'll need a converter to match the application, with a higher "stall" speed, either a rebuilt original or an aftermarket tuned to the cam.

The idle aspect is only part of the transmission issue...the hi-perf trannys used behind the L78 were special built units. They had stronger internals, the 6 lug high stall converter, a hi shift point governor and other unique features. There was an old thread about this, not sure if the info is still accessible.

https://www.yenko.net/forum/showthre...ighlight=trans

TomN · #**157** 10-21-2022, 01:49 PM

Thanks for the info on the transmission. Right now the trans seems fine, I'll know more soon as the car is getting close to being drivable

TomN · #**158** 10-21-2022, 08:49 PM

And the new Disc Brake Hold Off Valve leaks ..... so I've ordered another one

The transmission in my car has a "CR" code with a black tag - no picture, but the torque converter only has 3 bolts.

**WILMASBOYL78** · #**159** 10-22-2022, 01:10 AM

Quote:

Originally Posted by TomN

And the new Disc Brake Hold Off Valve leaks ..... so I've ordered another one

The transmission in my car has a "CR" code with a black tag - no picture, but the torque converter only has 3 bolts.

For 70-71 the 'R code' TH-400 would be a 454 application from a Chevelle...

The 3 lug converter indicates a low-horse option...

TomN · #**160** 10-22-2022, 04:04 PM

That's what I was thinking - but no way to know IF the trans has been up-graded without taking it apart, and I don't plan to just do that with the trans working good.

But the converter has to be changed