Opinions on Changes To Build

85Regal801

Not-quite-so-new-guy
Jun 13, 2022
29
13
Hello All,

So I have a 85 Regal with an LS2 swap, carbed and th400 I’ll post build below, my question is it was built for drag races but now since our drag track was closed and the closest track is too far away to make it worth it, I want to switch it up to a cruiser, be able to go on the highway to other car shows and cruises. So give me some opinions on how best to achieve my goal! Obviously I’m switching to EFI and adding power steering but as far as do I re gear the diff or swap trans???
Thanks!!

Build
1985 Buick Regal

Clean title

No rust

Ls2 6.0 (only had 30k miles when taken out)

less than 1500 miles on build

lq9 block

rings gapped

upgraded pistons

built th400 w/trans brake

switch panel for essentials

pc converter

prc heads

Holly 750 carb

Magna fuel 500 pump w/ sump tank

All arp head studs

Little John turbo cam

Kooks headers

Valve spring upgrade

Bigger oil pan

Trunion upgrade

Msd 6al with 2 step

Rear is a built 9 inch 35 spline axles 35 spool with

Strange disc brakes

GNX wheels
 

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Northernregal

Sloppy McRodbender
Supporting Member
Oct 24, 2017
3,334
113
Red Deer, Northern Montana territory
The cheap and easy answer is Ford 8.8 in the rear and a 4L80e with a flashed stock ECU. You could substitute in a Holley Terminator X-max for easier tuning and install.
 
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Texas82GP

Just-a-worm
Apr 3, 2015
7,731
113
Spring, Texas
What rear gear is in the car now?

A 3.42 rear gear and a 4L80E with a well matched converter to the overall setup makes a great all around package. A 3.08 might work with your TH400. What is your intended rear tire height? How fast do you want to be able to get down the highway? What is your tolerance level for the engine to be turning 3000+ RPM on the highway?
 
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Dayzedandkonfuzed

G-Body Guru
Feb 9, 2010
969
93
Anglemont, BC
Not sure what your gear ratio is, but being that it was built for drag racing I'm sure it will be too low for comfortable highway use. If you're only going to do one or the other, that would be the best bet I think. But as already stated, a 4L80E as well as a set of gears would be ideal, so as not to sacrifice much on the bottom end.

My Uncle has a 600hp+ big block, 3.23's, and a very built 700R4 with a lockup converter. He never uses the lockup as it drops the rpms down below 1000 at 55mph and just shakes the car down the road, but he claims 21mpg.

I agree that 3.42's with a 4L80E would be the ideal choice. If you're already running a 3.73, I would go the 4L80 route first, then swap gears if you're not happy.
 
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pagrunt

Geezer
Sep 14, 2014
8,230
113
Elderton, Pa
Pull the TH400, put in a TKX 5 speed & pick between stock or hydraulic throw out bearing. Then put something around a 3.73 out back with a LSD.
 
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85Regal801

Not-quite-so-new-guy
Thread starter
Jun 13, 2022
29
13
I don’t remember if the top of my head exactly the gear ratio but yeah the goal is no longer drag just straight cruising so I’d like for it to not scream like it’s falling apart at 70mph lol I’ll look into the 4l80 and what’s needed to make it work in a gbody I appreciate all of your guys’ input. I wanna start getting parts ordered. Hopefully I can sell the trans and recoup the cost haha
 
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ck80

Comic Book Super Hero
Feb 18, 2014
4,649
113
Bear with me, at first this may sound like a d*ck answer....

I vote sell the whole driveline and build something you like, that's unique to you. And you'll enjoy.

For example: you said you are looking at fuel injection... so you're already rewiring. You're looking at swapping trans, and at least gears if not rear end.

So.... why not find someone to take for a ride who wants to buy the whole shebang from you, engine/trans/rear to install into something they're building?

For street and around town nothing beats a big block rumble, preferably an ol buick 455 from one of the big cars that you warm up a little bit. Much more interesting show material as well as a conversation starter that stands it of the sea of ls swaps out there. And the old bop v8s can get modern FI just the same as any chevy.
 
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Dayzedandkonfuzed

G-Body Guru
Feb 9, 2010
969
93
Anglemont, BC
For street and around town nothing beats a big block rumble, preferably an ol buick 455 from one of the big cars that you warm up a little bit. Much more interesting show material as well as a conversation starter that stands it of the sea of ls swaps out there. And the old bop v8s can get modern FI just the same as any chevy.

Big blocks FTW.
 
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64nailhead

Goat Herder
Supporting Member
Dec 1, 2014
5,119
113
Upstate NY
You can use the rear end, but you ought to get rid of the spool. Look at Quicks performance for a clutch style posi and new axles to fit the posi spline. That would be cheaper and easier than getting another complete assembly.

Regarding the transmission. A TH400 will work just fine perhaps, repeat perhaps. It depends on how it's built. You should know if it's harsh shifting from driving it. You mentioned a PT converter. I assume you meant a PTC. If it is a PTC, then that's a quality unit that could be re-stalled for a more street friendly amount of slip, or it might work just fine on the street already - again, it depends on how it was built. But re-stalling is pretty inexpensive. An OD, like a 4L80, would be great, but not cheap between the transmission and the controller to run it.

Regarding the carb and MSD box (yikes - I've never understood doing this to an LS, but that's me). It would be a super easy conversion to a Holley Terminator TB or Sniper TB setup, but another $1000-1500 of money. Putting a multiport on it can be more expensive if you want an aesthetically pleasing intake.

And I can't disagree with ck80, selling the entire driveline to someone 'in the know' of what it is might offset the expense of swapping . Or just swapping the trans and rear.


Personally, with being cheap the main target (because I am), I'd 'run what ya brung' and put a Holley on it with a Terminator Stealth TB with the MSD, different differential, gears and axles. That should be in the $2500ish range. We are all very good and spending your money haha. Do you have a budget for this project?
 
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