Frame strength 1979 cutlass

Status
Not open for further replies.

PaulHrvth

Not-quite-so-new-guy
Dec 4, 2020
13
0
1
Hello I have a 1979 Cutlass TTop car and am planning to swap the 305 with a Blueprint 390 hp 350. Will the stock frame be OK. This car is rust free
 

Built6spdMCSS

Geezer
Jun 15, 2012
5,695
9,504
113
Florida Beach
Yea lol definitely will be fine.

Go For It GIF by KawasakiUSA
 
  • Like
Reactions: 1 users

ck80

Moderator
Moderator
Supporting Member
Feb 18, 2014
5,742
9,114
113
Depending how you plan to drive it that rear end may benefit from some upgrades or not last too long, but, frame itself can handle the job.
 
  • Like
Reactions: 2 users

Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,831
2,568
113
Galaxy far far away
First I would check the body mount bushings for dry cracking. If they are the originals from 79 they better be replaced to withstand that increased power. The frame is designed to be reinforced by the body bolted to it so you want good connections. Unless your car already has them you really should get F41 Jounce bars, a front GP bar is good idea too. Check behind the rear seat for a factory brace. If your car lacks the rear seat brace, plan on getting one. Its pretty easy to build a rear frame Jeff brace yourself from square tubing. Rear LCA mount braces aren't a bad idea either. Idealy by 400 hp the frame should be boxed.

G bodies in stock form are super floppy cars with limited HP capacity, they were originally designed to be granny cars afterall. 390 hp is pretty taxing on a unreinforced G body, only took 110 hp to crack the roof on my Regal. Good news is that a 70's model like yours has more bracing stock than the later 80's models which were victims of further downsizing.

The 7.5 rear is another can of worms when it comes to high HP, along with stock brakes.
 
  • Like
Reactions: 3 users

john87442

Master Mechanic
Supporting Member
Mar 9, 2021
305
327
63
Geneva ohio
I’m currently working on a 87 442 that I’m restoring and replacing the 307 with a 400hp olds 350. Now it has t tops also so im boxing the frame with a fx kit along with other braces in the rear. Hutch has a great video on hutch hiperf about adding a rear seat brace. Not expensive and definitely worth it. And definitely worth it to replace those body bushings.
 
  • Like
Reactions: 1 user

john87442

Master Mechanic
Supporting Member
Mar 9, 2021
305
327
63
Geneva ohio
Sure I’m currently welding in new body mount bushing washers where the frame had rusted out. Then I have to replace the two frame rails behind the rear wheels these are always trouble areas, but haven’t gotten that far yet. I don’t have a lot of pics now but will post more as I’m working through it.
 

Attachments

  • D9A270E7-988D-478D-A5B1-A678B3417F2B.jpeg
    D9A270E7-988D-478D-A5B1-A678B3417F2B.jpeg
    1.4 MB · Views: 76
  • 023A4292-CA9D-458D-B758-38F462F41903.jpeg
    023A4292-CA9D-458D-B758-38F462F41903.jpeg
    1 MB · Views: 75
  • A505386A-E95F-4A4B-BFE0-59C91B443C6C.jpeg
    A505386A-E95F-4A4B-BFE0-59C91B443C6C.jpeg
    1.1 MB · Views: 79
  • Like
Reactions: 3 users

Clone TIE Pilot

Comic Book Super Hero
Aug 14, 2011
3,831
2,568
113
Galaxy far far away
Sure I’m currently welding in new body mount bushing washers where the frame had rusted out. Then I have to replace the two frame rails behind the rear wheels these are always trouble areas, but haven’t gotten that far yet. I don’t have a lot of pics now but will post more as I’m working through it.

I had to weld a repair washer on passenger side #2 on my Regal. Very common rust out spot as the poirly designed HVAC drain dumps rain water all over that bushing.
 
Status
Not open for further replies.

GBodyForum is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. Amazon, the Amazon logo, AmazonSupply, and the AmazonSupply logo are trademarks of Amazon.com, Inc. or its affiliates.

Please support GBodyForum Sponsors

Classic Truck Consoles Dixie Restoration Depot UMI Performance

Contact [email protected] for info on becoming a sponsor