BUILD THREAD 1985 Grand Prix SBC 400 Swap - "Lady Sif"

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Highlord_Fox

Not-quite-so-new-guy
Sep 8, 2020
23
63
13
New York
I figured I'd start my own build thread here as well. I have a 1985 Grand Prix Brougham, originally with a 305 SBC & TH200R transmission that I'm rebuilding after letting it sit for nearly 20 years in my parents' yard.

This project is also being filmed as I go along, to which you can find the link to the playlist here. The playlist will generally have the same information I post here, in video form as well.

As someone in the tech field, I figured I'd apply TECHNOLOGY to this project. As such, I now have a Trello board for this.

Some background on this car: My mother had a mid-80's Grand Prix (V6) back in the early 90's, and when it was stolen, my father saw this one and bought it for her basically the same day. He wound up using it a lot, and it has a bunch of family history in it- He blew out the rear end by putting tiny 14" wheels on it, my brother shattered the driver's side window with a Snapple bottle as a toddler (which meant we got a new door as a door was cheaper than a window at the time), and I helped my father wire up a fancy (for the time) CB radio and antennae into the car. Sadly, in the early 2000's, the motor decided to grenade itself, and he made the decision to buy a replacement engine- A 400 SBC that was allegedly from a late 70's/early 80's truck. We tore the engine down and rebuilt it from the ground up, as the prior rebuilders did a piss poor job at it, and had to fix multiple issues they had created in the process. I have some fond (and some less than fond) memories of this rebuilding process that took place in my early teenage years, of rebuilding heads on top of our dishwasher, to accidentally setting the spark plug wires on fire when testing it, to sitting there inside the deafeningly loud headers-only car. Sadly, due to time and money, we never finished the project back in the early 2000's, in part because of leaking around one of the freeze plugs my father was not able to easily solve, and the car wound up sitting for nearly two decades, being occasionally hand-pushed across the yard from spot to spot to get out of our way.

Last year (2019), I finally approached my parents with an intent and offer to buy the car and get it on the road again, which they accepted. By the time that happened, it was too late into the winter to work on the car in the middle of a small field, so it was just this year (2020) that I got to working on it.

Some stats on the car, which are all as accurate as I can tell (due to the history of it, these may be subject to change as I learn more):
  • Came with a 305 V8 originally.
  • Replacement engine is a 1974 6.6L 400 SBC, out of a Chevy B-Wagon (I have presumed it to be a Caprice).
    • The casting code is CSY, which is very unique as far as I can tell. Several sites don't even have it on their reference charts.
  • Transmission was replaced before we got it, changing from a TH200R to a TH350.
  • The rear axle has been replaced, still working on researching what it came out of.
  • The driver's side door is a replacement, still working on researching what it came out of.
  • The dashboard has been modified to replace the basically useless giant clock with an actual tachometer.
  • The car is intended to (and will likely have) a set of 3" Hedman headers.
  • Carb is a 600 CFM Holley 4160 Street Warrior.
  • At this time, most of the interior & body (sans the driver's door) is original.
That's about it, as far as I can tell. I'll follow up with some pictures of it from last year and this year. Most of my documentation thus far has been via video, but I'll make sure to take stills of it going forward to share with everyone here.
 
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Highlord_Fox

Not-quite-so-new-guy
Sep 8, 2020
23
63
13
New York
This is the condition she was in at the end of last year, in the spot she had been sitting in for a few years now.
20190819_184411.jpg


She'd seen better days, and had weeds and thorn bushes growing up around her.
20190819_184419.jpg

I have some other shots of the downtrodded shape she was in:
20190819_184253.jpg


20190819_184216.jpg


And one money shot of the 400 SBC sitting in the engine bay, untouched and un-started for about 15 years.
20190819_184153.jpg
 
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Highlord_Fox

Not-quite-so-new-guy
Sep 8, 2020
23
63
13
New York
This year, she actually got a pressure wash (even if it's a half-assed job when viewed up close)!

20200525_200456.jpg


Then, a few months ago, I finally got a chance to move it to a better location! She's now sitting alongside my father's 73 Le Mans, a project car that has been sitting around since before my Grand Prix was even built.
20200717_190159.jpg


I have a slew of engine reference photos I've taken (for hose/wire/mount placement purposes),but I'll save you the effort from trawling through them. If anyone does want to see them, let me know and I can provide them. What I do have is a shot of the engine bay after the first day of stripping:

20200717_190220.jpg


Two weeks ago I spent some more time on it, pulling out the transmission-related bolts, the starter, the carb, the distributor, and basically getting it ready to be pulled. The last steps before I can yank the thing out are the two motor mounts, and then the hood.
 
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Highlord_Fox

Not-quite-so-new-guy
Sep 8, 2020
23
63
13
New York
lighten it up throw some good heads on it and spank it at ATCO:devilish::devilish:

Nah, she's going to be rebuilt into something I could daily drive if I wanted to, even if I don't because she's gonna get like 5MPG on a good day. Rebuilding it and getting it running was always in my family's plan, it's just that I have the time and money to do it now, instead of my parents (specifically my Mother). The engine is going to be pretty much stock (partially because I want this to be a 20 year car, and partially because I can't afford anything else otherwise).
 

Highlord_Fox

Not-quite-so-new-guy
Sep 8, 2020
23
63
13
New York
Speaking of the carbs, I rebuilt the Holley last week (and filmed it, so hopefully before the end of Sept I will have some level of detailed video on the process), and also cleaned off the air cleaner to remove as much of the rust and oxidation from it as possible. Neither are perfectly clean, but I'm going for more of a "worn in" look on the car (partially out of it being easier, partially because of time, partially because of money, and partially because it just needs so much work that I am willing to cut a corner or two in aesthetics if it means I can drive it that much quicker). I do have some pictures of that bit of work too.

Before:
IMG_20200829_152710_01.jpg


And after Cleaning/Rebuild (excuse muh feet):
20200909_185017.jpg
 
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1evilregal

Comic Book Super Hero
Apr 23, 2009
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Greensboro, NC
nice to see another GP coming back to life! I rescued "Chief" from sitting under a bunch of trees for 4 years, brought it home, and been driving/ working on it for coming up on 5 years now.
 
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Texas82GP

Just-a-worm
Apr 3, 2015
7,989
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Spring, Texas
Subscribed. I'll check the vids too. Are you keeping the 400? If so, are the heads drilled for the steam holes?

Are you staying with the TH350? A 200-4R with a 3.42 or 3.73 is a hard combination to beat for a cruiser.
 
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Highlord_Fox

Not-quite-so-new-guy
Sep 8, 2020
23
63
13
New York
nice to see another GP coming back to life! I rescued "Chief" from sitting under a bunch of trees for 4 years, brought it home, and been driving/ working on it for coming up on 5 years now.

Is that one of the builds in your sig?

Subscribed. I'll check the vids too. Are you keeping the 400? If so, are the heads drilled for the steam holes?

Are you staying with the TH350? A 200-4R with a 3.42 or 3.73 is a hard combination to beat for a cruiser.

I am keeping the 400, as long as I can fix the issue with the block and its freeze plug leak/sealing. I can expand more on that when I have the engine itself out. And yes, I will likely be keeping the TH 350 in it- Mostly because budget demands I do. I don't know what the rear end gearing is yet, but my first goal is to get it back on the road, and then if I need to make alterations and adjustments I will.

I also have no idea about the heads. As far as I know, they are the stock heads from 1974. When we pulled them off last time, I don't think we knew to check for them, but I will certainly check and post pictures of them once get them off. I have a full set of ARP bolts to go in this time.

Another YouTube star, huh?

Yeah, watching a few of my favorite channels, combined with my urge last year to go "Yeah, I want to do this project", lead to that. It's also an interesting hobby, and a fun learning experience in filming and editing. But for all ya'll, I'll make sure to take plenty of pictures. =)
 
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