BUILD THREAD Grand prix LS1 build

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85GPLef41

Royal Smart Person
Nov 14, 2008
2,210
63
Colorado
Well, after a lot of procrastinating and excuses i have made some headway in my GP's never ending evolution. Since i have been a member i took out the stock 305, installed a Targetmaster 350, now its going on the 3rd one which you all know it's a 99 LS1 from a Firebird Formula T.A. It is also getting a host of goodies from the list on my sig. I installed the LS1 this morning using the poor fitting trans dapt 4595 plates and factory clamshells. I grinded down the plates down so they could sit right on the block and shortened 2 bolts cuz they were contacting the block webbing. Other then that it went in easily, and oil pan clearance was good along with the valve cover hitting the heater box. Only issue i have right now is the alternator wouldn't clear the plates, SO i am thinking of installing either Speedway's alternator relocation bracket or swapping the accessory drive to a Vette setup. Here are some pics this will probably become a build thread somewhat. I have a few pics as well in my photobucket account.
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LS1GN

G-Body Guru
Aug 7, 2011
600
0
Central Florida
GP is lookin awesome so far. Yours looks like it is in about the same place as mine - as far as location. Your steering shaft is out?

Clearing the steering box was a biggie for me because I run the truck accessories.
 

LS1GN

G-Body Guru
Aug 7, 2011
600
0
Central Florida
It seems like some people stress over getting the engine in the "stock" location. I guess they want to re-use the driveshaft.

I just tried to get the motor as far back as possible, and spent the $175 and got my driveshaft shortened.
 

Dr. Rudy

Greasemonkey
Mar 19, 2011
160
0
Pennsylvania
looks good, this is definitely a swap id like to do someday. cant wait to see when shes done.
 

motorholmes

Master Mechanic
Oct 1, 2007
375
16
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Yeah the trans dapt 1" back adapters suck. I think the '78 might be a little tighter than your '85. I had to shave the coil pack boss and the edge of the valve cover. I also have to relocate that coil about 1" offset. But I run truck accessories and have probly 1/2" clearance on my PS pump, so no problem there. The picture makes it look tighter than it is. Probly 1/4" on the heater box. I'm going to chain the engine so it doesn't rock too much.

The a/c and alt bracket fabrication starts this weekend. I didn't know Speedway has a bracket.. I'll check it out
 

Csilvy2000

Greasemonkey
Mar 14, 2012
249
28
Texarkana, AR
Your build is at the same point as mine. I have a '79 hurst/olds. I'm dropping a '06 4.8 and 4l60e combo in. I'm wondering what you used as a transmission crossmember? A lot of people run the G-force after market cross members. I looked for a cheaper route. I pulled a crossmember from a 1985 merc grand Marquis and trimmed 2inches off each side. The passenger side fit on a factory mounting pad and the driver side fit inside the frame. That part of the frame is somewhat flimsy so an additional piece of metal was tacked in.

Are you tackling the wiring on your own?

Good luck on it.

The truck mine came out of was averaging 17-21 mpg. That's an EXT cab 2wd 1/2 ton. I'm hoping with a good tune and bone stock set up, maybe some high 14 quarters and maybe 24 mpg.

I'm currently trying to figure out my fuel system. I have the whole truck and I would like to use as many parts as possible. This includes the factory fuel pump. My temporary idea is to mount the truck tank in my trunk. Yes, it fits but the groceries are going to have to go in the backseat.
 

motorholmes

Master Mechanic
Oct 1, 2007
375
16
I don't know about this- I'd have to add an idler to get more belt contact on the crank pulley
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I have some plug wires if you want em, they're too short for my truck coils. MOROSO 8mm
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RO86SS

Greasemonkey
Jun 10, 2009
124
0
tampa,fl
what do you have in mind for your harness.
 

85GPLef41

Royal Smart Person
Thread starter
Nov 14, 2008
2,210
63
Colorado
Thanks, the steering shaft is out as i'm also in the process of installing the under dash vents and will probably be installing another dashboard. I mocked up the up Jeep steering shaft and it seems to clear the factory manifolds fine. I also need to shorten the driveshaft to accommodate the 8.5 so it sitting back a inch back wasn't an issue.

I thought i was going to have to remove the heater box heat shield so it would provide clearance but once it was in it has about a half inch or so. As for the trans crossmember i am going to mock up the 4l60e and see where my crosmember fits and see if i can make it work. If not i have Iceman or a G force crossmember, Who has one? and any issues with it fitting especially with the setback plates.


As for the wiring i have a few companies in mind, I have to keep most of my emissions components hence the factory manifolds and cats, I will need to install the AIR system EGR, EVAP, o2's ETC ETC :| There is a company near me called fuel injection connection that seems to know what i would need to pass the state inspection. Also know a dude on Pro-touring.com that can help and has given me a good price.
 
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