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LS SWAP mounts and brackets,, confused

12K views 28 replies 11 participants last post by  Dbl6gun 
#1 ·
I have a couple questions for you guys who have done this swap, I have a 72 chevelle, My 468 chunked a rod on the highway earlier this summer and I am just done with the big block turbo 400 setup. I am swapping in a stock LS3 with a 4l80 trans and controlling it with the Holley Terminator system. The problem is the more I read about the swap mounting components the more I get confused about the mounting. From what I keep reading Holley makes a set of adapter plates that bolt to the LS engine to use with the original motor mount pedestal, and then I read they make the pedestals that bolt to the engine crossmember that mount to an LS engine, some people use one or the other, or both? And to confuse even more I am reading of how some people bought mounts to move the engine forward, or raise the engine. I understand installations vary with vehicles. But now I am confused as to which parts to get. I would like to stay with 1 brand that way I know the parts work together. I am wanting to get the right parts to put this LS3 in my chevelle, using the holley pan for the swap, I am also installing a 4l80E, I am not sure if I will have to cut the tunnel, I am more than capable of that, but hoping I dont have to do too much and hopefully keep my factory console.

Can any of you guys help point me in the direction of what parts I need to install this so I purchase the right ones the first time? Thanks Fellas I appreciate any help/experience from those who have been down this road.
Ronnie
 
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#3 · (Edited)
Easiest way is to go Holley(I started my swap before Holley had all the parts). But yes you can do it differently. The stock crossmember mounts work with energy suspension short and wide engine mounts. That places the engine low and back nearly against the firewall.(right where I wanted mine.) I used AC delco corvette accessories, stainless TSP 1 7/8 f body headers(bought used but they hadn’t been installed) dirty dango smaller power steering pump pulley and a f body pan. This time around I used the Holley oil pan 302-3 for the stroker I built. The Holley fit much better. Don’t forget the front springs may need changed ls3 will be a couple hundred pounds lighter. 4l80 will need tunnel cutting. If you aren’t opposed to a manual the TKX fits perfectly without tunnel cutting.(besides the hole need to make it a manual car)
 
#5 · (Edited)
4l80 will need tunnel cutting
this is incorrect. We just did a super charged LS3 with a 4l80 in a ‘72 and didnt cut the tranny tunnel. We did beat the snot out of the tunnel with a rounded hammer to clearance the end of the tunnel where the 4l80 is fatter. But it fit with no cutting.

We used the complete hooker blackheart kit with cross member, engine frame brakets (clamshell motor mounts) and the “stock” or “rearward” mount brackets.

You will need Banjo fittings to get the lines hooked up on the 4l80.

I attached some pics of the 4l80 in the tranny tunnel. And also some of the banjo fittings. I have pics of the engine brackets (forward and rearward versions) too. I also have pics of what interference issues we ran into with the forward mount brackets. I’ll make another post with those and the part numbers of everything we used since you have the exact same setup as what we just did.

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#4 ·
Yes, all Holley for me. I'm running their 302-2 oil pan and their forward bias A-body engine mounts. These frame engine mounts mate up to a set of F-body Camaro mounts that bolt to the engine.

These mounts move the engine forward which eats up some fan clearance at the front but not much - electric fans required.

Then a set of Holley Hooker Blackheart headers for an A-body.

No problems with needing sheet metal surgery at the floor pan and at least with a 4L60E transmission, I was able to reuse my transmission cross member.

Your biggest problem will be managing enough clearance for the trans oil cooling lines. I had to use elbows immediately coming out of the transmission to clear the floor sheet metal.

Rick

Sent from my SM-G965U using Tapatalk
 
#6 ·
I stand corrected I guess you can install a 4l80 without tunnel modification. You just have to move the engine forward away from the center of the car.
 
#7 ·
that is also incorrect. When we got the car it had the 007 rearward brackets. We tried the 006 forward brackets but ran into clearance issues with the power steering pump hitting the steering box and headers hitting the k-member. We went back to the rear mount 007 brackets and thats when used a rounded hammer to clearance the tranny tunnel. The pics you see above with the tranny in are with the engine in the stock or “rearward” position.
 
#9 ·
How much clearance is between the heads to firewall?
 
#27 ·
1971 LeMans Sport. I did a LS3 EROD install in a 79 Trans Am
Personally I like the Holley components for the A body cars because everything works together, mounts, headers, exhaust, and cross member.
 
#29 ·
I have a couple questions for you guys who have done this swap, I have a 72 chevelle, My 468 chunked a rod on the highway earlier this summer and I am just done with the big block turbo 400 setup. I am swapping in a stock LS3 with a 4l80 trans and controlling it with the Holley Terminator system. The problem is the more I read about the swap mounting components the more I get confused about the mounting. From what I keep reading Holley makes a set of adapter plates that bolt to the LS engine to use with the original motor mount pedestal, and then I read they make the pedestals that bolt to the engine crossmember that mount to an LS engine, some people use one or the other, or both? And to confuse even more I am reading of how some people bought mounts to move the engine forward, or raise the engine. I understand installations vary with vehicles. But now I am confused as to which parts to get. I would like to stay with 1 brand that way I know the parts work together. I am wanting to get the right parts to put this LS3 in my chevelle, using the holley pan for the swap, I am also installing a 4l80E, I am not sure if I will have to cut the tunnel, I am more than capable of that, but hoping I dont have to do too much and hopefully keep my factory console.

Can any of you guys help point me in the direction of what parts I need to install this so I purchase the right ones the first time? Thanks Fellas I appreciate any help/experience from those who have been down this road.
Ronnie
This company has some good options and parts to consider for an LS Swap. I used them 5 years ago when I put a new LS7 crate engine in a 66 Sting Ray……. The swap went well!

MuscleRods 68-72 Chevelle LS Conversion Kit
 
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