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Discussion Starter · #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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Get with Holley and get a complete kit. And make sure you get the oil pan. They do make a few different mounts but the ones in the kit I believe you change out the frame stands.
 

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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)
 

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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

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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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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.
 

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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.
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.
 

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I really like the tranny cooling line adapters, very nice. Looks like it fits better then the 4L60 actually. I cut the bottom of my truck oil pan off even with crossmember and cut away what was left until it fit and had it welded up.
 

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How much clearance is between the heads to firewall?
i think about an inch. I prefer the look of how the engine sits closer to the firewall with the rearward brackets. When we tried the forward brackets, it ended up bringing the motor another inch away from the firewall and it just looked like it sat too far forward.

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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.
Something must be different than on the '67 frame. On my '67 have had both sets of holley mounts and both allow the 1 7/8 blackheart headers and pump to clear. I'm using the GM modified corvette accessory drive for an LSA and ended up using the forward bias mounts to allow the early CTSV A/C compressor to clear the frame cross member.
 

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Something must be different than on the '67 frame. On my '67 have had both sets of holley mounts and both allow the 1 7/8 blackheart headers and pump to clear. I'm using the GM modified corvette accessory drive for an LSA and ended up using the forward bias mounts to allow the early CTSV A/C compressor to clear the frame cross member.
67’s are different. The setup im referring to is for 68-72 A-Body
 

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67’s are different. The setup im referring to is for 68-72 A-Body
You used Hooker blackheart headers with the Holley forward biased mounts and the headers didn't clear the front cross member? That seems odd since Holley states that the headers work with both the forward and rear biased mounts. What header part number did you use?

Also what accessory drive are you using?
 

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You used Hooker blackheart headers with the Holley forward biased mounts and the headers didn't clear the front cross member? That seems odd since Holley states that the headers work with both the forward and rear biased mounts. What header part number did you use?

Also what accessory drive are you using?
Yes you are correct. The headers hit the k member when we used the forward biased 006 HKR engine brackets. Not sure what the exact headers are. I know they are the holley Hooker Blackheart LS swap series. Just dont know the exact part number as we took this project over from another shop. They had the documentation missing for the headers, but had documentation on the rest of the kit (engine brackets, motor mounts, tranny cross member and tranny mount)

We are using the cvf racing serpentine kit for LS3 and edelbrock e-force super charger. They only make one kit that fits an LS with edelbrock e-force supercharger. It has a remote reservoir power steering pump setup. When we pulled the motor forward to use the 006 brakets, it put the power steering fittings right up against the steering box. And thats after we re-clocked the power steering pump to even get it to sit right in the first place.

The car came to use with a 4l70. We upgraded to a 4l80 stage 3, 1100hp unit. When we tried to put the 4l80 in, it wasnt even close to fitting. Then we read that the 007 rear biased engine brackets (that were already installed on the vehicle) would require “extensive” cutting of the tranny tunnel. Thats when we tried the forward biased brackets. When we ran into more issues going that route, we swapped the 007 brackets back in. Then just beat the crap out of the tranny tunnel and got the 4l80 to fit with no cutting whatsoever.

rear vs forward mount (007hkr vs 006hkr) (you can see how they offset the holes)
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Rear mount 007hkr installed with 006hkr being held in place to show the mounting difference:

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Power steering fittings super close to the steering box with the 006hkr forward mounts installed:

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Can you show a picture comparing same side mounts? It appears you have a LH & RH shown by looking at the notch for the motor mount.
 

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Can you show a picture comparing same side mounts? It appears you have a LH & RH shown by looking at the notch for the motor mount.
that second pic from the last post is both the same side comparison. I dont have anymore pics like the first one above with both of the same side on the ground.
 

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I've done 2 swaps using all Holley parts, 70 Cutlass and 70 Chevelle. Never touched the transmission tunnel for 4l80e, forward frame mounts on the engine. Everything bolted up and driveline angles are perfect.
 

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Discussion Starter · #18 ·
GTO44

Thanks for all the detailed pics, this is exactly what I was hoping for, now I know which direction to go, That install is absolutely killer,,
 

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Good info. I have been thinking doing a ZL1 conversion
 

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Yes you are correct. The headers hit the k member when we used the forward biased 006 HKR engine brackets. Not sure what the exact headers are. I know they are the holley Hooker Blackheart LS swap series. Just dont know the exact part number as we took this project over from another shop. They had the documentation missing for the headers, but had documentation on the rest of the kit (engine brackets, motor mounts, tranny cross member and tranny mount)

We are using the cvf racing serpentine kit for LS3 and edelbrock e-force super charger. They only make one kit that fits an LS with edelbrock e-force supercharger. It has a remote reservoir power steering pump setup. When we pulled the motor forward to use the 006 brakets, it put the power steering fittings right up against the steering box. And thats after we re-clocked the power steering pump to even get it to sit right in the first place.

The car came to use with a 4l70. We upgraded to a 4l80 stage 3, 1100hp unit. When we tried to put the 4l80 in, it wasnt even close to fitting. Then we read that the 007 rear biased engine brackets (that were already installed on the vehicle) would require “extensive” cutting of the tranny tunnel. Thats when we tried the forward biased brackets. When we ran into more issues going that route, we swapped the 007 brackets back in. Then just beat the crap out of the tranny tunnel and got the 4l80 to fit with no cutting whatsoever.

rear vs forward mount (007hkr vs 006hkr) (you can see how they offset the holes)
Which balancer are you using?

I would venture the blackheart headers you received with the project weren't necessarily the ones that go with the holley mounts. Also the aftermarket drive system looks like it placed the power steering pump down lower and possibly out a bit compared to the GM corvette or LSA modified accessory drive.

FWIW - The forward vs rear mounts are about 1" different in the engine positioning due to the difference in the LS design crank/bellhousing mounting relationship. Basically the rear mounts place the LS bellhousing flange in the same position as the a SBC to allow for minimal changes if using a TH400/350 or Muncie. It keeps the transmission in the same location as it originally was.

The forward bias positions the rear of the LS heads where a SBC head would be. This pulls the trans forward whtich allows for better clearance when using a AOD tranmission such as the 4L80 but then you have to deal with the trans mount and driveshaft.

Here's a shot of the clearance between the power steering pump and the steering box on my '67 using the GM corvette accessory drive. Not a '68 -'72 but my understanding is the clearance is similar.

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