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70 A-body LS swap question about cutting tunnel

 
Old 06-28-2019, 11:07 AM
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Default 70 A-body LS swap question about cutting tunnel

Guys, this project has been lingering for 7 years now and I'm trrrrrrrying to figure it out to finalize it.

> LY6 / T-56 are mounted and ready.
> My trans tunnel is cut out to the mid point of the cabin just behind the shifter.
> I've got a Chevelle TH400 mount in there with the plate cut off and flipped and rewelded on.
> I've checked downward angle at output shaft = ~-3 degree's to -4 degree's.

So far I think I'm in the green here on this phase.

WHere I've come into a problem, the 2nd half of the cabin it looks like the driveshaft
will not clear that middle hump to the rear seat. So I have to cut it, and reweld a new
mild hump in there like I've seen many conversions with this. My only concern is the reinforced
areas under the body, cutting these, I'm wondering how to I reinforce them again ???

Anyone have any ideas how to do this, or if cutting these will be detrimental ??
Obviously GM put them there for a reason, I'm just trying to figure out my options.

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Old 06-28-2019, 11:21 AM
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I found an article showing some custom body cross braces fabricated and installed
I'm assuming this will have to be 100% custom fabricated.....

https://www.hotrod.com/articles/0703...nnel_enlarging
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Old 06-28-2019, 03:28 PM
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Good to see you're back at it.
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Old 06-28-2019, 05:50 PM
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Default Tunnel

What motor mounts are you using? I have the Holley mounts and cross member in my 1970 GTO with my LS3/T56 and clearance in fine. Having the engine and trans located properly in an A-body is and must for proper driveshaft angle. I have a 9Ē which also helps with the DS Angle.
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Old 06-30-2019, 10:48 AM
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Originally Posted by 968ls1 View Post
What motor mounts are you using? I have the Holley mounts and cross member in my 1970 GTO with my LS3/T56 and clearance in fine. Having the engine and trans located properly in an A-body is and must for proper driveshaft angle. I have a 9” which also helps with the DS Angle.
Chevelle mounts, with a spacer plate, and F-body oil pan, and Chevelle trans cross member cut and rewelded the plate.

I've seen this setup work in other people's swaps before I chose this route, but the more I get into it, the more I'm debating just buying the Holley products.

Do you have pics of your progress in the build and what it looked like after it was complete I can roll thru for my own benefit ??

I completely forgotten what mounts are on the engine itself.......energy mounts IIRC, but I forget the #

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Old 06-30-2019, 12:38 PM
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Really hard to beat the holley stuff for simple. Its bolt in and go..

I ended up building a new trans tunnel from the back seat to the firewall, along with modifying the floor braces, because I wanted the engine as far back as possible, and the trans output high, to keep the driveshaft angles ok
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Old 06-30-2019, 02:20 PM
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My engine is back as far as possible and as low as possible with the Holley pan. I built all of my mounts myself, and my driveline angles are great. I didn’t have to cut the floor brace your refering to in my car. I have pics in my build thread in my sig. The Holley mounts are awesome and really do keep it all simple. I just like to build stuff.
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Old 07-02-2019, 11:37 AM
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You should get the tranny up another degree or so. -3/-4 is not that great. If it were me I would rather have it at -2.
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Old 07-02-2019, 03:38 PM
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Originally Posted by Smitty454 View Post
You should get the tranny up another degree or so. -3/-4 is not that great. If it were me I would rather have it at -2.
Agreed (presumably this is relative to the frame), especially if the car is going to be lowered in the rear. The Holley mounts put the engine as low as possible in the front, which improves the driveline angle situation.

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Old 07-02-2019, 06:01 PM
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I used 3/16 steel plate where i cut through those same kind of braces, made a new bridge for front seats, holds about 550lbs of fat guys just fine

doubled as shifter mount

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Old 07-02-2019, 06:35 PM
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I think I'd get rid of whatever that spacer is under the mount to start and get a better fitting oil pan. Then I'd stop using photobucket. There are tons of us with similar setups who did not have to cut that reinforced area out, seems like it would just be easier to get proper mounts and trans crossmember. I guess the options are keep guessing and hoping things will work of just buy something that does and be done with it. Having done it both ways the latter is preferable IMO.




[/QUOTE]
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Old 07-03-2019, 09:01 AM
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The only way to divorce yourself from the geometric fitment limitations imposed by the use of the factory engine stands (the installed engine height in your case here) is to use a mounting method that is specifically designed not to use them. The engine mounting brackets within the Hooker Blackheart A-body LS swap systems are one such example of this. Get rid of the frame stands and your frustration level will be greatly reduced and the quality of your installation will be greatly improved. Optimizing the engine position in an A-body LS swap requires the use of specific oil pan geometry in order to clear the inner tie rod ends and the back of the engine crossmember. This required fitment geometry is not present in any stock GM oil pan and so the Hooker Blackheart A-body swap systems were developed to capitalize on the minimal fitment profile of the Holley 302-2 and 302-3 oil pans. Here's a few images that will allow you to depict what I've described here.




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Old 07-07-2019, 11:32 PM
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Originally Posted by Aceshigh View Post
Chevelle mounts, with a spacer plate, and F-body oil pan, and Chevelle trans cross member cut and rewelded the plate.

I've seen this setup work in other people's swaps.

This is how I did mine...(5.3\T56 combo) 1" setback plates with a 3/16" plate under the motor mount for proper tie rod clearance.



Originally Posted by Che70velle View Post
I built all of my mounts myself, and my driveline angles are great. I didnít have to cut the floor brace your refering to in my car. I just like to build stuff.

Same here. Opened the tunnel up about 2" when I replaced the floor pans. But didn't have to touch the "brace".



Originally Posted by chuckd71 View Post
I think I'd get rid of whatever that spacer is under the mount to start and get a better fitting oil pan. Then I'd stop using photobucket. There are tons of us with similar setups who did not have to cut that reinforced area out, seems like it would just be easier to get proper mounts and trans crossmember,

Chuckd71 is right...In your situation, I'd maybe start over also. (And he's also right about photobucket...eff them.)
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Old 07-08-2019, 05:29 PM
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You can also solve driveline alignment issues by using a CV driveshaft fro The Driveshaft Shop. This is what I did in my GTO, because when I first did my swap, the Holley mounts and pan were not available, and at the time, I did not want to redo my whole swap.

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Old 07-10-2019, 11:46 PM
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Hi all, jumping in in this as I am about to ls3 swap my 65 malibu. Is the agreed consensus to use the holly mounts. I’ve heard dirty dingo and hooker recommended but those were old posts. I plan on running a tko 600. My donor engine is a built ls3 that has a 2002 Camaro oil pan? Will that pan work if I use the Holley mounts? If not, holly offers multiple pan options, what the part number for the recommend on?

Last edited by sixtypilot57; 07-11-2019 at 12:05 AM. Reason: Forgot question
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Old 07-11-2019, 12:21 AM
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In order-
yes.
Holley owns Hooker. They are the same.
2002 pan might work. Holley 302-2 does for sure.
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Old 07-11-2019, 05:50 AM
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The sump length of the F-Body oil pan will prevent it from being installable with the Hooker Blackheart (AKA Holley)engine mounting brackets. The radius of its corners along the front end of the pan will also not provide the inner tie rod clearance that the Holley 302-2 and 302-3 pans do. The 302-3 is the best choice for use with the 64-67 A-Body application if you are using the Hooker Blackheart forward-bias engine mounting brackets as the chamfered front corners of its sump offer better clearance for the engine crossmember and the crossover brake line attached to it.
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Old 07-11-2019, 07:49 AM
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Thanks for the info. I may have to take my engine to a pro then, not sure if I’m smart enough to even install a new pan. Just curious if the f body pan would work if I went with different motor mounts.
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Old 07-11-2019, 08:33 AM
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Originally Posted by sixtypilot57 View Post
Thanks for the info. I may have to take my engine to a pro then, not sure if Iím smart enough to even install a new pan. Just curious if the f body pan would work if I went with different motor mounts.
Do yourself a favor, ditch the F-body pan and go with the Holley/Hooker forward bias mounts and the 302-3 pan. Having the engine slightly forward will greatly improve transmission fitment and offer the best driveline alignment. You will have a much better finished swap when you're done.

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Old 07-11-2019, 12:22 PM
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Default Mounts, oil pan, headers

Ditto what Andrew said-I have all Holley/Hooker in my 1970 GTO and have no issues fits like a glove.
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