1966 LS swap info

[statenine]

Hey all, I am looking to put a 5.3 LS in my '66 SWB, but not sure which tranny yet. Either the 4L60E or 6L80E (the latter is the same as my 2011 GMC Sierra). With either of these transmissions, will there be any clearance issues with a standard hump transmission tunnel on my '66 cab? I know when using the Porterbuilt dropmember kits, they raise the motor/tranny up so a high hump tunnel is required. However I will be using the stock crossmember with an LS motor mount kit, so not sure if that raises the motor/tranny any? Hopefully I won't need to install a high hump tunnel in order to do the swap.

Also, my truck is on airbags so it sits pretty low when aired out. With an LS in there, will the oil pan be the lowest part of the front end? Currently the lower control arms are the lowest point on my truck in the front. They touch the ground when aired out all the way. I am hoping that with an LS swap the LCA's will still be the lowest point.

Thanks in advance!

[racecougar]

The 4L60E will clear without issue.

If you're running a stock LS truck oil pan, it will sit ~1" lower than the engine crossmember...depending on which mounts you run.

[Mathew21]

In my 66' I used 4L60E with standard hump tranny tunnel with no clearance issues. I used a f body ls oil pan.

[statenine]

thanks for the confirmation guys! Does anyone know if the 6L80E will clear?

[Clyde65]

Without changing the oil pan from stock to a "hot rod pan" your oil pan will be the lowest, sticks out about 1-1.5" lower

[zach_carver]

4L80e and 6l80e will both require tunnel modifications. Ive not seen many trucks our body style with 6L80s though. I know 4l80e require tunnel hump modifications

[statenine]

ok thanks Zach. I will likely go with the 4L60E anyways but just getting as much info as I can.

[Clyde65]

The pcm must come from a truck with a 6l80 trans, I don't think the 6l80's are as big as the 4l80 though. Anybody know how big the 4l80 is? I'll take some measurements of the 6l80 Saturday.

[Captainfab]

I have not made an exact comparison but a 4L80E should not be any 'bigger' than a TH400 as far as tunnel clearance is concerned. The 4L80E is just longer. I installed a TH400 in my '66 Suburban with a low trans hump. But I did move the engine and trans froward 2".

[statenine]

thanks all! do I also need a special gas pedal to work with an LS motor? Or can you retrofit a stock pedal to work? can you also use the stock gauges (speedo, temp etc.) or do you have to upgrade to electronic gauges?

[Clyde65]

A 67-72 pedal assy works very well and is reasonable too.


Gauges will need to be updated to electronic. Check out the LSx section here and the FAQ's for specifics.

[racecougar]

Originally Posted by statenine

thanks all! do I also need a special gas pedal to work with an LS motor? Or can you retrofit a stock pedal to work? can you also use the stock gauges (speedo, temp etc.) or do you have to upgrade to electronic gauges?

Are you running a DBC or DBW arrangement?

I know the DBW can definitely be adapted to work with the stock pedal...with a little ingenuity.

[AustinBelair]

Originally Posted by zach_carver

4L80e and 6l80e will both require tunnel modifications. Ive not seen many trucks our body style with 6L80s though. I know 4l80e require tunnel hump modifications

Negative. I have a 4L80E in one of my 66 trucks and did not mod the tunnel. It's a low hump/

[rvrfoot]

It matters on how your motor is mounted to.

[statenine]

I was told by someone else that You can run the stock gas pedal if you use a cable style throttle body rather than the fly by wire type. Is that true?

[Clyde65]

Originally Posted by statenine

I was told by someone else that You can run the stock gas pedal if you use a cable style throttle body rather than the fly by wire type. Is that true?

Unfortunately no, our trucks have linkage type accelerator and not cable like the DBC LSx throttle body.

[statenine]

Gotcha, thanks Clyde!

[statenine]

is it possible to use my stock gas tank?

[jweb]

You should be able to use your stock gauges, I do in my ‘51.
Dakota digital makes an adapter for the speedo
http://www.dakotadigital.com/index.c...rod/prd886.htm

I also use the stock temp gauge and oil pressure, it works great and I will do the same in my ‘64 Suburban if I can ever get to working on it.

[statenine]

I was told I can use my stock tank if I have a return line running to it. What is the best way to add a return line to the stock tank?

[Captainfab]

You will want to use your current supply line for your return line. then add your new larger supply line thru the sending unit flange. I know there are a couple builds on here with either a LS or earlier EFI conversion that have done this.

[statenine]

Thanks Captain I will search around for those build threads!

[Soyuz008]

As stated, the placement of the engine determines the tunnel clearance, ground clearance and driveshaft U-joint angles.

Here is a 6L80E in my '62. It does not clear the low trans hump. For reference, the angle iron is approximately 4 1/2" inches above the floor.

The second picture shows the GM "Hummer" oil pan is still higher than the front cross member.

This engine position is with a 1979 front cross member, stock 79 motor mounts and home made trans mounting bracket.

[statenine]

Thanks Soyuz. As everyone is stating, where the motor is mounted will determine clearance. I am looking for a bolt on motor mount for LS swaps. I know there are a bunch of different ones. Does anyone know of a bolt on set that sets the motor to where it will clear with the 4l80e? What motor mounts are typically recommended with my application?

thanks guys for all the info, this is all new to me!

[Captainfab]

Here is one of those threads I was thinking about.

http://www.67-72chevytrucks.com/vboa...=641267&page=4

Do you realize that there is a LS swap section of this forum that likely has all the info you are looking for?

Originally Posted by Captainfab

You will want to use your current supply line for your return line. then add your new larger supply line thru the sending unit flange. I know there are a couple builds on here with either a LS or earlier EFI conversion that have done this.

Originally Posted by statenine

Thanks Captain I will search around for those build threads!