Step by Step 4L80e / 402BBC Swap

[mcmlxix]

I thought I would document my progress as I swap in a 4L80e and BBC into my 71 C/10 SWB Stepside....


I found a new in the crate 4L80e a few weeks ago.... GM p/n: 24211275
I can't seem to lacate this p/n on line. I think I'll call the local dealer tomorow and see what info they have... Supposed to be a HD version.


The 402 came with a TH400. The flex plate won't bolt up to the converter that came with the the 4L80e. Looking into my options...

The cooler lines vary depending on what year the transmission was designed and built. The newer ones have provisions for 3 coolant lines. They also have some snap ring type connection. Looks like the clips that hold our window crank handles on...


The newer ones have 7 bolt holes on the bell housing and the older ones have 6 holes.
I post more details as I get more details figured out.

There are a couple controllers available for the 4L80e and 4L60e. I am going wiht TCI because the price is almost half of thte Compushift one... Summit and Jegs sell them for about $650... But... You need to run a TPS. Throttle Position Sensor. They sell a remote moount version for $199.00. I bought a TPS off eBay for $20.00 and I'm going to attempt to make my own bracket...


My truck has a low hump cab. I have a removable high hump from the big block donor truck. I think there might be clearance issues but not sure yet. I am also replacing the cab bushings with new poly ones. The old ones are cracked and worn out... I want to be sure that a clearance issues isn't because of old worn out rubber bushings...

[69rut]

Thanks for the info. I have a 4.3 V-6 and 4l60e for the wifes '69. Some of the harness is missing and I have no computer, but for $400 who would complain?

[2500HD]

mcmlxix

any progress?

[mnunn454]

Super cool.

You're going to love that BBC power plus the overdrive.

That combo should be nearly bullet proof.

Glad to see you forging the way with the 4L80E swap in. Makes it easier for me when/if I round that corner.

Thanks for posting the progress and pics.

[mcmlxix]

Sorry all... we bought a new house and moving next week... its stalled my progress for lack of funds and time.... (now I have even less time and less money then the usual poverty that I have been burdened with...LOL)

I did find out that the original flex plate will bolt up using 3 of the 6 holes. There are two bolt patterns. One pattern has a slightly larger diameter will fit the stock 4l80e converter that come with the trans...

I was told you can convert the cooler lines to AN or something similar. I will probably go with the JEGS Push-Loc Hose. Seems like a nice inexpensive alternative to braided line.

[GREASEMONKEY72]

sweet truck and cant wait to see the swap when its done

[Morgsie]

Originally Posted by mcmlxix

Sorry all... we bought a new house and moving next week... its stalled my progress for lack of funds and time.... (now I have even less time and less money then the usual poverty that I have been burdened with...LOL)

I did find out that the original flex plate will bolt up using 3 of the 6 holes. There are two bolt patterns. One pattern has a slightly larger diameter will fit the stock 4l80e converter that come with the trans...

I was told you can convert the cooler lines to AN or something similar. I will probably go with the JEGS Push-Loc Hose. Seems like a nice inexpensive alternative to braided line.

The 4L80E was put behind a 454 in the early 90s GM trucks. I'm sure you could order a flexplate form GM. I worked on a 95 3/4 GMC, that had a 350/4L80E, I wonder if the flexplate is the same on a SBC as a BBC? Just a question/suggestion: why not go TBI? I bet even with a custom chip made, it'd be cheaper than a $650 controller kit and effing around with installing a TPS. My 2 cents.