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Thread: 4.3 to 5.7L swap

  1. #1
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    4.3 to 5.7L swap

    Hi people! This is my 1st post here and my introduction.
    I am currently swapping out my son's 1995 C1500 WT 4.3L and 4L60E trans with a 1994 C1500 5.7L and same trans. The 4.3 has 320K and is still running alright, just lack of power. The trans started slipping so a change has to be made.
    I already pulled the 4.3 and trans.

    The 5.7 is on the engine stand and we are almost ready to put her back in.

    The 4.3 motor mount is extended and broken, and it looks like I have to remove the shock/coil spring and lower control arm to get to the nuts on the motor mount tonight.

    I have the computer from the 5.7, and I want to know is do you foresee any other problems we might encounter.???

    The truck is worth it, BTW!

    Thanks,
    Gary

  2. #2
    Senior Member batty1214's Avatar
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    You should have a fairly straight forward swap there....... and I think you have what you need... you are changing out motor mounts, and not using the old ones right?

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    Yep, brand new ones. The 1 thing that I overlooked was the mount nuts located inside of the framerails. The 4.3L adapter plates are made of thinner gauge sheetmetal and pretty flimsy. 1 ear was broken off 3/4 of the way, and I had to jam the nut with a big wrench while my son used the impact to spin the bolt. It came out, easily enough though.

    I've had the truck since 2002, and I gave it to my son when he was in HS so that he could go to work. He got the money to get the truck repainted, we rebuilt the entire suspension and steering. New close ratio steering gearbox, 3" lift coils in the front, Lift coil over shocks in the rear. New grill and front end, lights, fiberglass cowl hood with working lift pins etc. Line-Ex bedliner and an aluminum diamond plate tool box. I'll attach a picture when I get the chance.

    I made a deal with him that if he buys the parts, I'd do the labor and teach him along the way. 1 issue is the 17" rims, threw off the speedometer by 8mph and he got his 1st speeding ticket

    How do I fix that issue? I know that with the Turbo 350's we would swap out the speedo gears, but this 4L60E is electronically controlled and how can I locate the black box and fix it?

    The trans is the 3rd one to 'malfunction' on me, it was rebuilt by a local trans shop 2 years ago and it started slipping 4500 rpms @ 60mph. I'm sure that the 1994 trans is going to develop a problem as well. I'm not a big fan of them at the moment .

    The truck is a daily driver, and his pride and joy. 2 nights ago I replaced the starter, power steering gearbox and alternator, waterpump and the A/C is 2 months old.

    I got a trans filter,gasket & fluid to replace next along with a new trans mount. The 4.3 and 5.7 Y pipes are identical, and I am replacing the O2 sensor and donuts. The guy I bought the 5.7 from broke off 3 studs in the exhaust manifold I fixed 1, 2 more to remove tonight.

    I plan on getting the motor and trans back in this weekend.

    More to follow.

  4. #4
    Senior Member batty1214's Avatar
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    well, the 4.3 trans(if it wasn't slipping) would have bolted behing the 5.7..... the 4.3 is a 5.7 that had two of the cylinders fall off...... Im looking at swapping a 5.7 into my 93 s10..... so let me know how it goes.

  5. #5
    Senior Member bubbatrucklover's Avatar
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    [quote=garybt3;112985]

    I made a deal with him that if he buys the parts, I'd do the labor and teach him along the way. 1 issue is the 17" rims, threw off the speedometer by 8mph and he got his 1st speeding ticket

    How do I fix that issue? I know that with the Turbo 350's we would swap out the speedo gears, but this 4L60E is electronically controlled and how can I locate the black box and fix it?



    quote]

    Sounds like your kid has a cool dad!HOPE he appreciates it!

    As far as the speedo prob. a while back I had contacted a shop used by FHP that would GAURANTEE calibration! Of course if you don't live by Jax, the drive PROBABLY isn't woth it!
    Siggy by Crimson Dragon >>>>>>>>>>>>>>>

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  6. #6
    Senior Member silverhairdeere's Avatar
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    about half way down the page on this link should help . it's called a ERA , goes for $ 169.00
    Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

    shd

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    Quote Originally Posted by silverhairdeere View Post
    about half way down the page on this link should help . it's called a ERA , goes for $ 169.00
    Speedometer Gear, Speedometer Gears, Ford, GM, Dodge 700R4

    shd
    Great page, thanks!

    I got a lot of engine clean up work done today, and replaced the trans filter and gasket. Sunday I have to remove the coils springs to replace the 4.3 motor mounts with the 5.7 frame mounts...I'm not looking forward to it very much
    I rebuilt the suspension 2 years ago so I should not have too many problems getting it done. I still need to remove 2 broken studs on the exhaust manifolds once the motor mounts are in.
    The fun never stops

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    Had a couple of 'surprises' pop up over the weekend.
    Did you know that the 4L60E transmission is slightly different from 1994 to 1995?
    Me either, apparently theres a short shaft version on the 94, and a long shaft version on the 95 (the part that the Reverse Neutral Safety switch utilizes) so I need to re-open up the trans to figure out if I can swap the 2 of them out.
    While swapping out the motor mounts, I learned a few other things;
    Yes you can drop the shock out, compress the coil spring and use a floor jack to remove the lower bolts on the lower A arm inorder to gain access to the back of the nuts on the motor mounts. They are not welded in, and they spin freely, and you have to hold them to remove the adapter plate used for the 4.3 V6. You pretty much need 2 people to do this job, and the motor mount swap takes roughly 10 minutes to do each side.

    However, getting everything to line back up is the real trick.

    I went ahead and popped off the lower ball joint, tore the rubber boot, and then *** remembered *** that they need to be pressed out and the new one pressed in. Like many people, I don't have a press @ home. ****. And I did it on a Sunday, and no shops are open around here, so I'll visit one this week and get that done.

    If anyone know a good trick for 'holding' the coil spring in place to the upper mount, while you re-install the lower A arm, 'I'm all ears"

    I am also going to take the extra down time to change out the oil pan gasket and get a peek inside of the motor and look for any problems.

    I want to positively verify that it is indeed a 4 bolt main motor & make sure that the oil pickup screen is not clogged if it is, I'll install a new pump.

    Other than those issues, it's been a fairly straightforward deal.

    The broken 4.3L motor mounts may explain why the transmissions have been been puking every 2 years.

    If I had the money, I'd get a new one from B&M or maybe Certified Transmission and be done with it I make myself laugh sometimes...


    Thanks for the help, guys, are there anymore great websites that I can check out this week?

  9. #9
    Senior Member bubbatrucklover's Avatar
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    Quote Originally Posted by garybt3 View Post

    Other than those issues, it's been a fairly straightforward deal.

    The broken 4.3L motor mounts may explain why the transmissions have been been puking every 2 years.

    If I had the money, I'd get a new one from B&M or maybe Certified Transmission and be done with it I make myself laugh sometimes...


    Thanks for the help, guys, are there anymore great websites that I can check out this week?
    I don't know if that was meant as a joke or not.

    Seems like anytime I go to wrench on something there are "hidden suprises". You just named some PITA things I could see hapening and have hapened to me like "no one open on a Sunday"
    Siggy by Crimson Dragon >>>>>>>>>>>>>>>

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    Quote Originally Posted by bubbatrucklover View Post
    I don't know if that was meant as a joke or not.

    Seems like anytime I go to wrench on something there are "hidden suprises". You just named some PITA things I could see hapening and have hapened to me like "no one open on a Sunday"
    If I could afford a new trans I would go that route, but I can't so I have decided to take another look at switching out parts myself, and after re-opening the 94 4L60E and getting a good look, i decided to take both trannys to a local expert and get an estimate.

    I was watching extreme 4X4 this morning and he was rebuilding a 700R tranny and I got a good tip. it seems that there are HD versions of the 4L60E and 700R transmission out there that can be Identified by having the letter 'K' on the housing. My 95 has that K and at least that's a good starting point.

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