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A few weeks ago we finally put the finishing touches on Project Yukon’s late-model engine swap — a task not nearly as difficult as most sales people will claim, but still not for the faint-of-heart.  The good news: The Yukon’s running great with its new heart, and it’s a lot more driveable than it was before the swap. 

Read on past the jump for some pictures, sounds, and a final project summary.

After we installed the new Chevy Performance Parts H.O. 350 in our last post, the Yukon was running, but not well.  Though we had no major problems, we did have a number of minor problems that added up to some severely annoying crap.

First of all, we had forgotten to move over the knock sensor from the old engine.  It’s way down there on the bottom, and even though we saw it there, we just forgot when it came time to pull and install it.  This was causing the ECU to do all sorts of crazy stuff to try and reconcile the lack of knock sensor input, causing the timing to go crazy and the engine to utilize a screwball fuel mapping.  Removing and installing the old sensor fixed the problem.


The lesson to be learned: Make a checklist as you’re tearing down the other motor.  A number of other small problems like this caught us out — things we knew about at the time, but forgot about when it came time to remedy them weeks later.  Use your checklist on the reinstall, and you’re good to go.


We had a couple of coolant leaks, most of which cleared up very easily.  But one didn’t — a leak from the line running to the heater core.  It connects to the manifold with a somewhat complex connector that we’d managed to mangle a little bit.  A switch to a good ‘ole standard (and well-sealed) connector did the job just fine.


It’s worth noting that some 350s — like ours — utilize a really annoying combination rubber-and-silicon intake manifold seal that’s a bitch to install.  We had to try ours twice, but on the second install it worked fine.  Don’t go light on the goop — you’ll end up doing it again.

We also had the timing screwed up a little bit as we forgot to remove the plug to disable the computerized timing adjustment when we were setting static timing.  It really wouldn’t have mattered much because the missing knock sensor was driving the computer nuts anyway, but afterward it made a difference.  It’s an easy process of removing a wire from the computer, then setting timing like with any other V8.

With leaks stopped, the computer happy, and timing set to stock, it ran quite decently, though we’d also forgotten that the Yukon had been sitting a while before we brought it into the shop.  While the gas didn’t smell, it had broken down enough to cause low-octane problems.  A full tank of 93 later, and it’s running great.

Read on to page 2 for our end-of-project advice and more photos.

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11 Responses to Project Garage: Yukon Engine Swap (Part 5) — Complete!

  1. ambush27 says:

    what did you do for the transmission on this project?

  2. Lorenzo says:

    Having heard the vehicle first hand, I can say that it is very, very impressive!

    Good job!

  3. Erick says:

    how did the engine run before the computer upgrade? Would this be legal in california?

  4. Chuck Cage says:

    ambush27: This was an engine swap, not a drivetrain swap. After discussions with GM engineers, we believe that the stock transmission (a 4L60E) and 4WD driveline can handle the new power. We are, however, currently installing an aftermarket transmission controller which’ll allow us to move the shift points — and install paddle shifters.

    Lorenzo: Thanks!

    Erick: It idled ok before the computer upgrade, but didn’t like to receive any strong throttle inputs. The new fuel map improved things significantly. We’re in Texas, so we’re not intimately familiar with CA legislation. The H.O. 350 isn’t CARB certified, so if they discovered the different engine, you’d be in trouble. That said, the headers we picked are 50-state legal and would be fine in CA. Also, according to all the documentation we have, this engine — when coupled with the stock catalytic converter as in our application — should pass the sniffer test easily. So, it does beg the question how they’d actually *know* that it’s a motor with different internals. The block (other than sporting new paint) isn’t that different, and certainly isn’t different to the untrained eye. Of course, you should do your own research for your specific area before launching into a project like this.

  5. Erick says:

    does your sniffer test check for nox in texes by using a dyno??

  6. ambush27 says:

    its good that the stock drivetrain is good enough for your engine although I’d think that it couldn’t hurt to install a higher end torque converter and a transmission oil cooler.

  7. Erick says:

    are you still using the stock egr valve??

  8. Billy Suddeth says:

    O Joy, my bad though, you did fnish the project and kept this thread alive. I am anxous to go read 3-4-and 5. Good job you guys. I don’t know you, vice-versa- but I am proud of you. Digital camers are useful in projects, like I photographed the electrical circuts in my wood shop walls before the were covered up. Now I’m ramblng, again thanks for sharing your story. Bill

  9. Neil says:

    Awesome project! I’ve been following this thread for some time…anxiously waiting for an update. So, after a year of driving/testing, how has the yukon held up?

  10. Scott says:

    If gas was cheap, I would be very impressed with what you have done. How about substituting an Isuzu 4 or 6 cylinder Turbo/Diesel in a similar vehicle and showing us the problems encountered, in addition to the advantages and disadvantages, of putting a GOOD Oil burner in a modern vehicle, like a Tahoe or Silverado?

  11. Brian U says:

    I own this vehicle now and I’d like to find out more on the spec of the engine and transmission setup. I like the ride, but I need to make a few tweaks and want to do it right the first time. Tkx

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