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Advice on engine swap.

1

1985 K10 Warhawk

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TLDR: 99 L29 454 swapping into 1985 k20 sub (700R4 tranny). What should I do/replace while engine is out? Any advice/wisdom? I intend to mate to the existing 700r4...where do I even start!

The engine on the old girl finally tuckered out. She has an awful rod knock now..a knock the developed the same evening I purchased a new challenger srt 392. Any how, after the initial shock of buying a new car faded from my bank account, I was able to convince the wife to buy a new donor vehicle: 1999 C2500 Suburban w/ 7.4L 454 sporting 167k miles. I almost feel bad ripping into her! (I have been planning for the 6.0L LQ4 or 6.2LQ9 and have done a fair bit of research on that swap...But this one fell into my lap for stupid cheap (Currently 3k under budget!).. pretty sure I am going to make money on this swap after i part out the tranny/body/old engine/tires)

The first owner kept meticulous records, with every oil change / maintenance from 12/1/98 -> 7/1/2014 putting on a little less then 130k in Tuscon Arizona. I don't know much about the history since then, other then the owners word saying he took care of it and I have a new tires receipt from 10k miles ago.


The prize.




With graphics strait out of Miami Vice!

Valve cover leak

I bought vehicle, drove it to a bar, had a few drinks and then it wouldn't start. The parts store closed 10 min prior to me walking out. I had to leave her 70 miles from home. I return to her a week later..After buying a new starter and replacing it, I discovered how corroded battery cables can make a starter engage, but not spin (Scratched our heads for a good hour figuring this one out.) She takes a second to build up fuel pressure, so likely need to replace the fuel pressure regulator. She smells of gasoline, but i couldn't identify any leaks.

She idles fine, pulls fine, and drove the 70 miles home with out any awkward noises.

And that is kind of where I'm at... I haven't done much research on this particular swap. Anyone familiar with this engine or this swap that could point me to some resources or even just a laundry list of things to look out for / fix. I don't want to attempt an engine rebuild at this time.

I had planned to replace the fuel pressure regulator and water pump and valve cover gaskets (Oil pan if it leaks, but I hadnt seen any leaks yet).

I don't really know what I am doing, but just like the axle swap.. here I am.. doing it!


Unrelated note.. the damn thing has the same hubcaps my last 1980 donor 2500 sub had! Way to recycle the parts bin GM.. for 19 years!
 
The swap is relatively straightforward and there's a lot of knowledge out there.

The engine will mount up just fine, and dropping in a Vortec EFI pump to feed the engine isn't a major ordeal. The main thing is upgrading your fuel system to handle high pressure injection.

One area where you'll have to make a decision is the transmission. The 700R4 will require some fabrication to make the TV cable work with the Vortec intake setup (unless you ditch EFI and go carb or convert to TBI), and unless it's built it's probably not going to have a long life behind a big block. I'm assuming that the donor burb comes with a 4L80E. It would be my choice to just use the transmission that came with the big block. It's a larger transmission, so making it fit may mean some crossmember/driveshaft work and an adaptor to hook up the NP208, but in the long run I think it would pay off.

As far as general swap advice, make sure you devote some time to a good bay cleaning. Replace the motor mounts. It's easier with the engine out and they're probably old and not ready for big block torque. I'd at least inspect rear main and oil pan seals, as if needed they are easier to service with the engine out. If it's in the budget, replace the crank/cam sensors that can fail over time and cause issues.
 
I replaced the timing chain & gears and the oil pump & screen if they looked bad before installing a engine I'd bought to swap in--much easier to do it when its not in the chassis..
Only one of several engines had a timing chain & gears that were not sloppy and the cam gear was the nylon coated ones,all the teeth were stuck in the oil pump screen and the bottom of the oil pan..
I also replaced all the freeze plugs--nothing sucks more than having one behind the flywheel start leaking after you just got the "new" engine in..(the others are no joy to get at with the engine installed either!)..
 
Correct. The donor vehicle is 2wd.

I just started looking into upgrading the 700r4 internals (She lunges when put into gear and has a slow drip right now anyhow) and understand i will need to put a bit of money into it to live behind a BBC. I own a pressure washer and had intended to clean the bay up real good! Thanks for the tips thus far.

I leave on vacation for a week and am hoping to start the weekend of July 22nd.. Need to start ordering parts now!
 
replace intake and valve cover gaskets check distributor gear fuel pump will fit in tank for older burb and plumb up fine did it with a 96 bb. Are you going to run the engine harness and computer? What i did on mine was ll wiring from headlights to tail because of all the grounds the vortec needs. you can swap out the tailshaft on the 4l80 to a 4x4 one with a tone ring on it then put a 32 spline 241 behind it and be done. the 4l80s have 2 speed sensors on it if they dont match up the tranny will go in limp mode got more info just not enough time tonight
 
I would recommend you get a 4x4 4L80e to put behind that big block. It would likely cost less than building your 700r4 to last behind a 7.4L long term. If you do decide to run the 700r4, then you'll need to make sure you get the engine controller re-programmed with a manual transmission tune to eliminate any codes / limp mode / other issues that will crop up with the transmission "missing".

Wiring should be pretty straight forward. You'll just have your basic battery power / ignition power / ground, check engine light, OBDII port, speedo output, tach output, fuel pump relay, brake input, cruise control wiring etc. Nothing too exotic to do there. A simple bussman stand alone fuse block installed under-hood would work nicely. All the major connections you need are in the bulkhead connector already and would just require you to identify and connect the wires together.
 
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