K20 Swap questions

[WS7z]

I am working through the idea of a 6.0 swap into my K20 now that the transmission died on me. I have sourced a 4l80 out of a 2003. The NP205 has been rebuilt and now has a twin stick setup. I tracked down the transmission adapter from a 400 and had it machined to mate up to the 4l80. Now its time to jump into the engine.

I have a few questions that I have not been able to get good answers on with my own research. Any help is much appreciated.


1) What is the difference, if any, between how the engine mounts on 4x4 vs 2x4?

2) Can i just use adapter plates for the LS to mount to my existing motor mounts?

3) With the long 4l80 i would ideally like to get the engine far enough forward to keep driveline angle manageable. What is a good option for mounting the engine as far forward as possible?

4) how far forward can the engine go before it become a problem with vehicle drive-ability or fitting in the available space?

5) will i have clearance problems with the stock hood using a 6.0 and a stock mounting location?

6) Is there a specific oil pan I need for the 4x4 chassis?

EDIT:

7) any links to 4x4 builds would be much appreciated!

[BR3W CITY]

1. Not sure, but pretty sure its the same as the 2wd trucks at least in terms of the physical motor mounts and mounting location.

2. Yes. Worth saying that lots of guys like the full-replacement mounts like dirtydingo because they offer some adjustability as well. The regular swap plates are totally functional tho. If you need a crazy engine position, an option would be to make (or have made) a set of adapter plates with the LS holes moved forward.

3. I kinda answered in 2. You shouldn't need to put the motor crazy far forward, there have been plenty of 4x4 swaps so its worth checking their build threads for suggestions.

4. With the radiator and an electric fan, you have a good amount of space, probably up to 2-3" before you'd really be cramped for the fitment of the front accessories and intake. Some of the guys running the larger radiators or those running a mechanical fan have closer to 3/4-1" of extra space.

5. The engine sits pretty low in the bay, so the hood should fit fine.

6. At least in the 2wd trucks, the stock pan hangs anywhere from .25-1.00 past the stock crossmember. I believe it should be the same on the 4x4 but I'd wait for someone else to verify. The mount choice will affect the engine height a little.

[Jstock85]

I dropped a 4.8 in an 85 c10 yesterday. Although I realize our set ups are somewhat different Brew city is accurate on all fronts! I will through out one small piece of advice I went with those ICT billet adapter plates on amazon for $35 trying to save a few dollars and had a lot of trouble. Not all of the holes are usable because of the contour of the engine block. I got a set of Dirty Dingo slider mounts for 73-87 chevy trucks (PN 2500c I think) and they fit like a glove. I did a total rebuild myself (except for cam bearings) and those slider mounts were by far the easiest to use and best value on the whole project!

[Jstock85]

Paid $104 for the DD mounts I believe.

[WS7z]

Thanks for the info. I have been looking at Dirty Dingo. They have a full crossmember replacement option. If their sliders accomplish the same objective that would be a great option.

[SlowGreen71]

There's plenty of room to place it wherever you want. I built my crossmember and half of my motor mount (other half off amazon) so I could place it how I wanted. I ended up a little more forward and up a tad so I would be able to retain the stock ls a/c pump. Would try place the t-case crossmember in the factory spot and see where that lands your engine. The biggest concern of placement will probably be clearance between the pan and front differential if you're not lifted.

[cdub2010]

1977 k20 I used DD sliders with stock clamshell mounts on my 5.3 with 4l80e and 241C. I had to trim the stock cross member on drivers side for oil pan clearance. The truck pan is pretty close to the front diff. Im using stock springs with adding ORD front shackles for a little bit of clearance. I didn't have to modify either driveshaft with the current placement. I think this picture shows the end placement of the engine. Plenty room for stock 2005HD intake, fan and radiator with shroud. Using all gm parts will make it easier to fix in my mind. Ill try to update with a picture of everything in place

[suburban99]

You don't mention what year your K20 is..On my 72 K10 6.0 swap I used the DD cross member and the DD sliders. My 6.0 is bolted to a TH350-205 in the stock position. It is VERY close to the firewall. Lots of room up front with mechanical fan and stock Rad and shroud. I built a 700R4 for it recently and will install it at some point by moving the engine forward about 1.5-2.0" The DD cross member is a quality piece. I nave about 15000 miles on my conversion, Highly recommended.

[TCCGRIZ]

Originally Posted by suburban99

You don't mention what year your K20 is..On my 72 K10 6.0 swap I used the DD cross member and the DD sliders. My 6.0 is bolted to a TH350-205 in the stock position. It is VERY close to the firewall. Lots of room up front with mechanical fan and stock Rad and shroud. I built a 700R4 for it recently and will install it at some point by moving the engine forward about 1.5-2.0" The DD cross member is a quality piece. I nave about 15000 miles on my conversion, Highly recommended.

Did you have to change the flex plate to match up to the th350?

[WS7z]

Originally Posted by suburban99

You don't mention what year your K20 is..On my 72 K10 6.0 swap I used the DD cross member and the DD sliders. My 6.0 is bolted to a TH350-205 in the stock position. It is VERY close to the firewall. Lots of room up front with mechanical fan and stock Rad and shroud. I built a 700R4 for it recently and will install it at some point by moving the engine forward about 1.5-2.0" The DD cross member is a quality piece. I nave about 15000 miles on my conversion, Highly recommended.

The chassis year is '67. Cab and title are a '70. That DD cross member looks like a good option. Turns out the 67-72 chassis is a tough nut to crack for an LS swap unless you highly modify or replace the cross member.

What is everyone finding out is the best option for oil pan clearances? Is there a specific pan I should look for or does any pan fit?

[Jstock85]

I put a 4.8 to a 350 and used the flex plate from the 4.8 and the self centering ring. It fit fine with No spacer needed.

[WS7z]

Been over a year working on this on and off. Progress update:


Engine:
Old engine came out in August '19. Need to find time to put it up for sale. Until then she sits in the corner with the rest of the stuff not needed for the build.





Going with an LQ4 for the swap. Engine has just over 200k miles on it. I went through and put in new seals on the block. The bearings looked good enough that I dont see a need to do a full rebuild at this time. Decreased the engine and intake. New knock sensors installed as well. Its mostly put back together and sitting on the engine stand. Drive by wire system will be used.




Mounts:
After a good 6 months of searching it became very clear that 67-72 4x4 chassis requires a different cross member to fit the LS engine. Sliders alone are not going to cut it. I could only find two fabricators offering options. I looked hard at Dirty Dingo and Pacific Fabrication crossmember kits. Decided to go with Pacific Fabrications cross member about 2 months back. I'm so-so on the kit. Some of the holes didnt line up. A little encouragement solved the problem.



Quick test fit today to verify i clear the fuel and brake lines. So far so good.


Oil Pan:
Some installers seem to report problems with clearance on standard truck oil pans with 4x4 installs. PF confirmed i should test fit to verify. Looks good so far.
Decided to verify the fit before putting everything into the truck. Crossmember cleared fine so I will be using stock oil pan.

Goals before Christmas:
- Install Crossmember
- Test fit engine into truck
- Identify options for gas lines & fuel pump
- Buy new radiator & fans then install.
- Begin locating wiring harness inside the cab

Long term list:
- Coil packs relocated off the valve covers
- Figure out how to get the 4l80e into first gear using the stock column shift hardware.
- Verify fit of 4l80 to NP205 transfer case (this one will be its own post later)
- Locate new transfer case bracket after engine is in
- new drive shafts
- new exhaust
- engine tune
- etc, etc, etc

[WS7z]

Got the engine test fit. Looking good so far. Seem to be having problems with the clearance between the exhaust manifolds and the frames. Wondering if anyone else has seen this with the LQ4 engines in these K20 trucks?

[WS7z]

This image shows how tight the exhaust manifolds are.

[pilotXC]

Originally Posted by WS7z

This image shows how tight the exhaust manifolds are.

I'm doing an LQ4 in my K20 as well and through some reading and youtube time, the manifolds do not fit between the frame rails with much, if any clearance. Especially the passenger side. I don't know which headers do fit, but believe there is at least 1 or 2 companies that makes ones that clear. I went with DD cross member and mounts. Not sure I love it either, had to relocate brake lines, which I wasn't expecting to have to do. Fuel line has to be relocated anyway, so just pulled that out all together.

[pilotXC]

Originally Posted by WS7z

I am working through the idea of a 6.0 swap into my K20 now that the transmission died on me. I have sourced a 4l80 out of a 2003. The NP205 has been rebuilt and now has a twin stick setup. I tracked down the transmission adapter from a 400 and had it machined to mate up to the 4l80. Now its time to jump into the engine.

I have a few questions that I have not been able to get good answers on with my own research. Any help is much appreciated.


1) What is the difference, if any, between how the engine mounts on 4x4 vs 2x4?
Biggest difference I know of is the cross member. Also, you need to figure out the transfer case. A 205 will not bolt directly to the 4L80 without a modified TH400 adapter plate (sounds like you got that part covered) and a swapped out female input shaft. Offroad Design has them both. Can also do the advance adapter version, but you need a 2wd transmission output shaft and a reluctor ring added on the rear VSS of the transmission. An NP208 or NP241 bolt directly to the 4L80 and for on year they made an NP241 with passenger side drop that has the VSS in it, 1991. You also need to think about the 2 speed sensors. In a 4wd the rear one is in the transfer case, in 2wd both are in transmission. You can modify your 205 rear housing to use VSS but you have to have digital gauges to do that. Better option is the dakota digial pulse sensor, just make sure you tell whoever does your harness what you are planning before they do it. You'll need to have the wiring harness modified or buy a new one as well that will work with your truck.

2) Can i just use adapter plates for the LS to mount to my existing motor mounts?
I don't know on this, but seems like just about everyone uses the 73-87 "clam shell" mounts. They are an option with the Dirty Dingo cross member kit and probably make the whole thing a bit easier?

3) With the long 4l80 i would ideally like to get the engine far enough forward to keep driveline angle manageable. What is a good option for mounting the engine as far forward as possible?
The dirty dingo mounts with the clam shell have about 3-4 inches of adjustablity in them. Not sure how much it works as I've not got my engine in yet. If you switch your transfer case to something with a slip yoke, you'll need to modify your driveshaft either way. Otherwise, you'll have to modify a 208 or 241 transfer case output to be a u joint instead of slip yoke.

4) how far forward can the engine go before it become a problem with vehicle drive-ability or fitting in the available space?
Not sure, but seems from research you have a lot of clearance, especially if you choose to go with an electric fan set up.

5) will i have clearance problems with the stock hood using a 6.0 and a stock mounting location?
Pretty sure this is no problem at all.

6) Is there a specific oil pan I need for the 4x4 chassis?
I think the stock pan will be fine, but there are a lot of options if you want something else.

EDIT:

7) any links to 4x4 builds would be much appreciated!

Mine is hardly a build, just an engine swap, but am working on trying to document the process. I'm about to test fit the engine and see how the transmission cross member fits in the next day or two and will try to keep it updated as I go.