1971 K10 6.2 Diesel Swap

[vdb11]

Hey all I haven't posted here in a while but I am getting back into researching. If you remember before I was considering a 472 caddy.

Now I am set on a 6.2 diesel. I know the engines well, and I already have a military 6.2 that just needs rebuilt.

The plan is to do this swap on a budget but I need some help! The plan is:

Stock NA 6.2
Keep the T350 (seems to shift fine, save $ for now)
I believe it has 3.73 gears, I am going to keep those.

Ok so here are my main concerns/questions. I have been doing a lot of reading and haven't found solid answers just yet.

1) (The big one!) WILL the 6.2 bolt fit with stock mounts? I have read BBC mounts can be used BUT my truck is 4wd, and IIRC, the engine is back 2 inches compared to a 2wd. I thought I read somewhere that some modification was required so the heads didn't hit the firewall. CAN ANYONE VERIFY/CLARIFY THIS?

2) Do I need a hydroboost? I have the vac setup now. If I do, where can I source one from? What is involved in the swap?

3) Anyone that has stuffed a 6.2/6.5 radiator in one of these trucks, how did you do it?

4) The T350 should work fine, but I read a diesel converter will be needed (from a t400?).

Any other tips? Does the exhaust clear the frame? Any helpful advice from anyone that has done this swap in a 4x4 would be greatly appreciated!

Vance

[67_C-30]

You will need BBC motor mounts. The manifolds hit the frame with SBC manifolds. I would think the heads might hit the firewall in the stock location on a 4x4, because they are close in a stock 2wd location. It will need the hydroboost. There is no vacuum signal from a diesel engine, and the vacuum pump that is on them will not produce enough vacuum for brakes. You will need the IP mounted vacuum switch to control vacuum to the modulator valve on the the TH350. If you have a CUCV engine, it won't be a problem, but if its a HMMWV engine, you'll need the switch. The radiator support would need a lot of modification to mount a 6.2 radiator. Most everybody uses the BBC 4 row radiator in these trucks, and they keep them cool.

I did the saw on my '67 C-30. You can check out my build thread below.

[special-K]

I've never done the swap,so 67_C-30's advise is great to follow. He is right that the 6.2 will be into the firewall. Heck,the 350 is mighty crammed back as far as that goes. I don't know what size rubber you want to run,but if it was me I'd seriously consider finding a 700r4. They are longer,but mostly adding O/D while you're into this would be a huge plus. My '85 Jimmy has 4.10s,35s,and is a 6.2/700r4 from factory. It's a great vehicle! The longer part is good because I have a friend who put one in a '72 K/10 with a 350. Rather than move the t-case cross member back,shorten the rear driveshaft,and lengthen the front he move the engine forward to the next set of holes...about 2.5"? I can get all the details. By doing this nothing else had to be touched and there's plenty of room between the engine and radiator. If you stay with your TH350 you will likely be moving the engine forward and doing the driveshaft work. On the exhaust...I have "heard" it mounts right up to the diesel manifolds. But,if you have to move things,I dunno. This was probably in 2wds.

[vdb11]

Thank you so much for the replies guys!
C-30, I actually did read through your build thread before haha it helped alot. I figured the diesel wouldn't make enough vacuum I just wanted to be sure. Hmm on the vacuum switch, I have it but not sure if it works haha. The engine did come out of a cucv. I just have to switch the top of the ip with a 12v version and I should be good.

So the BBC rad keeps your 6.2 cool? Also, with the BBC mounts, does it cause any trans clearance problems against the cab?

special-k, could you get me the rest of the details on that build? I would be very tempted to get a 700r4 if I didn't have to screw with moving the crossmembers and driveshafts. That was actually my original plan but I thought I would keep the t350 for the sake of saving money and that I wouldn't drive it much on the highway. Which is a tougher trans? I am not going to be doing any real heavy long hauling with it but it may have a heavy wagon of hay behind it every now and then. I wanted something that wouldn't rob the little power that I will have so I don't want too bad of a "slushbox". But I am gonna keep it auto for simplicity sake.

Does the 700r4 need vacuum like the t350? Sorry for all the questions I don't know too much about auto transmissions.

special-k, what do you get for mileage in your Jimmy? I have skinny but aggressive 33s on mine now and 3.73s.

[67_C-30]

The CUCV pump is actually already 12v. Only the starter and charging system on the CUCV 6.2's were 24v. It a hybrid system that allows all lights, interior switches and lights, wiper and blower motor remain regular 12v stuff, and they kept the IP 12v as well. The HMMWV pumps are 24v. I have no clearance issues with the BBC, because the 6.2 was basically designed to swap out with the 454's in trucks of the era it was built. A BBC radiator will keep it cool as long as you aren't cranking the fuel up too much (which kills economy anyway).

I can't speak for Tim's Blazer, but my M1009 Blazer with a 6.2 with a Banks Sidwinder turbo, TH400, and 3.08 gears gets an honest 20 mpg with mixed driving and a little better on the highway. It got slightly better when it was N/A, but the power night and day, and sounds so much sweeter now! -lol

84 M1009 CUCV Blazer 6.2 diesel Banks Sidewinder...

[vdb11]

Oh ok I didn't know the pump was 12V. That's good to know. I like the M1009! I have always wanted a M1008 but they are hard to come by and usually not cheap.

That's good to hear on the mileage. I am hoping to get 19-20 in town with the 3.73s. My laggy and lifted 92 gets right at 20 on the highway and its not even running quite right yet. I plan on keeping it NA, but who nows ha. I am used to driving around my hopped up 6.5 so it might be too gutless but we will see I guess.

Does the BBC rad require any core support modifications?

Also I like what you did with the exhaust outlet on your turbo. I did the same thing on my GM-3 a couple years back and it made a huge difference. Especially in sound. That thing whistled like no other! I have a big laggy HX52 on it now with a weedburner exhaust coming out right in front of the rear wheel. I love the way it sounds. Sounds like a loud semi driving around.

I am going to research the hydroboost swap so I can start to gather parts.

[special-K]

Yeah,I get 22 with the O/D and the final gearing with 35s/4.10s comes out to right about 3.73. I thought about putting the 6.5 turbo on it that I have,but to me this truck is about economy and with the N/A motors all the torque is right there right away from a dead stop. That 135hp feels like so much more in the bottom end. And,in the mid-upper end you are rolling along and it keeps it rolling just fine. Again,that torque keeps hills from pulling you down. I think 33s would be ideal with my set-up or 4.56s with the 35s. It does great,but I thing those combos would be optimum.

The friend I was talking about is a member here,but hasn't been coming here much at all (if any) lately. I think you should talk with him directly. I'll say something to him and we'll see about making that happen. He went through making the 700r4 work with the original NP205. I am a hardcore 205 fan,but in reality the 208 will do the job just fine. All the ones that are out there pretty well has proven that. If you could find a donor it would be best...cheapest.The later the better is all I know because they went through upgrades throughout their use in GMs. I feel they are a good transmission. My Jimmy runs strong with the one in it.