LS Swap: Introduction, newbie, planning...

[Davidf]

Originally Posted by TrybalRage

I'm not sure on a 71. You'd have to look up the resistance ratings for the sensor and what your year truck would use. From what I understand thought, GM was pretty consistent with things like that for many years.

Yes, GM eventually got consistent, but I believe it happened well after 71.

[Davidf]

Yep, left head is cracked...baby poo on underside of valve cover. Right side is just oil and 185k mile crude. I think I will replace both heads with stock 862 or 709's. And, since the lifters ticked a few seconds on cold start, I will replace all lifters while the heads are off. At least the knock sensors and water pump are new(ish).

Going to stop short of a full rebuild...unless

And, man was that engine dirty!

[ls1nova71]

Does the engine have 706 heads? If so, could be a set of Castech heads that were known for cracking.

Also, the '98 coolant temp sensor may move the gauge in a '72, but won't be accurate. Tried that 20 years ago on my '71 Nova, which I'm sure uses the same internal gauge parts and it didn't work.

[Davidf]

Originally Posted by ls1nova71

Does the engine have 706 heads? If so, could be a set of Castech heads that were known for cracking.

Also, the '98 coolant temp sensor may move the gauge in a '72, but won't be accurate. Tried that 20 years ago on my '71 Nova, which I'm sure uses the same internal gauge parts and it didn't work.

No, 862 heads. Could not find the Castech foundry mark. Part of me is starting to wonder if I have a head gasket leak. I think I will pull the heads, inspect and then take the heads to the machine shop as I will want them freshened up regardless. The shop can pressure check them for me.

[Davidf]

Update:

Machine shop said 862 heads passed pressure test, so I had the heads resurfaced and valve stem seals replaced. We both now suspect a leaking head gasket.

Over the weekend, I got the LM7 reassembled with new lifters, timing chain, and of course seals. I went ahead and painted the block Chevy Orange. I used an EngineTech gasket set and found that I did not trust the oil pump pick-up tube o-ring, so I purchased a replacement from a Chevy dealer. Also, the kit did not come with the oil galley expansion plug so that was sourced from the dealer as well.

I started on the engine wiring harness mods and received my computer back from LT1SWAP. The wiring is bit more complicated as I am keeping the a/c going through the computer (for idle compensation when compressor is activated) and the pressure safety switches.

Next up will be cleaning the transmission to get it ready to reattach to the engine just before I am actually ready to make the swap. My C10 is on the road currently, so I want to make sure I have most of what I need and all parts modified before I actually attempt the swap.

[Davidf]

Update:

Engine is done and fully assembled on the stand. Been working on the wiring harness and have the fuse/relay box 100% wired (included relays for A/C and Condenser fans. Spare relay socket for future radiator fans, if I go that route).

Now, reason for my post: What fuse size/amperage should be used for all the fused circuits? I followed lt1swap website for grouping systems on fuses. For instance:

Fuse 1: Coils and ECM/PCM keyed power (relay 1 controlled)
Fuse 2: Fuel injectors (relay 1 controlled)
Fuse 3: Transmission, MAF, (heated) primary oxygen sensors (relay 1 controlled)
Fuse 4: Fuel pump (relay 2 controlled) and ECM/PCM constant power
Fuse 5: A/C compressor (relay 3 controlled)
Fuse 6: Dual condenser fans (relay 4 controlled)

[Davidf]

An update for anyone that cares...

Over the weekend, my son and I got the '01 5.3L LS mounted in the '71 C10. As noted above, I went with the Hooker engine stands, F-body mounts, and Hooker transmission cross member. Let me tell you, the engine is a tight fit even in the seemingly large engine bay. I had to clearance the left frame rail to clear the power steering pump return line. Just past the pump (toward the rear) the frame narrows, so I just made the frame look like it narrows further forward than factory. If you did not know otherwise, you would never know I cut on the frame...nice clean line. I used the '01 Tahoe LS trans cooler lines and they will need a bit of rebending as they hit the front frame cross member. And, they are rubbing on the main cross member (tight fit here). But, I think I can make them work.

Now, as for the Hooker Blackheart engine mounting solution, I like it. But, the engine stands need a bit of quality control work as on one side, the ears on the stand was 1/8" too narrow. That meant grinding 1/8" off the mount bolt tube. The trans mount is a nice piece of hardware. The Hooker solution keeps the engine very low in the engine bay. As such, there is plenty of clearance for the a/c compressor, but necessitated the clearancing for the PS pump. Supposedly driveline angles are maintained. I also kept the truck oil pan and it clears the drag link by about 1/4"...works for me. Wire harness follows factory routing in front of oil pan, I got rid of the plastic factory bracket and camped the wires to the front oil pan bolts...perfect.

Only collateral damage was breaking the retaining tabs off the MAP sensor...dang, should have left it installed. I guess some cleaver zip tying will fix that problem. Probably only needs to be retained in case you get a intake backfire...otherwise, not sure how it would come out anyway.

The Trailblazer SS manifolds clear the frame fine without the need to do any frame clearancing.

Also, got new '87 C10 a/c evaporator mounted in air box (prior to installing engine). And, firewall has a fresh coat of paint...sorry it is all covered, but been raining in Central Texas a lot lately.

Now I get to start on the fun part...all the connections.

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