5.3 LS Engine Swap into Ol’ Blue 1971 Chevy Truck Part 3


In part 2 we left off with the motor bolted to the trans waiting for me to build some motor mounts. Time flies because that was almost a month ago! In Part 3 I make the motor mounts, fix the gas tank, and make some EGR blockoff plates.

I started by disassembling the old motor mounts from the Big Block then chucking them up in the vice.

I started by disassembling the old motor mounts from the Big Block then chucking them up in the vice.

With the plasma cutter I torched off the old mount so I could re-use the tube that the bushings fit in.

With the plasma cutter I torched off the old mount so I could re-use the tube that the bushings fit in.

Next, I measured and plasma cut out a piece of 1/4" plate to attach to the LS engine.

Next, I measured and plasma cut out a piece of 1/4″ plate to attach to the LS engine.

I found and printed off some templates from http://www.diyautotune.com/tech_articles/ls_central/ls_motor_mount_templates.htm The only thing I didn't like about the template was how close the bolt holes were to the edge of the plate. So I left some extra steel top to bottom and extra steel width wise knowing I was going to have to extend forward to connect to my existing crossmember.

I found and printed off some templates from http://www.diyautotune.com/tech_articles/ls_central/ls_motor_mount_templates.htm The only thing I didn’t like about the template was how close the bolt holes were to the edge of the plate. So I left some extra steel top to bottom and extra steel width wise knowing I was going to have to extend forward to connect to my existing crossmember.

Take a Center Punch and make a mark for each of the 4 bolt holes then start drilling your holes.

Take a Center Punch and make a mark for each of the 4 bolt holes then start drilling your holes.

Always step up in drill bit sizes from small to large. I have my press set on the slowest speed and use lots of cutting oil to keep from burning up my bits.

Always step up in drill bit sizes from small to large. I have my press set on the slowest speed and use lots of cutting oil to keep from burning up my bits.

When drilling holes in two identical plates, I usually tack them together in 3-4 places with the welder so I can drill both at the same time.

When drilling holes in two identical plates, I usually tack them together in 3-4 places with the welder so I can drill both at the same time.

The DIYAutoTune diagram spec'd out 9/16" bolt holes which is what I used without looking at the bolts themselves first. In hindsight I probably would have made the bolt holes a size or two smaller.

The DIYAutoTune diagram spec’d out 9/16″ bolt holes which is what I used without looking at the bolts themselves first. In hindsight I probably would have made the bolt holes a size or two smaller.

Next I bolted the plates up to the motor and the assembled bushings into the crossmember. The next step is to attach the two with a piece of tubing. One side I coped with a hole saw and the other was cut off at an angle with the grinder. Tack it all together then carefully pull it out to final weld it.

Next I bolted the plates up to the motor and the assembled bushings into the crossmember. The next step is to attach the two with a piece of tubing. One side I coped with a hole saw and the other was cut off at an angle with the grinder. Tack it all together then carefully pull it out to final weld it.

I got a little excited and forgot to take pictures for a little while. But basically I disassembled the bushing and final welded the tube and plate. Then I cut a gusset template out of some cardboard, cut it out of steel with the plasma, and final welded it on also.

I got a little excited and forgot to take pictures for a while. But basically I disassembled the bushing and final welded the tube and plate. Then I cut a gusset template out of some cardboard, cut it out of steel with the plasma, and final welded it on also.

After letting the paint dry, lube and reassemble the bushings.

After letting the paint dry, lube and reassemble the bushings.

And bolt back in! (using locktite on the threads to make sure they don't loosen up over time)

And bolt back in! (using locktite on the threads to make sure they don’t loosen up over time)

Drivers side, same thing.

Drivers side, same thing.

So since I have a ’71 Chevy body on a ’74 Chevy frame with a ~’01 Chevy LS engine and already custom crossmembers I really had no choice but to make my own custom mounts. I was able to re-use my existing bushings which are just polyurethane spring bushings. Then the rest are some relatively simple pieces of tube and plate.

 

In addition to the motor mounts, I also fiddled around with my gas tank. The guy I bought it from had broken off the main plastic fuel hose connector. Not wanting to buy a whole new unit ($$$) I used a brass barb, some 100PSI rated fuel hose, and fuel injection rated hose clamps. If it doesn’t work, I can always go buy another one at the junkyard (I just don’t want to if I don’t have to). Here are some pics:

 

I also worked on creating some EGR blockoff plates. Of course I could buy some online, but in typical DIY fashion, I made my own.

Viola! Homemade and just shy of free EGR blockoff plates. Maybe they aren’t as perfect as a premanufactured piece, but I bet they will do the same job just as well. I saved money and learned a lot while I was doing it (which is the point of DIY Metal Fab isn’t it?????)

 

    Ol’ Blue LS Swap LINK INDEX:

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