GM 5.3L LM7 in 79 C20

[CheyenneC20]

I have just swapped out the 454 big block and turbo 400 for a 01 Silverado 5.3L LM7 with 4sp 4L60E. It goes great, pulls as hard as the old 454. I need info on pulling the injectors as the engine has 120 miles on the clock and I want to service them. Can anyone help?

[Thealien]

Shouldn't need to service injectors with 120 miles (or is it 120,000?)

You need to release fuel pressure (be carefully). There is a shrader valve that lets you check fuel pressure on the rail (also a way to bleed pressure, again be carefull it is under high pressure).

You might be able to pull the pump fuse and run the pressure down? I bled mine at the shrader valve.

You can then disconnect the factory flexible fuel feed from the rail (need a special tool about $5 at most parts stores). I left mine connected.

There are a couple of small bolts that hold the fuel rail down. Once you remove those the whole rail with injectors can be pulled up (may have to unplug the injectors first) Do not mix up the injector plugs.

There is a little clip that holds each injector to the rail. Once that clip is pulled/removed the injector can then be pulled from the rail. Sometimes it can take a little effort to remove the injectors/rail from the intake and the injectors from the rail (fuel varnishes and they stick).

When reinstalling or installing new I read a little gas on the orings helps to install them.

I did all 8 of mine with the rail attached to the fuel line one at a time in about an hour and had never done it before.

[CheyenneC20]

Hi There,
Thanks heaps for the info. The engine has done 120,000 miles. It runs great. I am giving it a total service to have a base line on it since it has just gone into my C20. i have relaced the fluids, and all filters and spark plugs, so the only thing left was to service the injectors. I am amazed at the performance of this little engine compared to the big block. My C20 is a Camper special, with a Brahma canopy, and tips the scales at 2 1/2 ton empty. Was doing abt 8mpg on city driving which has increased to 16 - 18mpg. I thought the little engine would struggle in the C20, but it amazed me with how hard it pulls. I don't miss the big block at all, especially starting from cold. The little LM7 fires right up and performs effortlessly when cold. Overall it was a very successfull swap.

[gchemist]

Please post pictures. I would like to see it!!

[Matt Man]

Originally Posted by CheyenneC20

Hi There,
Thanks heaps for the info. The engine has done 120,000 miles. It runs great. I am giving it a total service to have a base line on it since it has just gone into my C20. i have relaced the fluids, and all filters and spark plugs, so the only thing left was to service the injectors. I am amazed at the performance of this little engine compared to the big block. My C20 is a Camper special, with a Brahma canopy, and tips the scales at 2 1/2 ton empty. Was doing abt 8mpg on city driving which has increased to 16 - 18mpg. I thought the little engine would struggle in the C20, but it amazed me with how hard it pulls. I don't miss the big block at all, especially starting from cold. The little LM7 fires right up and performs effortlessly when cold. Overall it was a very successfull swap.

That motor will have more hp but less torque

[CheyenneC20]

I don't know how to post the pics