5.7 build sheet

[Bryan Dees]

Ok so I have a question for the engine builders. I currently have a 94 and a 92 both with 5.7’s. The 92 has a suspect spun rod bearing and the 94 runs great. I’m about to pull the 92 and do a rebuild, and had plans to LS swap the 94. After some thought I felt that for headache reduction, when I pull the 92 I could build it and place it in the 94 instead. It’s my understanding that the 92 should already be machined for a hydraulic cam where as the 94 is a flat tappet setup.

Now that I have completely bored everyone to death, my question is, does anyone have a build combo for a 92? I would like to remove the TBI and go with an EFI setup (if that’s possible), new heads, big cam etc. I’m basically wondering if anyone has done these things, and what combination of parts have you used?

 

[Schurkey]

I currently have a 94 and a 92 both with 5.7’s. The 92 has a suspect spun rod bearing

Be sure to inspect the flexplate. They're known for cracking and they sound like a rod knock.

It’s my understanding that the 92 should already be machined for a hydraulic cam where as the 94 is a flat tappet setup.

Both have a flat-tappet cam, both should be able to be converted to OEM-style hydraulic roller.

 

[Bryan Dees]

Thanks for the info Schurkey.

It doesn’t have a knock, it has an intense his pitch squeal after it runs for maybe 45 seconds.

 

[Schurkey]

Thanks for the info Schurkey.

It doesn’t have a knock, it has an intense his pitch squeal after it runs for maybe 45 seconds.

More likely a vacuum leak. Faulty PCV valve? Intake gaskets that don't seal on the valley side?

 

[RichLo]

A continuous squeal means something external is wrong. As Schurkey said, check vacuum first. It would suck to do a complete rebuild because of a dry cracked $0.25 rubber vacuum line.

A spun rod bearing would sound like a rod knock because that's what it would be doing, knocking the rod against the spun bearing, lol.

 

[Bryan Dees]

Good info guys. I already had the thing ready to pull. Was going to snatch it out tonight. I bought the truck as a donor for my 94, never could sell it because of the squeal.

Maybe I will connect all the wiring back up and fire it up and see if I can figure out what’s going on before I pull it and build it.

Still thinking of building one of them for my 94, I’m just not sure what will work and what won’t. Can I go EFI, vortec heads, big cam etc?

 

[JCribb]

Still thinking of building one of them for my 94, I’m just not sure what will work and what won’t. Can I go EFI, vortec heads, big cam etc?

Yes you can go vortec heads, I have them on a .040 350, small cam (mellings MTC-1), full tbi mods, shorty headers and an unrestricted exhaust. If you stay with TBI you have limited options for an intake manifold. I have the GMPP tbi/ vortec intake on mine and it was $400 just for the intake. I read you can use a regular intake manifold with an adapter for the TBI, but I don’t know for sure.

My engine is certainly a torquey sucker because it has trashed three NV3500 manuals, so far the NV4500 has been the cure.

If I ever tear into mine again, I will just go to an mpfi like the FAST self learning setup. The tbi is easy, but limited on tuning availability.

 

[Bryan Dees]

Yes you can go vortec heads, I have them on a .040 350, small cam (mellings MTC-1), full tbi mods, shorty headers and an unrestricted exhaust. If you stay with TBI you have limited options for an intake manifold. I have the GMPP tbi/ vortec intake on mine and it was $400 just for the intake. I read you can use a regular intake manifold with an adapter for the TBI, but I don’t know for sure.

My engine is certainly a torquey sucker because it has trashed three NV3500 manuals, so far the NV4500 has been the cure.

If I ever tear into mine again, I will just go to an mpfi like the FAST self learning setup. The tbi is easy, but limited on tuning availability.

Thanks for the info!

I’m not going to be doing anything to the 92 engine. I put it back together, found the squeal and fixed that, then I was able to hear the knock in the bottom end.

Tore it down and found spun rod bearings, and three spun mains. Check the photos of the block, crank and mains.

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[JCribb]

Holy hell that is some damage!!

 

[Bryan Dees]

Holy hell that is some damage!!

Worst I’ve ever seen. You can see the discoloring on the block where that main got super hot. I’ve never seen one crack the block under the main bearing either.

I knew that’s where the issue was when the bolts on that one main cap were only finger tight.

So now I have heads and a trans for sale lol.