My project...

[no cigar]

Knocking in new engine... Help!

Hey guys just thought I'd share my project. It's a rebuild of the Vortec 5.7 in a 99 2dr Tahoe. This was a budget build and I reused a set of pistons and rods from a grand sport corvette. Pairing that with an LT4 hot cam and ls6 valve springs. All in all its been a fun project with the exception of having to helicoil the crank.



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[retorq]

Those sure are short skirted pistons.

 

[saif najd]

Nice, please keep it up

 

[no cigar]

Yes they are short skirted. I'm thinking that the stocker that's still in the truck and broken may become a 383. Picked up some SP hypers for $50 bucks on CL. Just need a good set of Vortec heads and might do an E85 beast.

 

[retorq]

I think I'm gonna go with the bowtie vortecs on my next old school sbc build. Just like the vortecs only more better.

E85 is rare here and costs the same as low grade so its not worth it for the cost savings.

 

[no cigar]

Nah not in it for the cost savings. I want the compression

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[retorq]

The block that is in the Tahoe now will come out and be my next race engine, I thought about doing alcohol on that one but .... guess well see.

 

[no cigar]

So we finally got it all together and R&Rd and on first startup purred like a kitten. Idled it around a little bit and let it sit until the next day. Started it up and once the lopey idle subsided and the RPM stabilized it developed a loud, high frequency knock on the bottom end. Not a solid knock like a rod or piston, but a tapping. Very hollow, tinny sound. Almost sound like the crank is striking a baffle or windage tray.

In fact it sounds identical to the sound I had when I accidentally put a jack under the oil pan of my mustang and pushed one of the baffles of the pickup tube about 1/4 of an inch into the path of the crank.

This is the oil pan I am using:
http://www.summitracing.com/parts/sum-g3503/overview/

Windage tray is stock, pan pickup is new OEM unit. Anything come to mind? It's definitely coming from somewhere in the pan/bottom rear of the engine. In fact the mechanic thought it was the torque converter.

 

[99Vortec]

And it's not a connecting rod bearing problem?

Those initially start out very slight sounding.

 

[retorq]

Flywheel is in good shape and not cracked anywhere?