Engine knock

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oley340

oley340

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Looking for help or opinions... i have 340 stroked to a 416 as of late on start up it has developed a loud clanking sound that lasts around a minute or so. after that it is fine no power loss. Any help on this matter would be great Thanks
 
Could be piston rock/slap. Classic on a stroker engine. The short forged pistons tend to rock in the cylinder and make that noise. After they warm up the clearance is taken up and the noise stops.
 
Clanking - like a metallic sound or more of a knock like you'd hear on a wood door? Pistons don't "ring". If it's more metallic ringing i'd look elsewhere.
 
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oley340 said:
Looking for help or opinions... i have 340 stroked to a 416 as of late on start up it has developed a loud clanking sound that lasts around a minute or so. after that it is fine no power loss. Any help on this matter would be great Thanks
Click to expand...

If an automatic the VERY FIRST thing to check is the converter bolts.
It's common for loose bolts on the converter to sound like a knock, AND really common for it to go away after the converter starts warming up.

If a stick, flywheel bolts can come loose and sound like a engine knock.

If that ends up being what it is blue Loctite keeps that from happening again. (usually):D
 
While you're there, check for wasted lifters. Seems like every chevy I own develops a tick that goes away after about 10 min of driving
 
Well, a clanking sound sure is different than a tick from a lifter?
OP needs to describe better... where does it originate, give us an audio...
 
Thanks guys gives me a lot to look at
 
TrailBeast said:
If an automatic the VERY FIRST thing to check is the converter bolts.
It's common for loose bolts on the converter to sound like a knock, AND really common for it to go away after the converter starts warming up.

If a stick, flywheel bolts can come loose and sound like a engine knock.

If that ends up being what it is blue Loctite keeps that from happening again. (usually):D
Click to expand...
I will check that Thanks
 
Turned out to be the harmonic ballancer had seperated thanks for all your help.
 
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