400 stroker rebuild makes noise

[ZANYZANGY]

A friend of mine built a 400 stroker when you start it up it radels like a diesel till it warms up . He took the moter back apart could not find anything wrong. has anyone had the same problem?

 

[Cranky]

Piston slap? How loud is it and what part of the engine is the noise coming from?

 

[super-bee_ski]

Lifters
Could be:
1. Mis-adjusted (LOOSE) Valve train
2. Inadequate oiling to upper end

 

[Jackpot50]

How much piston clearance?
What type of lifters?

 

[beezee]

Take a look at the pistons to make sure the valve reliefs are properly placed and look carefully at the pistons to make sure no contact. Buddy of mine had 4 pistons in wrong and the valves were hitting until 1 dropped. Sounded like a rattling noise in the heads.

 

[69Bee]

Also make sure the oil pickup is not hitting a throw on the crank.

 

[lewtot184]

pistons with straight pins and probably a little too much clearance will rattle. hypereutectics will really rattle if they're too loose. as long as the noise goes away when the engine warms up i wouldn't get my panties in a bunch over it. typical of hi-performance/race pistons.

 

[Meep-Meep]

2618 alloy pistons or loose piston to wall clearance. If 2618 then it's normal but not built to run 100K miles. If loose clearances with the 4032 alloy then you have a problem.

 

[Rocketman]

if it has adjustable rockers they could need realignment as well

 

[383man]

pistons with straight pins and probably a little too much clearance will rattle. hypereutectics will really rattle if they're too loose. as long as the noise goes away when the engine warms up i wouldn't get my panties in a bunch over it. typical of hi-performance/race pistons.

This is correct. If it sounds like a diesel but goes away after warming up then its piston slap. Once the pistons exspand some it has less piston to wall clearance and the noise will go away. Its normal for many high performance forged pistons that exspand alot more then cast pistons so they run alot more piston to wall clearance. Normal stock type cast pistons can run around .001 to .002 and good forged pistons can run .004 to about .008. Mine do it a little as I run about .005 piston to wall clearance in mine. Many pistons are cam ground where the skirt is actually not completly round but as the piston heats up and exspands the piston skirt will become round and take up the clearance.
But as was said if its not to bad and goes away you should be fine. Ron

 

[dink]

I build them loose so that I don't have pistons getting tight at highntemps... But they make a lot of racket cold... Its a good idea to pull the oil pan every oil change to look for broken skirts... So they don't plug up the pick up ... A few broken ones won't hurt anything... Rember its a full on race motor not Nana's grocery getter... I like to run at 230°