500 hp Valve Spring Broke with 6 hours on it?
 

Any ideas? Just had rebuilt from the ground up 500 hp EFI and broke an Intake valve spring yesterday in Key West. Motor was running great and then started to load up the plugs. Changed the plugs and ran great for an hour then just stalled. Was told could be a map sensor so I unpluged and it ran ok but heard the dreaded valve spring rattle. Pulled the valve cover anf the # 2 cylinder on the inside has a broke intake valve spring? Any help? Can i replace in the boat with air and a spring compressor? HELP!!!!!!!

could be a lot of things? need to find out what caused it.

but a quick fix you can put one on it in the boat.They make a compressor to do it on the motor and fill the cylinder with air .

what springs?
Most people are using Comp 929 set up at 1.880 around 145.


Guessing

coil bind?
Innerspring broke?retainer’s inner step too tall.Inner spring has more coil bind than the outer spring?
defective spring?
retainer hitting valve seals?
harmonics?
heat,no oil up top?



http://www.compcams.com/information/.../ValveSprings/

:D

[YOUTUBE]http://www.youtube.com/watch?v=i_NpzU4pGjc[/YOUTUBE]


Float
[youtube]http://www.youtube.com/watch?v=_REQ1PUM0rY[/youtube]

GoFastSonic,

Rob has hit the nail on the head.

Check springs for discoloration and/or cracks. If you do find a break that is jagged, that is due to harmonic resonance. A clean break is a sign of improper heat treat.

This will define if you have a materials problem or spring/setup issue.

Bob

Hell Bob I just was talking out of my ass:rolleyes::D


Good info:ernaehrung004:

Spring
 

Thanks guys will be pulling it apart this afternoon and will post findings

Couple things-

You can make do with a swap but you'll want to re-shim to proper seat pressure at some point. You can use air but I always use the rope thru the plug hole trick as a backup.

I've had valve springs and other things break in just a couple hours. All it takes is a nick and a crack and failure isn't far behind.

springs
 

What are the chances that nothing else got broke?

You could have floated the valve and bent it...hopefully it didn't kiss the piston.

Spring
 

Was doing alot of ideling around as patrol boat for SBI So hope all is well. Just cant believe a brand new motor. Talk about bad luck. First the race boat now my baby.