Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Help With 406 Engine Build
View Single Post
  #35 (permalink)  
Old 09-03-2008, 03:35 PM
F-BIRD'88's Avatar
F-BIRD'88 F-BIRD'88 is offline
Yada Yada Yada
 
Last photo:
Join Date: Oct 2005
Location: Ontario, Canada
Posts: 9,153
Wiki Edits: 0

Thanks: 5
Thanked 380 Times in 374 Posts
Well the dip stick being pushed out of its tube at WOT (assuming you have sufficient valve cover breather capacity) indicates that there is a lot of pressure in the crank case. This is caused by excessive blowby past the rings. Blow by is an indication that the rings are being upset. A major cause is detonation from excessive compression ratio and low octane fuel.
This detonation eventually (doesn't very take long) damages the pistons rings and the piston ring lands (distortion) and piston ring/cylinder wall seal.
The motor becomes an "old, worn out motor" before its time.
Other possible causes are incorrectly installed piston rings. incorrect second ring end gap, scuffed rings or piston skirts. insufficiant valve cover venting, preventing the piston rings from sealing on initial engine breakin, or fuel wash damage of the cylinder walls. (excessive fuel flooding wash past the piston rings { washes the oil off the cylinders allowing metal to metal contact ( scuffing)
A cylinder leak down test will verify this. If the piston ring lands are not damaged/distorted and the piston skirts are not scuffed, then a rering with cylinder rehone often will restore the combustion seal quality.
If the cause is not corrected then the damage and ring seal failure will quickly reoccur.
The pistons and rods would need carefull inspection. Often detoantion will distort the piston pin hole diameter and rod big end diameter as well as kill the bearings.
Another possible cause of poor ring seal/blowby is a bent connecting rod.
This is why I warn against building with excessive compression ratio on street pump gas motors. Its very expensive to fight the laws of physics. Much cheaper to work within these laws in the long term.

I like to add a moly lube treatment to my new engines to treat the internal parts to help prevent metal to metal scuffing.
www.molyslip.com

Last edited by F-BIRD'88; 09-03-2008 at 03:50 PM.
Reply With Quote