View Single Post
  #10 (permalink)  
Old 06-08-2020, 08:23 AM
eschaider's Avatar
eschaider eschaider is offline
CC Member
Visit my Photo Gallery

 
Join Date: Feb 2006
Location: Gilroy, CA
Cobra Make, Engine: SPF 2291, Whipple Blown & Injected 4V ModMotor
Posts: 2,647
Not Ranked     
Default

Steve, if you can wiggle the valve, the guide is history and needs to be replaced. Any time you replace guides you must do a fresh valve job.

Bronze guides are great for race engines not so much for street driven cars — their service life is too short. The OEM cast iron and powdered metal guides are often looked down upon because they seem to be lesser versions of the desirable bronze race style guides. They are not lesser versions. Those OEM material choices have a porosity that holds oil for lubrication which provides a longer service life for the guide.

Over the years there have been three different materials I am aware of that guides for street driven vehicles have been made from, cast iron, meehanite iron, powdered metal. I am sure there are probably others I am unaware of. All three of these materials are porous to oil (some more so than others) and will provide good service life for non race applications.

The first two are both cast iron although the meehanite iron is frequently used for high precision components. The powdered metal is the style used frequently today and is a very good daily driver sort of choice.


Ed
__________________


Help them do what they would have done if they had known what they could do.

Last edited by eschaider; 06-08-2020 at 04:09 PM.. Reason: Spelling & Grammar
Reply With Quote