What type of material to make a valve guide

[300TD4x4]

I need to make or resize some valve guides so I can run larger stem valves in a Ford turbo 4 cylinder motor running 25 psi boost. I tried to drill out one of the guides and it kind of cracked apart. Don't know what material it is made from but the head from which it came was from a 99 Ranger 2.5. Is bronze a suitable material or is there something better? If itt should be bronze, what type? Where can I get some? The OD is around .490 and the ID around .340.

Brian

 

[Mud]

Ampco 45 Bronze is a very good guide material.
http://www.ampcometal.com/en/index.php?page=a45ext&PHPSESSID=2d2894468f2845a8040aba17469ec827
Cast Iron or Durabar would be a natural choice also.

 

[300TD4x4]

Thanks. I'll check that out. It sounds like you are suggesting I should not just use any old bronze, like the 1/2" round bar stock I've got laying around.

 

[Forrest Addy]

No, plain old brass would be a bad choice for valve guides. Your application (high heat, reduceing atmosphere, poor lubrication, dry rubbing, heat transfer, low force reciprocation) requires a material especially suited for it.

Usually automotive engine valve guides are made of cast iron. Bronze works well provided you pick the right alloy and the interferance fit doesn't loosen up from the heat and the differentail thermal expansion. The only place I've seen bronze valve guides - aluminum manganese bronze - is in aluminum heads; never in cast iron.

 

[Hawaii Machinist]

Aloha,
In years past when I ran an Auto Machine shop, I installed thousands of Bronze guides in all manor of cyl. heads. IIRC, my source was Precision Engine Parts, or PEP, in Ca. somewhere. They call the material that they use "Bronzanium 90"
Link to their site is;
http://precisionengineparts.com/valve_guides.htm
Good luck
Doug

 

[Booger]

No need to reinvent the wheel.Just go to a auto machine shop and buy 4/8 guides.Cost you 10-20 bucks,depending on what you get.You can get them in bronze or cast.They will come with 1/2"od with .343 id.Get them long enough for your needs.Ream the head to 1/2" exactly,the press will be in the guide,ream ID to .3437(11/32).Your valves should mic out to .342 or so,maybe a little less.

PEP is in Las Vegas.

 

[300TD4x4]

Thanks. I did call a local engine machine shop and the owner did indeed say they probably have suitable guides there for about a buck and a half each.
Brian