what's with terrible new valve guides?

[lvporschepilot]

I've been noticing new valve guides seem to be made in a hurry lately and I'm having to throw away about 1 of every 10 I get.

I find it common that the nose of the guide already has .003+ clearance (after pressed in place obviously) whilst the center portion offers correct tight clearance which obviously needs honing to fit to the valves. What this has been doing is allowing the center of the guide to be honed to correct specification while the final .250 or so completely out of whack allowing the valve to have excess 'wiggle'. I wouldn't so much mind the .003 or so clearance already there if there were a honing tool that guaranteed I only honed a tiny portion of the guide! Such a tool of course doesn't exist, although I have tried honing a couple using a 240 grit 8mm guide Flex Hone (fantastic tool btw) as they remove less material per pass. No go though, same result. The only option is to remove and hope the next one is decent.

Needless to say this has been driving me nuts as the only 100% sure fire way to check this is after the guide is pressed into the head.

I just installed a set of guides into a Ferrari Dino head and 3 of them were like this! They all had about .009 wiggle measuring about 1 inch from the guide. Totally unacceptable, and they are from a guide manufacturer in the US who I also use for Porsche guides.


I think what's happening is the guides are being drilled too quickly which results in the first .250 or so of the guide having more material initially removed than the rest of the guide. This is massively stupid and frustrating.

I can't be the only one seeing this nonsense.

[Walt Fricke]

An engine builder I know just makes his own guides. He looked into the material used in air cooled aircraft engines for this purpose, and buys that in rod form and uses his lathe. His prices don't seem that much higher (though I didn't do a careful comparative study) than other shops would charge to install new guides, so the machining may not be all that tricky or time consuming?

I'm confident I can pull guides, but don't have a lathe so have never tried to install new ones myself.

[cgarr]

Who is the MFG? I have never had a guide over spec after installed and I use about .0015 to .002 interference fit, but they are checked before installed. I have had guides bored of center before.

[lvporschepilot]

I think that's what I just might do Walt, have them made by someone who knows and will do it right every time. Typical Ferrari valve guides cost $15 a pop so I don't that or even a bit more if it means I don't have to monkey around with this any longer. Glad I'm not the only one seeing this....

[Ken911]

xtreme makes thier own guides I think for the same reason might want to contact them. Xtreme Cylinder Heads And Castings

[lvporschepilot]

thank you. calling them now

[safe]

Many builders around here uses "sleeves", or what they might be called, what do you guys think about them?