The Stovebolt Site Forums The Shop Area Engine Shop valve guides for "848" head

While removing all the valves on an 848 head, I discovered one intake valve guide to be seriously worn "oval shape" especially on the top side of the head. This wear is within 1/16" of the outside edge of the guide. I thought that these valve guides were an intergral part molded into the head, until someone told me that the whole thing presses out for replacement. Is that true? If not, what method do machine shops use to make repairs. Thanks

Like my grand-pappy always told me "you can lead a gift horse to the water....but you can't look him in the mouth"

Your valve guides are a "press fit". Your best bet is to take the head to a machine shop and have them recondition it for you. You can also have them "nuralize" the valve guides, but the one sounds to far gone for that. To do it yourself you would need a good press and know what you are doing. While your head is at the machine shop have them install hardened valve seats for you. They should manaflux the head as a matter of recourse.

Ron,

I have never done this before myself, but I have had a couple of heads worked on and always had the valve guides redone.

On the 292 head I had done a while back, the valve guides were knurled to improve tolerance, but the spark plugs also had covers on them to reduce oil fouling. My guess is that the guides were worn so bad that the exhaust resembled an insect fogger.

I don't know if they were bored out and new guides pressed in or ???

I do know that the new guides that were pressed in are an alloy that resists wear and oil migration better than the original guide material.

Another important factor when you are getting your head done is to make sure that you get hardened valve seats - AND - tell them you want the seats to be at stock heights. Some shops sink the seats deeper and this kills flow when the valve is open as well as then requires spacers under the valve springs to get proper compressed height.

You get what you pay for and a good and thorough head rebuild will cost a few bucks.

Knurling valve guides is for a cheapo build. You'll be smoking like Denis Leary during happy hour in no time. Guides are cheap, replace them. If you have to change everything, guides, valves, hardened seats, springs, locks, keepers, etc.. The total bill will be around $350-$500 range. Dropping a 40 year old valve into your engine will cost more than $500.

chip

I didn't see it mentioned but you will also have a choice of steel guides or bronze. For a street engine you will be happier with steel guides.

Gentlemen, my spelling of "Nurlizer" and "Nurlizing" have been brought into contention before. But, I used to own a Nurlizer and also a Manulathe, along with a tri-bevel valve grinder and hard seat grinder. I was pretty certain in what I was doing with the equipment and how to spell "Nurlizing" and what it did for your valve guides and pistons. So, having seen that you felt it needed a "K" in front of the "N" I finally went looking for my Service Manual for the "Nurlizer" made by Perfect Circle that I used to own. I have a couple of pictures to share showing the machine and what it does for a piston. It will also help to "Nurlize" your valve guides.

Perfect Circle Nurlizer

cutaway of piston

Piston that has been Nurlized

Thanks for your time and replies. I'll take it to a machine shop.