Valve guides replacing

[Dave swMN]

The head from my own engine has a rough cam bearing and one bad lobe on the cam shaft. Bought a used head and cam shaft. The newer head has one valve guide that has part of it broke off (1/8 inch 1/2 of the diameter one the end away from the valve head). The motor had run with the guide broke as there is carbon build up on it.

Another problem (?) is that the broken guide slid out of the head easily and slides back in up to the retaining clip.

After reading the service manual it looks like I have a tough fix or is it no fix?

[Sam Green]

Originally Posted by Dave swMN

The head from my own engine has a rough cam bearing and one bad lobe on the cam shaft. Bought a used head and cam shaft. The newer head has one valve guide that has part of it broke off (1/8 inch 1/2 of the diameter one the end away from the valve head). The motor had run with the guide broke as there is carbon build up on it.

Another problem (?) is that the broken guide slid out of the head easily and slides back in up to the retaining clip.

After reading the service manual it looks like I have a tough fix or is it no fix?

It can be done but it's better if left to a head shop.
If the old guide don't come out clean, you could end up having to have over size guides made and you will end up taking it to ahead shop in the end and will cost you more.
If you do manage to change the guide without making a mess of it, the guide has to be reamed out to the correct size for the valve.
Re reading your post it sounds like you need an oversized guide to start with.
Hope you didn't pay to much for the spare head.

Sam.

[Jetblackchemist]

I'd take Sams advice personally. But another possible option, if you don't want to go that route...might be to get a new guide, fill the guide hole and coat the outside of the guide with loctite and shove it on up in there... here's a thread about people that do just that.
http://www.homemodelenginemachinist....c=12577.0;wap2

[Spokes]

For kicks & grins measure the outer diameter of the loose valve guide. I have a used guide salvaged from a CA95 head. We can compare the measurements. Maybe someone installed the wrong guide years ago. Can't hurt to check. I have never seen a loose guide in a CA95 head.

I use heat to destroy a loctite secured nut. I am not sure about securing a loose internal engine part with this product. I think heat and combustion by products would destroy the bond. Just an opinion.

[65Honda]

Spokes,
I've got some experience using red loctite on engine assembly. Provided the parts are clean before application it works just fine. I know an engine builder that uses it on connecting rod bolts and they claim that they've never had an engine fail due to rod bolts. Just my two cents worth....

Jim

[Spokes]

Point taken. Don't get me wrong. The thought was using a material to adhere a part that is normally pressed in sounds risky. No biggie.

[Jetblackchemist]

I had the same thoughts at first, then discovered that when you take it in to get fixed, there's nothing keeping the the guys at the shop from doing the same thing when you take it in there.

I found from researching the compounds, that many shops do exactly that...put on the compound shove it in, then write you a nice bill. So I posted it as an option, since many shops do this with sleeve retaining grade loctite or permatex.

I figured if many do that already, then just cut out the cost and niddle man and diy. Asking a shop how they attach the valves is also my advice, if someone chooses to go that route.

I saw a documentary about either Ferrari or Lamborghini motors some years ago, can't remember which, but I did remember how they put the guides in. They heated up the head and used liquid oxygen on the guides and inserted them at exact tolerance. It was pretty cool.