Engine Top End

[06T200]

I got a spring compressor off of ebay pretty cheap. I would get one, these springs are TOUGH!

+1, it would be nuts to try and free hand these bucket style heads, I would go nuts trying to find keepers every five seconds. lol

[xintersecty]

Sucks about the keepers, looks like you are on the right track. I feel helpless for the most part since my tooling is thousands of miles away lol - Don't forget you can always just kiss the seats with stones after just to true up the seat, the angle cuts can just float if needed. - I would just see how they lap on the seats with compound, or use the blue die and 'slap test' to see where it is landing, to see how far off they are. Best advice I can give is be VERY careful with the seats, you need them wide enough for heat transfer, be sure to hold any widths of the seat faces. I was hoping you would find a shop with the cutters needed - even if they just hit the valves with new guides like I did.

I end up doing nothing. I just lapped the valves. I got a pretty good fit. I left my valve guides alone, the seats looked great and I need to post more pics.

[06T200]

Ahhh, the old revered 'slap, lap and ROLL!!' method. Me likes, only if the intakes - did you have any broken exhaust guides? (pardon my old anal machinist concerns) As in, to soak in too much heat/hot spots thereby galling your new valves in short order? Just don't want to see you have to pull the head for a while, I know what a pain in the ass that job can be.

[xintersecty]

no exhaust guides where broken on examination. I hope. So maybe this will be ok or not.

[xintersecty]

Ahhh, the old revered 'slap, lap and ROLL!!' method. Me likes, only if the intakes - did you have any broken exhaust guides? (pardon my old anal machinist concerns) As in, to soak in too much heat/hot spots thereby galling your new valves in short order? Just don't want to see you have to pull the head for a while, I know what a pain in the ass that job can be.

I was thinking about this. I think I do have a bad guide. I might have over looked at put it as carbon on the guide. So your saying if the metal is not uniform, the guide will not transfer the heat correctly and then do weird stuff causing a failure, right?

I am going to take that valve apart and take a picture.

[06T200]

X,
I have seen broken/cracked guides live in an intake port fine (cooled by the incoming air/fuel), but I have never seen a fractured guide live long in the exhaust port. The reason, is the crack or break will usually create a 'hot spot' (as in hot enough to melt the steel!) that will heat soak the valve something fierce. Something to keep in mind, the exhaust valve relies HEAVILY on the guide as a means to transfer heat into the head itself, and thereby cool the valve. Keep in mind the valve is opening/closing hundreds of times per minute, even in perfect conditions (good guides) it is amazing they can work at all considering the heat induction cycles they live in. So any damage to the guide(s) that increases the surface area will soak in more heat, and any more heat is (my guess) too much heat for good long term reliability. I would think the valve will burn (eventually) if it can't cool as designed.

This is going from my own experience of clapping valves in race engine applications and attempting to run cracked guides, and quickly galling the valves which dropped the entire guide and destroyed even more parts. Since then, I have always had to deal with the new increased surface area of broken guides. In some race motors I have had success just grinding the broken part flush with the port wall and call it good, but this was an engine meant to travel 1/4 mile at a time, and reliability was not an issue.

For good reliability you need the valves to be able to cool themselves as engineered, so just something to keep in mind. - Trust me, if I thought I could throw my rig back on the road with broken guides I would have done it. Im cheap! But I know this won't last in a daily driver/commuter application for very long, assuming any are broken/cracked.

Use your best judgment, but understand these little valves already live a hellish life even in perfectly machined conditions with no cracked guides.

[xintersecty]

X,
Use your best judgment, but understand these little valves already live a hellish life even in perfectly machined conditions with no cracked guides.

Your advice is well heeded. Going to take pic and get it replace. Thank you very much for taking the time to write that.

[xintersecty]

k, got a picture of the valve guide.


OK, I had asked about ordering tools to ream the guides once replaced. So if can throw some advice my way take a look at this post
http://www.aveoforum.com/forum/f82/e...tml#post197739

[06T200]

Yes, 6mm (.236) is the correct ID you are shooting for on all guides. 6.02mm being the limit of wear. We used a goodson 6m reamer on mine, but any good reamer will be fine. If you have a pneumatic driver they should pop right out with a few zaps. Or use a brass stepped punch to hammer out/in. If you get a stubborn one, heat the head up to expand the material a bit. Again make sure your new valves seat correctly afterward, and true up as needed. The smaller OD of the exhaust valves is to account for their heat load and expansion, they run pretty hot.

[06T200]

X, if that is the only damage to the head, you lucked out. Just swap that cracked one out and you should be good as it was when new.