I'm helping my son rebuild his 4.6L engine and have a question about the valve guides. He took the heads to a machine shop for a valve job but then bought Trick Flow cams a new set of Trick Flow valve springs. The new springs came with valve guides and I'm pretty sure they're much better quality than whatever the machine shop pressed in. They even look like better quality and seem to have less play in them. So I called around to find out how much it would be to just have the valve guides replaced and was told that anytime they're replaced, a new valve job needs to be done, even if one was just done. That sorta made sense at the time, but the more I think about it, it doesn't. Anyone know anything about this? And if he does need to get yet another (not cheap) valve job, can you explain why it's needed? I mean new valve guides should be positioned exactly where the old ones were, and since the guides have slight play in them, I would think the valves would still seat properly. But what do I know, I'm an old school engine guy. This modular engine is all new for me! :)

Thanks in advance!!
Brian

 

Take those valve guides that came with the spring kit and set them on a shelf. You've already dumped the cash for new valve guides, the ones that came with the springs may be a little better but the difference is negligible if any at all. Id go ahead with the build using what the shop installed. As far as dong another valve job, I cant see a reason for it, maybe they meant they will have to bore the guide bores in the heads since some aftermarket guides have a bit larger OD.