At What Point Is A Valve Job Necessary?

hoopty5.0 said:

Brian, I've been wondering if I should come up with a witty retort to your comment. I've decided against it. Instead, I'll ask the question again, but preface it with a statement.

- Outside of just getting a valve job because it's just a smart thing to do, what physical evidence would you find that would obviously point to you needing a valve job?

Since asking the question, I've learned that there are ways to test for seating and ways to lap the valves in a pinch, should that be your only option in a hypothetical world.

Anything else that should be added?

Click to expand...

There was no smart assed intent at all with my reply.

There's more to a valve job than just providing a good seal. The factory valve job on the Explorer heads is very basic and most likely little more than a simple 2-angle grind, with wide cut seats and faces. It's purpose is little more than to provide a leak free seal between the valve and the valve seat and a durable, long service life. A good 3-angle grind (or even 4 or 5-angle if you really want to get fancy) with narrower cuts and shallower angles can greatly improve cfm and velocity and low and mid lift levels and quite frankly should be mandatory for any performance engine.

Also, It's a good bet that if the heads have been sitting in that yard a while, or have been on an engine that has spent the majority of it's life driving short distances without reaching optimum temperatures, they've got a fair amount of pitting around the valve face/seats that should be ground out.

As noted by members previous, if there's any guide wear what so ever, having them replaced and the seats recut will be mandatory.

So while you "could" get away with not having them cut if the guides were in good shape and there was minimal pitting on the faces, I still wouldn't recommend it. You'll not only be leaving some performance on the table (on a set of heads that are only worth about 25hp to start with), but you've now spent $250+ (and presumably an entire afternoon) new valve seals, springs, gaskets, sealant, fluids, etc....to bolt on a set of heads with questionable valvetrain that without a doubt has got more miles behind it, than in has ahead of it.

How bad would it suck a year or so from now to pull your hair out chasing down a rough idle and reduction in performance, only to find out it's stemming from a valve train issues that should have been addressed before the heads went on?