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In any case, it is just a "coating" and would be removed by grinding, whether it's applied to the valves themselves or the valve seats (more likely). Modern valve seat materials are incredibly hard and durable, obviating the need for Stellite in the first place.
If you are replacing old valves with new you will most likely need the seats reground to match before lapping. The manual will show you how to do it if you have the proper tools to do it. I just pay my local machine shop to redo the entire head. For a 2 valve head they charge less than a hundred bucks to go through the entire thing, inspect ...
You'll really mess it up. A quick valve job to freshen up the seats is the most it will need. if you get carried away and create a groove in the valve, you'll be buying new valves as well as getting a complete valve job. As I said minor sweating around the valve is ok. You should have done a compression test before ripping the motor apart.
Learn how to properly grind valves. Use the correct techniques for valve lapping by machining them.
A cylinder head may need to be resurfaced; after welds or other repairs have been made; or milled to increase the compression ratio. The angle changed slightly to better align with an aftermarket intake manifold. So, whatever the reason is for cylinder head resurfacing, you want to do it quickly, efficiently and correctly.
Myth #8. Valve Jobs . Another question we get daily around here, "Do you do a radius valve job?" or "Do you do a 5 angle valve job?". A valve job is not just a valve job. You can't just throw any 5 angles or any angles at a head and expect results. Typically a valve job consists of 3 angles from the factory.
Do new valves need running in? ... but i do know when you're rebuilding the head they have to be "seated" so they fit perfectly. ... grinding, …
Another indicator would be any wear in the seat area or the stem of a titanium valve. When you're running titanium valves, you need to do much more maintenance on the engine to monitor these factors." Can you mix titanium intake valves and stainless exhaust valves? "Absolutely.
But others said seats in aluminum heads actually require less interference than those in cast iron. Ray English of Solon Ohio says he has been rebuilding aluminum heads for 15 years and has never used more than .005 in. of interference. "You really do not need any more than that. Most of the factory specs call for .003 to .005 in. of interference.
The block may also need new expansion plugs and oil galley plugs. You may find for sale complete cylinder heads (with related camshafts and valves found within), and you'll still need cylinder head gaskets, valve covers, valve cover gaskets, oil pans, oil pumps, harmonic balancers (if equipped), and timing covers.
If you are planning on also changing out the valve seals at this time, which I would recommend while your there, be sure to check out this article HERE on removing and installing valve seals. To Install . 1. Thoroughly clean all the carbon off of the valve before you install. Not that you have to do this, but you have the valves out and there ...
Any time you change the seats, re-grind the valves or put new valves into an existing seat, it's a good idea to lap them in and make sure they are seated. Since valve lapping paste is a highly abrasive pumice, there is a right way, and a wrong way, to do it.
If you want to do the job correctly, you will need to add in the cost of machining for new valve seals ($50/pair cylinder heads), the cost of the actual seals ($80/pair cylinder heads), and then a valve job and assembling each cylinder head ($200/pair cylinder heads).
For the most part LS heads are very good quality, you find that most (even higher mileage units) do not require a valve job. If you are swapping on a used set, and want to save some $$$ at the machine shop, here is an alternative for you. I hope this gives you an understanding of valve sealing, and saves you some money.
I have some used heads and the intake valves are a bit rough but may clean up if I lap them some. ... on a fresh vavle job i was taught to grind the valves and the seat 1 degree intereferance and lap the two together ... You almost always need guides...but engines do indeed manage to seat wonky valve action.
The opening for the valve should be round, not oval, not egg shaped. The valve stem, when inserted into the guide, should be solid and not able to be wiggled around. Too much free play and it's time for new guides as well. This spec is also in the manual and you will need a dial indicator to check the play.
1. new enlarged valves (2.02, 1.6) new guides and seals 2. enlarged pushrod holes 3. bowl blending 4. decked 5. modification on guide to accomodate .600 lift 7. I provided my own springs/keepers that they installed People that are paying more than $300 for a simple valve job need to go shopping.
Personally I would do a little bit of lapping with a fine paste when fitting new valves or new ... or head seat cutting machine as the grinding …
Grinding vs Lapping Valves. The purpose of grinding valves is to have the valve and valve seat make an air-tight fit.. The purpose of lapping valves is to see if that was done correctly.. If your cylinder heads were rebuilt at a machine shop, a specialized machine put a precise bevel on the valve and seat surfaces.
What You'll Require. To lap valves, you'll require valve grinding compound and a valve lapper, which is fundamentally a wooden dowel with a suction container on the end. In case you're checking the seal on a head that is simply come off from a vehicle, wire wheel the carbon and gunk off the head and the fixing range and the stem.
Grinding valve seats with abrasive stones has been aound about as long as the internal combustion engine. In the early days of grinding seats, there were only two abrasive materials to choose from – General Purpose and Finishing – because seats were mostly made of a single material, cast iron.Click Here to Read MoreAdvertisement Today, […]
You would use 'lapping compound' (strangely enough) available at most parts stores. Stick the valve in with just a little dab of compund on the face and use a 'lapping tool' (a small round wood handle with a suction cup) to attach to the valve. Lapping or grinding of new valves is NOT recommended anymore.
Pros Cons on not grinding valves at head gasket replacement? Is there a risk of early ring failure if you do it? Are the valve seals at risk and will fail soon? I would think the head will function better if the valves seats mate like new. I've been warned that it may cause ring failure and I shouldn't. Others obviously would do it.
Learning how to machine, install and grind valve seats; can help solve many, valve leakage and valve burning issues. The growth of the valve seats market can be traced, back to the early 1970s. This is when the switch to unleaded fuel took place. Most of the engines in use, had to have replacement valve seats; inserted in the exhaust side.
Do I need to lap new valves on a new head? I would of course if i had the compound but i want to avoid buying it if i don't need it. I tried to do the white board felt marker test where you put ink on the mating surface of the valve and see how much rubs off …
Even on aftermarket heads that come out of the box with a three angle cut, when you lap in the valves you'll see the angles haven't been placed for optimum performance. The graph below shows the results of a flow test I carried out on a brand new …
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