How to Reseat / Lap Valves (Basic Valve Job)
In this video i'm explaining how to reseat or lap valves in a flathead or overhead valve engine. Also can be called a valve job, but this is not a complete valve job. I also used to much valve grinding compound, it does not require a whole lot. Usually when a engine needs this done is when a engine has low compression that is found to be leaking around the valves, or sometimes a engine will backfire do to the valves not closing completely/properly. Thanks for watching.
Cylinder Head 105 - Valve Job Basics
Valves not sealing? Valves not bent? This is how you fix that problem. In this video I outline the basic valve job procedure. Cleaning the valves, cleaning the seats, cleaning the combustion chamber and lapping the valves in to make a better seal. Here I cover the process start-to-finish. It's the same exact process for pretty much all non-rotary combustion engines. It takes patience and perseverance to do this job, but anyone can do it. Reference your service manual for measurements and service limits. Everything else that's not in your service manual is in this video. I apologize for not having broken busted crap to work with in this video. It's more beneficial to all of you when bad fortune falls on me because it gets well documented, and many people watching these videos are looking for answers. If you have bent valves, you will discover it quickly once you chuck one up in the drill. You'll see the face of the valve wobble around while it spins. You'll see evidence of this damage on the valve seat. If it's bad, you may see damage on the valve guides in the form of cracks or missing pieces where the valve guides protrude through the head ports. Give all that stuff a good visual inspection. ...and if you doubt yourself, never hesitate to get a second opinion or consult a machine shop. They will have access to expensive tools that you wont find in your average gearhead's garage.
Cylinder Head 201 - Radius Cut Valve Job
This video covers the complete valve job process that your machinist might perform. If the 100 series videos didn't help you identify and correct a problem with your cylinder head, then this is the next step. This video is brought to you with permission from my machinist in full 1080HD, and covers cleaning up the head inside and out, preparation and setting up a radius cutter, cutting all 16 valve seats, valve grinding, and spans 3.5 hours of actual work in under 30 minutes. There's nothing like this anywhere else on YouTube. THANK YOU BALLOS PRECISION MACHINE. Thank you for the professional explanation and execution of a job excellently-done, and un-precedented access to your facilities. A valve job is done by re-grinding or replacing valves, and then having new seats cut to match the faces of the valves you're using. There are several different machines that might be utilized to achieve this result, but the process is the same no matter how it's done. There are seat cutters that utilize cutting stones. There are valve seat cutters with 3 separate angles installed 120° out-of-phase, and there are single cutters with all 3 angles (radius cutter) that cut with one blade in one pass. The machine demonstrated here is a Sunnen VGS-20 Radius Cutter. This machine (now out of production) produces a gradual curved seat that's superior to the shape of a traditional 3-angle seat. While a radius cutter does contain the 30, 45 and 60 degree angles, it does so without leaving any sharp edges between their faces. My valve selection includes Supertech 1mm oversized nitride-coated stainless steel undercut and back-cut intake valves, and 1mm oversized Inconel back-cut Exhaust valves. Inconel is a high-temperature alloy utilized in marine and forced-induction performance engines that can handle more abuse than steel can without melting. The other characteristics of the valves which are discussed typically yield bigger gains in airflow than simply using a bigger hole and a bigger valve. Why I did this to a perfectly-good cylinder head: I changed cams. Because the valves were previously recessed during another valve job 9 years ago, my valve installed height was increased and this raised the operating positions of my rocker arms. My new camshaft selection dictates using the stock valve install height. The only solutions to this valve install height problem are to either replace the valve seats, or install oversized valves. I opted for the latter.
Testing for Leaking/Bent Valves
--Please Read-- :) Some of the best advice I can offer you about fixing your car is to search for an online forum related to your car, or even for your specific engine. If you have a popular car or engine, this can be an amazing tool in diagnosing and fixing cars yourself! -------------------------------------------------------------- Directions 1. Get kerosene, gasoline, or break cleaner. 2. Tilt head on its side, with the ports of the valves you're testing pointing up and exposed. 3. Fill the intake or Exhaust ports with the liquid you chose, make sure to use enough liquid to cover the back of the valve head completely inside the port. 4. Look at the valve surface in the combustion chamber for leakage. (Let it sit for several minutes) 5. If there is a leak, you could have a bent valve or just a bad seal of the valve to the head. You might have to replace the valve, or just use some lapping compound to lap the valve/seat to resurface. 6. Repeat for the other side if you wish. 7. This is a great time to replace valve seals if you have noticed they are worn too much. 8. If you have any questions, please post them here and I'll try to answer them quickly. -------------------------------------------------------------- You just tilt the head on one side or the other depending whether you want to test the intake or Exhaust valves. I'm testing the intake valves in this video. I did this way because I didn't have the leakdown test equipment, but also because I wanted to replace my head gasket anyway. I wouldn't say this is the best way to test initially if you suspect leaking or bent valves because it requires you remove the head. Try just a regular leakdown test first. But if you're taking it off anyway it's pretty nifty and doesn't require the leakdown test tools. There are several methods to do this, this is just the one I chose in my situation.