You might recognize the name Jeff Huneycutt as an occasional contributor here at EngineLabs. We recently came across this video of his in which he details the process of rebuilding a set of junkyard cylinder heads on the cheap. While rebuilding a cylinder head might sound like something you wouldn’t want to pinch pennies on, Huneycutt shows what patience, elbow grease, and attention-to-detail can yield.
While he’s rebuilding a set of 6.0L LS heads (317 castings, to be specific) in the video, the following procedures and concepts are pretty universal to any cylinder head, be it aluminum or cast iron, and can be done with very few specialty tools, none of which will break the bank.
Checking Valve Seat Seal
“A proper engine shop would use a vacuum tester, but those are pretty pricey, so we’re going to get down and dirty with a go-no go test to see if the valves are still seating properly,” says Huneycutt.
With the cylinder head assembled, simply seal the chamber by putting a spark plug in the spark plug hole and get the head as level as you can. Then simply fill the chamber with some water. “If you’re checking an iron head or are worried about using water and causing rust in general, you can also use mineral spirits or denatured alcohol,” Huneycutt says. “If you have a bad leak, the water will run right out the port right away.”
Then with the chambers still filled, blow air into the ports with a standard air gun and watch for bubbles coming past the valves. “Don’t run the gun all the way up in the port,” Huneycutt warns. “Because that can actually open the valve if the springs are light enough, but just aim it into each port.”
Valve Stem Seals
“In my book, valve stem seals are consumables. You can take a chance on reusing them, but I have no intentions of ever risking it,” says Huneycutt. Removing the seals is accomplished by simply grasping them with a set of pliers and pulling. “Were talking low-buck rebuild, so you can probably get away with a standard set of pliers to pull the seals, but I love my seal removal and installation tool.”
Installing the seals can be done with a dedicated installation tool if you have one laying around. But for the budget-friendly option, a properly sized deep well socket will do the job as well. “Using a socket that drops right on the shoulder of the seal, you just tap it in, making sure to keep it as even and level as you can get it, square to the valve guide,” relays Huneycutt
Checking Valve Guides
Checking your valve guides is an important step, even though if the results come out poorly, there’s nothing you can do at home to rectify it. “You want to make sure that your valve guides aren’t worn. If they are, your low-buck rebuild has to go to the machine shop, and you start adding the bucks to it,” Huneycutt explains.
To test the guides in the head, you simply slide your valve into the guide, upside-down, and check for play. “If the valve wiggles, the guide is worn, and you have serious repairs ahead of you,” says Huneycutt.
Cleaning The Head Deck
In order to keep costs down, you want to try to keep the heads out of the machine shop, which means you need to be especially careful when you are cleaning up the surface of the head. “If you use anything on a drill or die-grinder, or even a Scotchbrite pad, you can dig into the aluminum and create sealing problems,” reveals Huneycutt.
“I spray on some gasket remover, let it sit for about 10 minutes, then carefully use a carbide scraper to CAREFULLY scrape away the head gasket material. You can get away with a razor blade here, but the carbide scraper won’t gouge the aluminum as easily. Follow that up with shop rags, lacquer thinner, and elbow grease.” Getting this step wrong can spell headaches down the road when trying to get the new head gasket to hold.
Cleaning The Valves
Assuming all of your valves are straight and free from damage, reusing them in your budget built is a no-brainer. “If you have a bead blaster, you can clean them up that way, but this is low buck, so we’re going to clean the valves the low-buck way,” explains Huneycutt.
“Wrap the valve stem in painters tape to protect it, and chuck it up in the drill. This may seem irresponsible, and you do have to be really careful. Just snug it up in the chuck, spray the valve with a lubricating oil, and spin it against a Scotchbrite pad, just to get the rust and junk off of it. You don’t want to be too aggressive and try and shine it up like new, just enough to knock the junk off of it.”
Lapping The Valves
Whether you had leaks or not when you checked your valves, lapping the valves is cheap, easy, and only requires a minor amount of effort, making it a no-brainer step. “You might as well do it to get the best possible seat-to-valve seal as you can,” Huneycutt says.
“Simply apply some lapping compound around the seat area of the valve, and drop the valve into place” Using a valve lapping stick, you simply spin the valve back and forth in the seat, while applying light pressure, like you are starting a campfire the old fashioned way. “You’ll hear it when it smooths out,” says Huneycutt. “Lapping just helps clean up the entire seat surface for the best combustion chamber seal possible.”
Simply the reverse of taking everything apart, this is where the attention to detail really comes into play, as hopefully you’ve kept everything that has come off the head in its proper spot. “Because the parts all came off of a used engine, it’s important to make sure they all stay in the same spots they came off of.” Huneycutt explains.
“They have all worn in with each other. Just like a cam and lifters, keeping all the mated parts together is just a good idea.” Remember to lube up the valve stems and putting everything back together should be easy. “Once everything is reassembled, we give each head of the valves a pop with the mallet to make sure everything is seated and away you go!”