When should valves be replaced?
When should valves be replaced?
If you’re tearing down a race engine, therefore, some clues to look for that would indicate it’s time to replace the valves would be loss of valve lash (due to valve stretch), unusual or uneven seat wear, scuffing on the valve stems, or wear or chatter marks in the keeper grooves.
How long does it take to replace a valve seal?
This can, of course, be very time consuming, and it can take a lot of hours to replace the valve seals. If you can do the job by yourself, you can do it cheaply because the cost of the valve seals is pretty cheap – it is the time to replace them that costs.
When do you know it’s time to replace a valve?
If you’re tearing down a race engine, therefore, some clues to look for that would indicate it’s time to replace the valves would be loss of valve lash (due to valve stretch), unusual or uneven seat wear, scuffing on the valve stems, or wear or chatter marks in the keeper grooves.
How often do exhaust valves need to be replaced?
An exhaust valve that may last for years and up to 150,000 miles or more in a typical passenger car engine might only last a season or two in a dirt track or drag racing engine. A set of titanium valves in a NASCAR motor might be replaced after a single race.
How often should Valve be replaced in NASCAR?
A set of titanium valves in a NASCAR motor might be replaced after a single race. In a Top Fuel dragster, the valves might be replaced every six to eight runs.
When does a valve job need to be replaced?
Once the head passes this point, it is also checked for flatness. The surface of the head must be flat to seal the head gasket against the block. Excessive warpage, roughness or any damage can cause the head gasket to fail. If the head exceeds the maximum allowable out-of-flatness specs, it must be resurfaced or replaced.
Can a cast iron valve head be replaced?
Most install new guides, guide liners or bore out the old guides to accept new valves with oversized stems. Aluminum heads have cast iron or bronze guides that can be replaced but most cast iron heads do not. If the valves are to be reused, they will be inspected, checked for straightness then refaced.
When do valve liners need to be replaced?
They’re almost always worn, so they either need to be replaced, relined or knurled (a process whereby grooves are cut into the inside diameter of the guides to decrease the bore size). Few shops knurl guides anymore. Most install new guides, guide liners or bore out the old guides to accept new valves with oversized stems.
When do valve springs need to be replaced?
If a seat is cracked or too badly worn to be refaced, the seat must be replaced. If that isn’t possible, then the entire head must be replaced. The valve springs are all inspected and tested to make sure they are still capable of maintaining proper pressure. The spring retainers, keepers and other hardware is likewise inspected.
