1992 LT1 Rocker Question:
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Race Director
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Another question:
I plan to do the Crane Gold Rollers, and valve springs. I plan to use LT4 springs. Both of these jobs will be a first for me. Anyone have a suggestion on the method for the spring replacement?
I plan to do the Crane Gold Rollers, and valve springs. I plan to use LT4 springs. Both of these jobs will be a first for me. Anyone have a suggestion on the method for the spring replacement?
Race Director
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Originally Posted by Craig Brumley
Anyone have a suggestion on the method for the spring replacement?
Actually it's not THAT bad a job but you will need to remove your spark plugs so if you haven't done plugs and wires in a while it would be a real good time to consider them as well. There are several different ways but I prefer the "air hold" method. In this manner you remove a spark plug and thread in a special adapter that you connect to your air compressor. Note, this means a good REAL air compressor, not a 12v powered tankless variety for inflating tires. When the cylinder is pressurized this will hold the valves closed so that you can compress the valve spring and remove it without fear of dropping the valve. Then, working quickly because you don't trust your air compressor 100%, you can put the new spring on. You don't have to go at hyper speed but the shorter period of time that you go with the spring off, the less time there is for something to go wrong. The last thing you want to do is drop a valve and have to pull the head to retrieve it.
I can write you some much more detailed instructions if you like but this should give you some idea of what you're looking at.
Team Owner
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From: I'm the walkin dude I can see all of the world...
St. Jude Donor '03
You can get the "special adaptor" Nathan is talking about in most compression test kits. It will be a hose with an air fitting on one side and a spark plug size thread on the other.
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Race Director
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From: Lake Wylie SC
What kind of air preasure do you need to hold the valves in place? Mine, the compressor, usually holds about 100 psi. Won't that push the piston down? I haven't done this with the heads on the engine. Always learning something.
I think I figured it out, just keep it in gear with chocks in place.
I think I figured it out, just keep it in gear with chocks in place.
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Sure, but who cares if it pushes the piston down because the air pressure holds the valves up. Leave it in neutral and let it spin the engine all day long. Granted you don't have the safety net of the valve hitting the piston if it falls but you don't have time consumption and the annoyance of trying to find TDC for every cylinder.
Nearly any air compressor will work provided that it can maintain that pressure, 100 PSI is fine. Really all you need is something that can keep up with the leakage in the cylinder which will just be around the rings. With a decent compressor it will run every few minutes just to maintain pressure. If your comrpessor has to try and run constantly you'll probably burn it up.
Nearly any air compressor will work provided that it can maintain that pressure, 100 PSI is fine. Really all you need is something that can keep up with the leakage in the cylinder which will just be around the rings. With a decent compressor it will run every few minutes just to maintain pressure. If your comrpessor has to try and run constantly you'll probably burn it up.
Safety Car
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From: Southwest Kansas
2022 Corvette of the Year Finalist -- Unmodified
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I am considering this mod myself, and like strick I have only done this with the heads off using a valve spring compressing tool (big C clamp looking tool), how do you get the spring compressed enough to take the keepers out and then compressed again enough to get the new springs and keepers back on? Sorry to be such an idiot, but I just can't fathom how this will work. (I understand the air compressor holding the valve in place, just not the tool used to compress the spring).
Le Mans Master
Joined: Apr 2000
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From: Manassas VA
You buy a tool designed to compress the the spring with the heads installed on the car. They make a few different styles. One style bolts to the stud and you leverage the handle which has a fork that compresses the spring. Then I use a magnet to remove the keepers. On reinstallation, I put a dab of axle grease on the keepers to hold them in place until the spring is released to hold them. By the way, while replacing the springs take the time to install new valve seals. they are easy to do and cheap.
Melting Slicks
Joined: Nov 2004
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From: Cape Coral FL
Originally Posted by VictorRussell'92
You can get the "special adaptor" Nathan is talking about in most compression test kits. It will be a hose with an air fitting on one side and a spark plug size thread on the other.
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This is interesting. I had not heard of the compressed air thing. I thought the spring removal tool would be enough to keep the valve in place, but it sounds like a good extra step to help avoiding the disaster of dropping the valve into the cylinder.
I am curious as to why you wouldn't want to leave the vehicle in gear to prevent the engine from turning over; seems to me that would not be good for bearings, etc.
What is the method to remove the valve seals?
I am curious as to why you wouldn't want to leave the vehicle in gear to prevent the engine from turning over; seems to me that would not be good for bearings, etc.
What is the method to remove the valve seals?
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If you look carefully at how the springs are attached to the valve you'll see that there is no way for the valve to stay in place if you compress the spring unless something is physically holding the valve up from the bottom side.
Team Owner
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St. Jude Donor '03
Or you can just do the air in the spark plugs one at a time for each valve. The other 7 spark plugs will keep the engine from spinning over just fine.
Last edited by VR'92; Jan 11, 2006 at 10:26 AM.
Race Director
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Maybe. I can turn my engine over by hand with all the rockers removed and all the spark plugs in place. Granted it's a royal PITA but the compressed air may be able to move it if the pressure is high enough.
Team Owner
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From: I'm the walkin dude I can see all of the world...
St. Jude Donor '03
I did not shim mine (LT-1 to LT4) during my install but I think others have.
Although I learned it is pretty important to go ahead and replace your old roller lifters and pushrods even if they look great. (My roller lifters had some weak return springs which made rocker adjustments a serious headache)
Although I learned it is pretty important to go ahead and replace your old roller lifters and pushrods even if they look great. (My roller lifters had some weak return springs which made rocker adjustments a serious headache)