Valve spring swapping
#1
Instructor
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Valve spring swapping
Has anyone changed their valve springs? I am trying to change mine but can not get the valves to stay up. I have tried running between 20 and 80 psi into the cylinder to hold them up but they don't stay up when I compress the spring. Has anyone had this problem? Am I forgeting to do something?
#2
Re: Valve spring swapping (AV76)
Bad rings or valve guides? Does it do it on every cylinder? Your at the bottom of the piston stroke so neither valve is cracked open? Only suggestions I have.
#3
Heel & Toe
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Re: Valve spring swapping (AV76)
I do not know if this is the problem but sometimes the keepers get stuck in the retainers. The way I normally deal with this problem is to get a deep socket that just fits over the retainer and give a couple of gentle raps then try the spring compressor to see if they loosened. If not try the deep socket routine again using a liitle more force. I'm assuming you are able to hold air pressure in the cylinder.
#4
Melting Slicks
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Re: Valve spring swapping (AV76)
I don't mean to give you the idiot treatment, but are you pulling the spring from the appropriate cylinder when it is at top dead center? If you aren't the air is rushing out the intake or exhaust valves and no amount of air in the cylinder will hold the valves closed. I just did this not too long ago and it wasn't that difficult for a first timer.
Gary
Gary
#5
Le Mans Master
Re: Valve spring swapping (AV76)
Definately just give the valve a whack with a mallet. The socket idea is good too. Once the keep is unfrozen, you're home free.
I bought the cheap angle iron type compressor from Sears for around $10-12 bucks. It worked much better than a special $50 compressor from Summit. I bent the angle to almost 90 degrees so it fit around the carb and it made life simple.
Good luck
I bought the cheap angle iron type compressor from Sears for around $10-12 bucks. It worked much better than a special $50 compressor from Summit. I bent the angle to almost 90 degrees so it fit around the carb and it made life simple.
Good luck
#6
Burning Brakes
Re: Valve spring swapping (GaryS)
Gary - I wouldn't even bother bringing the cylinders to top dead center. There's really no reason to do this since you have to take the rockers off anyhow. Once you take the rockers off, the valves are brought all the way up to the seat by the spring. It's a needless step if you're using air pressure to hold the valves. If you don't want to use air pressure, I THINK you can bring each cylinder to top dead center and the valves will hit the piston with enough stem left to pull them back up. I wouldn't be brave enough to try it though.
-dath
-dath
#7
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Cruise-In VI Veteran
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Re: Valve spring swapping (AV76)
Another method of holding the valves up is to take a couple of feet of soft nylon rope("1/4-"1/3 diameter) and feed it into the head through the spark plug hole. Then you can take the valve springs off with out worrying if you are going to drop a valve into the cylinder. Make sure you have each cylinder near TDC, then you won't have to feed in so much of the rope (it gets to be a real PITA after a while.)