Ok, I know how to change them once I get to the point to where I can change them. What I need to know is how do I get the cylinder ready to fill with air, or is there another way to do it? I am in the middle of my cam swap, spring change, rocker change. all of the front of the motor is off, the timing chain/spockets are off, new cam in, rockers off, pushrods out. If everything was hooked back I think it would be easier.

I dont now how to get the cylinder at TDC, when I turn the crank clockwise while having my finger covering the spark plug hole I can feel air being sucked in and then pushed out, at what point is that cylinder at TDC? once I get it at TDC I can just take the valves off without having to fill with air?


Im lost guys, help me out here! thanks

 

When your finger stops feling air being pushed out the hole, thats TDC...but you cant just let the valve drop because there is still to much of a gap between the piston to valve. It will fall down to much, and the spring will coil bind, and you still wont be able to get the keepers on.

You have to use a fitting, like off a compression gauge, that threads into the plug hole, that you can then hook upto you aircompressor. Or you can take a nylon string/rope and feed it into the cylinder, the rotate upto TDC or as close as you can get it, so that the rope fills in the area so that the valve wont drop.

 

You'd first set your engine in #1 cylinders tdc, you will have a mark on your damper that should allign but you have to make sure both springs are up, if not you have it on #6 and you have to go another turn. Most autopart stores sell a little hose that will fit into the sparkplug hole so you can keep the valves up with airpressure from a compressor while you are changing the springs. You do need this otherwise the valves will drop down and you wont be able to put the new springs on ( you still can but it involves bending a coathanger to keep the valve up, much harder). The firing order for a chevy V8 is 1-8-4-3-6-5-7-2. When you are done with the first set of springs you have to turn the damper until you see both springs on the #8 cylinder and replace those, keep going like that and use the fireing order to determine which one you have to change next. It takes 1/4 turn for the next cylinder to be in tdc. If you take the distributor cap off the rotor should spin clockwise. The driver side front cyl is 1 and goes back 3, 5, 7. Pass side front is 2 and goes back 4, 6, 8. Thats should cover all the info you need,

Peter

 

If your intake is off, I'd take the heads off and check them out. Maybe lap the valves. In any case, It would be good to look down the cylinder bores and check the valve guides with the head off and pressure test it. I did heads, cam and lifters once but soon after, the engine was smoking. Shoulda checked compression and leakdown before I did it. Live and learn.