cmerc
Junior Dragster
Posts: 5
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Post by cmerc on Nov 4, 2005 7:43:02 GMT -5
Ah, the price we pay in Aggravation, Time and Money to keep these Cars going!
Changed injectors, reworked tune, now I suspect I have bad Valve Seals. What's the best way you guys have found to change seals without removing the heads. (AFR heads '94 Z28 LT1.)
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Post by Fire67 on Nov 4, 2005 11:32:57 GMT -5
Use an Air hold valve (threads into spark plug hole to pressurize cylinder w/compressed air) to hold the valves up. Then just remove the locks, ret., springs, and valve seals.
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Post by the94z on Nov 4, 2005 15:45:08 GMT -5
god we need one of those FAQs for this so badly! With pics of the steps!
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Post by DocSpeed on Nov 4, 2005 17:39:34 GMT -5
Use an Air hold valve (threads into spark plug hole to pressurize cylinder w/compressed air) to hold the valves up. Then just remove the locks, ret., springs, and valve seals. This tool is worth every penny, keeps you from having to remove the heads to install the new valve seals.  |
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Post by the94z on Nov 6, 2005 13:27:10 GMT -5
it sounds harder than typed.....Im a newb and have never even seen one of these machines....but I suppose I should:
1. Borrow from Advanced auto parts
2. remove Sparkplugs on one side of the engine....or is it just one at a time?
3. Screw machine in.
4. Remove valve cover.
5. Turn machine on,
6. Go up top to valve cover and....then what am I looking at?
Im stuck there....
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Post by DocSpeed on Nov 6, 2005 21:12:35 GMT -5
It is just an tool that fits on the end of an air hose connected to an air compressor. The air pressure keeps the valves up and from falling while your changine the seals. You will just remove one spark plug at a time. You will need a valve spring compressor to get the springs to compress so you can remove the locks and retainers. Again you will remove the exhaust and intake springs for the cylinder that you have the hose plugged into. I hope this answers your question, if not, just post again.  |
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Post by the94z on Nov 7, 2005 1:30:23 GMT -5
exhaust and intake springs....uh...a pic of these things would be helpful just to know what they are for those that have never been in there....and btw if taking off my intake manifold...could i do it from there or I would still have to go through the valve cover...?
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Post by Alex94TAGT on Nov 12, 2005 3:22:07 GMT -5
Honestly, I don't know why anyone would want to mess with the 'compressed air' method. Sure, it works, but it's hard enough just changing spark plugs -- let alone screwing in a fitting and connecting an air compressor hose.
Personally, I prefer the "top dead center" method. Find #1 TDC, then you can go ahead and remove both the intake/exhaust valvesprings for cyl 1. The valves will rest on the piston as you work. When you're done reinstalling those valvesprings and resetting the valve lash, give the crank a quarter turn, and go to the next cylinder in the firing order. The entire process will take two rotations of the crank, in 1/4-turn incriments.
This is oversimplified, but just getting the general idea out there. It's far easier to find TDC than it is to attach an air hose to the cylinder head.
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Post by 1bad2k2ta on Nov 12, 2005 8:44:03 GMT -5
Honestly, I don't know why anyone would want to mess with the 'compressed air' method. Sure, it works, but it's hard enough just changing spark plugs -- let alone screwing in a fitting and connecting an air compressor hose. Personally, I prefer the "top dead center" method. Find #1 TDC, then you can go ahead and remove both the intake/exhaust valvesprings for cyl 1. The valves will rest on the piston as you work. When you're done reinstalling those valvesprings and resetting the valve lash, give the crank a quarter turn, and go to the next cylinder in the firing order. The entire process will take two rotations of the crank, in 1/4-turn incriments. This is oversimplified, but just getting the general idea out there. It's far easier to find TDC than it is to attach an air hose to the cylinder head. Excellent point, Alex. Plus, you don't have to have access to a compressor, or buy and additional hardware. Thanks! |
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Post by the94z on Nov 12, 2005 15:22:50 GMT -5
ya but thats just very confusing never messed with top dead cneter or crank, or anything like that, I was quoted 185 to change both sides of valve seals....this is with stock headers, he doesnt know if he will have problems with my hooker midlenght 2.5 inch....do yall think he will? And also he told me that if my guides are bad he has to remove the heads....sucks...yall think they will be?
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Post by Alex94TAGT on Nov 12, 2005 22:09:41 GMT -5
ya but thats just very confusing never messed with top dead cneter or crank, or anything like that, I was quoted 185 to change both sides of valve seals....this is with stock headers, he doesnt know if he will have problems with my hooker midlenght 2.5 inch....do yall think he will? And also he told me that if my guides are bad he has to remove the heads....sucks...yall think they will be? Well, regardless of whether you WANT to find top dead center, it is REQUIRED for setting the initial valve lash adjustment after removing the rocker arms. Either way, you have to do it. Using the method I suggested, you're merely killing two birds with one stone. It really isn't all that difficult, once you get familiar with the process. exhaust and intake springs....uh...a pic of these things would be helpful just to know what they are for those that have never been in there....and btw if taking off my intake manifold...could i do it from there or I would still have to go through the valve cover...? Sorry, I didn't see this earlier. First off, removing the intake manifold will NOT gain you access to the valvesprings. The valvesprings are located underneath the valvecovers. The valvecovers are bolted to the top of the cylinder head. There are 16 valvesprings in total. We have two valves per cylinder, and eight cylinders. Thus, each cylinder head will have 8 valvesprings. I uploaded some photos of my cylinder heads to explain what's what. They are a little sloppy, but it should get the point across: Bottom of Cylinder HeadTop of Cylinder HeadOf course, if you're having a shop perform the work, then this information is a little pointless... |
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Post by the94z on Nov 13, 2005 2:35:34 GMT -5
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cmerc
Junior Dragster
Posts: 5
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Post by cmerc on Nov 13, 2005 14:29:31 GMT -5
So, with the piston at TDC, how far does the valve drop before it hits the top of the piston? I understand the theory of this, but as I have never done it this way, I just am not sure in my mind that you will be able to replace the valve spring retainer locks unless the valve is all the way up (SEATED).  ?? |
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Post by Alex94TAGT on Nov 14, 2005 17:26:37 GMT -5
So, with the piston at TDC, how far does the valve drop before it hits the top of the piston? I understand the theory of this, but as I have never done it this way, I just am not sure in my mind that you will be able to replace the valve spring retainer locks unless the valve is all the way up (SEATED). ?? I did this over 3 years ago with my first cam swap, so I know it is 100% possible. After you've removed the valvespring, the valve can only drop about a 1/2" tops. During removal, when you have the valvespring compressed with a screw type compressor, you can simply pull the valve to it's topmost position, and then put a little side-pressure on the valve as you push down. This will pop the locks loose from the retainer, and you can then use a small magnet to remove them. For installation of the new valvespring, the friction of the new valvestem seal, along with the tight tolerances of the valve guide, will keep the valve stuck in the 'up' position as you carefully position the compressed valvespring over it. Drop in the locks, and you're set. I was actually going out into the garage to measure my old valves, because I'm not 100% certain that it's physically possible to "drop a valve" into the cylinder. Even with the piston at BDC, we only have a 3.48" stroke. I believe the top of the valvestem will still be in the valveguide at that point, in which, you could just rotate the crank to bring the valve back up beyond the guide. Don't quote me on this though -- it's still VITALLY important that you find #1 TDC (not #6) and follow the firing order precisely. We can go into finding TDC if you wish. |
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cmerc
Junior Dragster
Posts: 5
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Post by cmerc on Nov 14, 2005 19:42:14 GMT -5
Thanks for the well detailed procedure, I can see it all in my mind's eye. Thanks but no need to go into finding TDC.
Thanks all for the info.
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