UKKid35

I have a pair of used heads which I intend to use for my repair. I would like any tips you can give me on replacing the valve seals. Also I want to take all the valves out in one go to clean them, is there any safe way to mark them so they go back where they came from?

Thanks

stuartph

Paul


Hi mate its stuart with the GT in kent.

If you gonna take the valves out of the heads, what i have done before is get some cardboard mark it up like the head and punch the valves into the card, and put each valve spring and collets and lifter in a freezer bag like you get from tescos. its alot of bags but it does work.


stuart

GT

tresamore

Hi Paul,
I recently did all that you are going to do. Get a valve seal installation tool in hand before you begin. I had a very hard time finding one here and luckily a fellow Rennlister was able to lend me one so I didn't have to wait 3-4wks to get one from Germany. I would think you'd have better luck finding one in the UK. Some people will tell you to use a 1/4" socket but its not worth the potential nightmare of a seal coming off later or being crushed during assy. I wouldn't clean all the valves at once. I did what Stuart is suggesting and made a template. There are shims under the springs and you want to keep all your parts per valve in one place. You don't want the valves banging into each other and leaving dents or scratches during cleaning either. Choose your spring compressor carefully if you can't get hold of a factory tool. I was able to modify a unit from a local parts store and it worked fine (can't remember the manuf). Be careful you don't score the lifter bores. I cut a piece of plastic from an aerosol can cap to line the bore as an extra precaution while removing the retainers and locks. A small, strong telescoping magnet is a must to get the locks out. A good way to secure the head to the workbench helps a lot also. I placed a rag under the head in the dome to hold the valves up while compressing the springs. If you don't, the valves will slide down when you compress the springs. They'll only go down a bit until they hit the bench, but that just means more work to compress the springs further to get the locks out. The old seals are going to be harder to remove than you think and they're tricky to access with all of the head castings in the way. I ended up using 10" 90° needle nose pliers w/ some small plastic pieces I found at work covering the jaws to protect the top of the guide where the seal mounts. It was a bear to remove all 32, but be patient. I have a parts washer w/ the same solvent most mechanics use and it didn't clean the parts at all. I ended up buying a gallon can of carburetor cleaner and it worked incredibly! I slid all the parts onto the valve stem and soaked each valve + parts for about 20 minutes and they looked like new. My local machine shop said the valves and seats looked great and that I didn't have to recut them. They also said that the guides measured well within spec. A quick hand lapping was all I did. Having a set of repair manuals by your side during all this is a must also. You can't always afford to buy the factory tools or be able to do things the same way, but there are plenty of ways to improvise as long as your realistic about it. Any question let me know.
Have Fun,
Randy

UKKid35

Hi Stuart, I now have 32 more ziplocs with labels printed.

Thanks Randy, that was exactly the sort of warning I needed. I've just bought the spring compressor, it's the G clamp type specifically for deep set multivalve heads, so I won't have the problem of the valve dropping through. I can ask my dad to help make a seal installation tool, he's very good with a lathe, as long as I can show him what I need. I will get some carburetor cleaner as you suggest, I've got loads of other parts to clean too!

Thanks again for the advice.

Kevin in Atlanta

I've done this a couple of times on 32 and 16 valve heads. As long as you are doing all that, might as well buy some valve lapping compound and lap the valves. Lapping tools should be inexpensive. Just be very sure you clean ALL the lapping compound off the heads when you are done. BrakeClean is what we used.

If you buy, rent or borrow a pair of stands for elevating the heads off the workbench, the job of removing and installing the valves goes much quicker.

UKKid35

Thanks Ti, I was intending to lap the valves, as you point out it will add very little to my costs. I don't have a workbench as such, I was going to try to use a Black and Decker Workmate to hold the head as I'm working on it. I'm extremely limited for space, I'll eventually post a pic of what a 928 buddy described as a "nest" in my hallway which is the only place I can work.

tresamore

Paul, I did a quickie reverse engineering print of the seal install tool. I'll try to scan it and send it to ya.

Randy

UKKid35

That would be brilliant!! Thanks

tresamore

I threw this together as quick as I could w/o the boss catching me. The drawing was too confusing. Let me know if I missed anything.

Fastest928

dont forget the valve condoms..........

Marc
DEVEK

tresamore

True true Marc,
They only give you 1 so be careful. If you rip it, you may end up with a 48 valve motor in 9 months. Do the math on that one and see if you can figure it out.

jon928se

Am I missing something? Do you need a tool to insert the stem seal because it is too far down the "hole" to push it on with fingers (My normal method) or is it too difficult to push on with fingers ?

Jon
Engine rebuild coming up after xmas.

UKKid35

I owe you Randy, thanks a million! I'm going to have to pop down the Family Planning Clinic too, they give out Valve Jackets for free in this country...

tresamore

Jon,
If you push them too far it can begin to open up the seal larger than the valve stem diameter and you risk damaging it. Too little and you risk it falling off. Plus they require a little effort to get them on. I tried it w/o the tool and ended up ruining 2 seals. After I got the tool I could see why porsche made it. You need the valve condom to slip over the tip of the valve so you can slide the seal on. Oh yes, Paul, put the valves in first then the seals. I'd hate to see you do 32 seals and then realize you didn't have the valves in.

UKKid35

Ah, I got the wrong end of the stick, as it were. I thought the condoms were a suggestion for protecting the valves while out of the cylinder head. Thanks again, your help has been invaluable.