Looking to change valve springs and upgrade to roller rockers. I need the adaptor to port compressed air into the spark plug hole to keep the valves closed. I did a search and didn't find anything the appeared to work. Ideas?
Spark plug air input adaptor?
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No need for that. Just turn the crankshaft bolt with a big wrench till the piston is on its intake stroke until it is near bottom dead center. Insert a softish suitable rope into spark plug hole, turn crankshaft again to bring up the piston. Stop when the piston no longer wants to move and rope is compressed into the combustion chamber.
You need a Lisle 19700. Get it from Amazon.
If your plugs are down a tube, use a long length of rod in the hose to keep it straight. Cut the rod long enough so that it rests on the piston at BDC.
https://www.lislecorp.com/specialty-tools/valve-holder
If your plugs are down a tube, use a long length of rod in the hose to keep it straight. Cut the rod long enough so that it rests on the piston at BDC.
https://www.lislecorp.com/specialty-tools/valve-holder
no...just no
I bought my air adapter off the shelf at NAPA.
on order...thank you!
Before you start taking things apart inspect the valve keepers and retainers. If they look worn or anything other than perfect order a new set. Probably a good idea anyway if you are getting stiffer springs.
Thats what i have done. less chance of dropping a valve. Easy.
Not sticking anything that most likely has contamination into my engine.
+1 I use this same adapter.
Start with fresh rope if you want; works fine and is fast and easy
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Absolutely and has been done this way since time immemorial. I trust the actual physical support more than compressed air (which has a number of potential fail points).
Just a follow up regarding plugs in tubes...
Once you have the hose threaded into the spark plug hole, pull the rod out.
Please correct me if I am wrong, but if the piston is around TDC on compression, then the valves won't fall that far if the air does fail. I can re-apply air, grab the stem, and pull it back closed...right? Also I get an idea of how well the valves and rings are sealing...
I'm not sticking a rope in my engine...
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Maybe. And sure, all that metal-on-metal insude, and a soft piece of rope with the end hanging out of a plug hole scares you? Lol
You don't crank it around with the rope in there. At most, move the crank a few degrees just to snug it in. And the end hangs out the plug hole. Rope doesn't get inserted til you're almost at TDC. I'm struggling to understand what your staunch opposition to the idea is.
That said, either method is fine. Whatever works best for you, brother!
I do the rope trick on chainsaws all the time. Not for valve springs of course, clutch or flywheel nut removal.
