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Tuning Junkie
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151 Posts
Discussion Starter #1
Hello everyone,

Is it normal for air pressure to leak down through the rings some while pressure is put to the cylinder to hold the valves up and change springs. I can hear it hissing out and i'm not sure if it will hold the valves up while its leaking a little like that ?

None of my cylinder hold air perfectly ? Would it help to change valves to squirt oil in the cylinder to help hold pressure in around the rings. ?? Or does my engine just sound beat. I dont remember any air leaking at all on the last one i did but that was years ago on a push rod motor. It ran great, no problems at all, smooth running. I attached a pic of the plug form #5 . Its the only one like that.

Thanks for your thoughts.
 

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King Trashmouth
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21,891 Posts
All engines will have some degree of leakdown. How much depends on your ringpack/cylinder, how it's designed and how worn it is. You can verify how worn it is using a leakdown tester that will give you a value.

Oil might help them if they're a little worn. But as long as there's enough air flowing in to maintain pressure, it will hold the valves. Think of it like a balloon. Even if it has a leak, as long as you're blowing in it enough it will stay inflated.

That said, if you're really worried, you can keep valves from dropping using the rope trick. Bring the piston to near BDC, and feed in as much rope as you can from the spark plug hole. Turn the engine until you feel resistance from the rope bunching up, and that rope will keep the valves in place.

That plug looks like it has a lot of ash deposits, likely from oil.
 

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Tuning Junkie
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151 Posts
Discussion Starter #3
my oil system is empty so maybe that is causing excess leak down .

Have any of you had luck using OEM brand valve spring compressor # 24434.

https://www.amazon.com/gp/product/B...beb-4819111bef9a&pf_rd_r=59J0XRP8GA16XG45W7ET

I Need to find a new valve spring compressor the reviews are kinda mixed for the one above. wondered if anyone has used it. the price is right. I almost tried bolting my balancer puller to the cam caps and push the spring down like that but i think im asking for trouble that way.

Sorry guys but most of my experience and tools are from push rod engine work. Its a new surprise all the time with the modular engine, haaaa, thats what makes it fun I guess.

Ive been looking for the big universal valve spring compressor that bolts on the head but I cant find anyone to rent it. Im really trying not to be cheap but this project is just getting bigger and I have to watch the budget.

I may use the rope trick, seems more fail safe. Thanks WickedSnake00
 
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