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FE Power Forums => Private Classifieds => Topic started by: dozz302 on October 28, 2025, 03:07:46 PM

Title: What preassure to test heads and block to for "Preassure Test"
Post by: dozz302 on October 28, 2025, 03:07:46 PM

I was thinking 100 PSI would be sufficient but what is machine shop standard?

Title: Re: What preassure to test heads and block to for "Preassure Test"
Post by: 428kidd on October 29, 2025, 07:11:15 AM

Most seem to use double the normal cap pressure. I use 40psi  at home. I think 100 psi would be way to much.

Title: Re: What preassure to test heads and block to for "Preassure Test"
Post by: My427stang on October 29, 2025, 09:52:34 AM

I generally do 40 psi if I am doing one with freeze plugs.  However, I have run it up to line pressure on a couple of Genesis blocks. 

FWIW, I do mine with a torque plate and a water pump fitting, one side at a time.  I say that because mine is not a pressure tester, which generally use clamps and rubber gaskets with plexiglass or alum plates, so those certainly run lower.

I'll tell you, at 40 they bubble very clearly with soap spray.

Title: Re: What preassure to test heads and block to for "Preassure Test"
Post by: pbf777 on October 29, 2025, 11:13:17 AM

       Yes, 35-45 p.s.i. is about as high as most shops will go. 

       First, as mentioned, the typical "pressure-tester" set-up and particularly the manor in which the exposed passages are blocked won't generally hold beyond such, if even. 

       Next, be careful (always) if running the pressure to higher numbers, as when you consider "area times pressure" there can be a significant sum of force being retained!  Can you picture a "core/cup-plug" coming dislodged from the side of the block and the potential velocity it might possess?   :o

       Scott.

Title: Re: What preassure to test heads and block to for "Preassure Test"
Post by: galaxiex on October 29, 2025, 07:43:19 PM

Pneumatic pressure can be extremely dangerous.

Google search "pressure testing steam engine boilers", to see how they do it safely.

They never pressure test with air, only liquid.
That may not be practical for testing an engine block.


Here's one example of pressure testing a boiler for a model steam engine.


https://www.youtube.com/watch?v=xpJLL4q2J9g