pressure testing 49/53 block

[offy19]

How much pressure can the block safely stand, and will this test find a crack if any? I'm using the Speedway motors block plate. Thanks for your help.

[uncle max]

Pump to 20 lbs and leave it overnight.

[Karl Wolf]

Figure what the cyl takes on a combustion cycle...
I made a pressure test plate for myself, I find that it can hold 80 lb... I like to use a lot but I think that 30 lb is enough to spot any problem... In a machine shop using an Irontite bench, that was as good as I could do... Presure test will find a leak, not all cracks leak... Magnaflux will find cracks- but won't tell you if there is a leak. Both have their place... Karl
Oh, yeah, when you pressure test, use soap in water without a lot of suds, and look for bubbles... Even a tiny leak should be possible to find, especially look behind where the valve springs are- and, well, all over...

[Ronnie]

30 to 40 lbs is where shops test at. Set it up in a closed loop situation and any leaks will be apparent in 1/2 hour or so due to pressure drop .. If leaks occur pressure up again and mix up a soap and water solution and inspect for leakage very simple and easy to do.Will give you a good inspection results. Hope this helps.

info https://www.youtube.com/watch?v=Tsc1P9WhIuU

Ronnie

[jdl]

Pressurize to 30lbs. then use wd40 in a hand pump sprayer (not spray can). squirt the wd40 all around the valve pockets, cyl. walls, and every place. if there is a leak you will see it. take your time doing this. you can also have it magnafluxed. I have found leaks after having the machine shop magnaflux the block and telling me the block was good. not so.

[36tbird]

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I am about to do this test on a 59A short block. I am trying to avoid a complete rebuild at this stage so the studs are still installed. I have the Speedway kit and will modify it by cutting short pieces of pipe/tubing to fit over the shanks of the studs to tighten the plate down. My question is this, I've heard of some soluble ceramic coatings or something, maybe old Barrs, that might seal up a minor crack. Anybody tried anything like this? Is there such a thing as a minor crack? Just asking in advance of possibly discovering some problems.

[jdl]

K&W engine block sealer or Cargo block sealer...follow directions exactly.

[Karl Wolf]

Instead of cutting spacers, I stack 1/2" or 9/16" nuts, easier... Karl

[BOSSY]

I had a flathead motor stitched and ed tested it with 40 lbs. of air.

[52merc]

Originally Posted by offy19

How much pressure can the block safely stand, and will this test find a crack if any? I'm using the Speedway motors block plate. Thanks for your help.

offy how much for the plates from speedway thanks

[offy19]

Hello 52', the catalog part# 560-82260 lists at $254.99, includes a pressure regulator

[Mike B]

Some good info here in this thread, In worked for a shop (many years ago) that used plate over the combustion chambers (OHV, notb flatt heads) and with the valves in and sitting, no spring tension, they'd run the pressure upwards of 300 PSI, all along the time with a stethascope with one of those airnozzle things, to "hear" how much would/was leaking past the valves...is i possible to do the same on a FH?

[offy19]

Too many sq inches of area inside a flathead water jacket for that kind of pressure! (in my opinion) 30 to 40# sounds reasonable

[Ronnie]

Just a comment what shop would have "300 psi" available out on the shop floor.Pretty stout compressor.That's more than double the norm.

Not to many I have been but then again maybe but don't think so.What a tough airline would be required for that set up.I've also never seen the procedure talked about. You wouldn't catch me with stethoscope listening for a leak at 300 psi. The procedure sounds more for a conventional leak test done on ohv. heads but they are assembled and use vacuum to test valve seat seal not pressure but perhaps in some shop somewhere all I can say is haven't run across that one yet. Quickly looking at the test the untrained eye may think it was a pressure test.
Has any one else seen this?

[Cecil/WV]

Originally Posted by Ronnie

30 to 40 lbs is where shops test at. Set it up in a closed loop situation and any leaks will be apparent in 1/2 hour or so due to pressure drop .. If leaks occur pressure up again and mix up a soap and water solution and inspect for leakage very simple and easy to do.Will give you a good inspection results. Hope this helps.

info https://www.youtube.com/watch?v=Tsc1P9WhIuU

Ronnie

So, when my block held pressure @ 100 lbs, it would probably be okay.

[36tbird]

yes, bragger.

Hey, Karl, thanks, that is a great idea. Lou