I picked up a later style ford flathead motor that was in running shape I had it boiled and magged and sonic checked at the machine shop everything checked out good another person I talked to recommended to pressure test it ? Im not familiar with flatheads at all is this necessary its gonna cost another $200 to pressure test any suggestions ?
A buddy of mine, Grumpy Ed on the board here, just went through the same thing. His didn't pass the pressure test, found some cracks, and it was a running engine.
Well, for about $40 books more than that you can get the blockoffs necessary to pressure test from Speedway! You probably already have a tire pump... The problem they address best after all the other tests is the possibility that you have a crack deep inside in the exhaust passages that go through water jackets, in areas entirely out of sight. No cracks so far, so most likely engine hasn't been frozen, but you never know. I have also heard of perforations allegedly from pooled water rusting through exhaust after years of sitting, again unlikely in an engine that doesn't have lots of visible damage from the same causes but worth worrying about.
Years ago I went to visit Al Sharp of Sharp Speed Equipment fame. He had just finished building a 3/8x3/8 296 ci Flathead for a '40 or '41 Ford pickup that he was building for himself. The block was machined out so far that it hit a pinhole in the casting which was probably caused by a rust pocket. The pinhole was not discovered until the engine was installed in the pickup and fired up. Al ended up buying another block and decided not to bore that one as big. He had to pay for another set of pistons and rings, another balance job, another valve job, porting and relieving, engine gasket set and more, not to mention all the work. You should pressure test the block when you first disassemble the engine before you spend one dollar on it and it would not be a bad idea to pressure test the block again after it has been machined, ported and relieved. I would buy a kit from Speedway for $254.00 and test it yourself. Its worth the money just to know you have a good block and it might just save you a lot of money in the long run. Once you go Flathead youll never go back. Your going to need this tool for future projects. It will get cheaper each time you use it. Nobody can build just one hot rod. its a sickness!
I now pressure test all blocks before I build them. I built one years ago that checked out just fine visually and mag test. However there was a crack in the upper part of the valve chamber that could not be seen. I had started to make my block off plates but never got around to finishing them until that happened. Luckily I found the problem on the test stand before installing it in the vehicle. $200 is cheap insurance if you can't do it yourself.
When I tore down my perfectly good, running flathead so I could freshen it up, I had it pressure tested and found out it was full of cracks. Money well spent.
And if the block checks out OK and you have the plates , you can fill er up with a boiling solution of water and water glass (sodium silicate) pressure her up overnight then drain for use on the other bank .This seals up any fine cracks or porosity that can lead to cracks and its permanent .
What about using the plates after you test and find a good block to put in the vinegar solution for a good clean out. Anyone done that? I was just thinking that would be another use of the plates and might convince me to buy a set.
Looks like you could make your own from an old stock head and some careful work on a piece of thick plate with a drill. Only need one water pump plate - tapped from both sides for the pipe fitting.
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