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I have a 94 thunderbird super coupe I pulled out the 3.8 supercharged engine. Put in a 302 I have been building on for a while. I had it magnifluxed, bored .40 over line bored all the goodies fully checked it all turned out good. i ported and polished my heads completely redone the valves lapped them had them magnifluxed(good). i put the 302 in the thunderbird fixed all the odds and end's pulleys,power steering, water pump etc. . and i used the sc radiator(downflow) small little thing. I left my thermostat out for break in purposes. blocked off the heater hoses on the water pump and the bypass. it ran good for about 10 minutes and then my front driver side freeze plug blew out so i put in a expansion plug in there and filled it back up and tried again it ran for about 15 minutes and boom another one the 3rd one on the drivers side. another expansion plug (just for now). It ran good for 30 minutes drove down the road fine started it back up ran for 10 minutes and found the middle one was GONE!! so i am at a complete hault any help or suggestions REALLY would be helpful and well appriciated. also some people said i need a crossflow that it could be building pressure with the downflow
 

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Yeah Just Guessin here , from what youve said . But Sound's Too me like your Leakin Compression intoo Water jacket System . Either Wrong Head Gasket ? Or Blown , Head Gasket ? Or Cracked head ? Run a CO2 Test on it . See if you have exhaust in Water System . Might try retorqueing Head's ? Carefull I once Peeled Topp off my Radiator when Head Gasket Blew . 120 PSI Leakin intoo a System that's Designed for 14 Too 22 PSI Max Do some funny thing's . Magna Fluxin is Good But it's Not Perfect ? Sean
 

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You BLOCKED OFF THE BYPASS HOSE PASSAGES?????? :nono: And the heater hoses...... Even though you have no thermostat, that is not a good thing to do. When you get a thermostat back in there, install the bypass hose, or else. But that is not your core plug problem.

Your radiator cap should relieve pressure at 16 psi. At about 40 the radiator will blow up. Unless there is a tremendous volume of escaping compression= doubtful. If there were that high pressure the radiator would be KAPUT. I have never seen a core plug just "blow out" even with blown head gaskets. Core plugs should stand way more than that (40) before they blow out.

I have heard too much of this happening lately.

I suggest that you have a bunch of poorly installed core plugs, :spank:

and maybe "import" made plugs that are too soft to hold pressure, :spank: :spank:

and I suggest pulling the engine and redoing every one of them, including the oil gallery plugs.

Your engine builder is the one responsible, take it back to him. If he refuses to redo them except "one at a time" then you know the quality of the person you are dealing with. (In most states he would be liable for multiple failures, towing, and engine damage if he fails to replace them.)
 

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Frozen...not

Wrong freeze plugs or made in ???? If you have ever beat the old ones out you will know how hard they are to install/remove. Your machine shop will have fun R&R ing them call 1800 tow my car to the machine shop or 1800 get a lawyer!...good luck on those in the bell housing area, PS you didn't try to save a buck by installing them yourself did you? By the way doesn't the Ford 302 use one head gasket upside down and one right side up?Hummmmm
 

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34toddster said:
? By the way doesn't the Ford 302 use one head gasket upside down and one right side up?Hummmmm

Front is front. Look for the square gasket corner by the front lower head bolt. One of Ford's better ideas. :thumbup: Some aftermarket heads cover it, but can be seen with mirror.

Corner in front.... OK
Corner in rear...... BAD

No corners either end....... some aftermarket gaskets made without corners..... Your guess is as good as mine if they are on backwards.


See bottom right picture for corner.

edited: note Felpro has corners
 

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