nathan65

Hey everybody. Got a strange question. I have a 1965 mustang with a 68 302 block and 65 289 heads. I had an overheating problem with the motor and very long story short, I ended up rebuilding the top end as I thought I may have had a head gasket issue. I had read about drilling steam holes in the heads to help with overheating. Well, I'm a dumbass and I drilled the holes in the wrong place. I thought that the triangular water passages in the block were the steam holes. I ended up drilling three new holes in the heads directly opposite of the existing water passages on the heads. What have I done and will this negatively affect anything?

109jb

Give us a picture so we can see exactly what you did.

gooser

i do not have a good feeling about this one.

2+2GT

"Steam holes"? What steam holes? I've been working on these things for over 30 years, and if there's steam inside the engine, it is already MASSIVELY boiled over. The only problem anyone ever has with cooling at the interface between the block and heads is when some dingus puts the head gasket in backward, with the large water openings toward the front. Then what happens is coolant, entering the block at the front, is drawn through the large holes into the head, and back to the radiator, and no coolant goes to the rear of the engine,causing the rear cylinder area to overheat and boil the stagnant coolant back there. There are no "steam holes". The triangular holes in the water jacket are core support holes, just like the round holes on the outside of the engine, which people mistakenly call "freeze plugs". These openings are used by the foundry to hold the sand core for the cooling jacket in place in the mold when casting the block. After casting, the sand is flushed out of the iron block, making it hollow. If all you have done is make the triangular holes round, it should have no effect, except of course as always you must be VERY careful to put the front of the head gasket toward the front. Now go find the magazine that told you about "steam holes", throw it away, and cancel your subscription.

Typically, rebuilding a Ford engine involves boring the cylinders oversize, which thins the "thinwall" casting even more. This allows more heat into the coolant, and usually requires replacing the 2-row radiator with a 3-row. It's actually getting hard to find 2-row rads. If you experience overheating, install a fan shroud as used on HD cooling and AC cars. If this is not enough, add a 6-blade rigid fan, not one of those awful flex fans. If you don't like the fan nose on the highway, and want to improve power and economy, use a 6-blade clutch fan with a thermal clutch. The thermal type, a little more expensive, is thermally controlled by a spring on the front, and freewheels when the air coming through the radiator is cool enough. You can stand next to a car equipped with one of these on warm days when it's idling, and hear the fan cutting in and out, similar to, but much more simple than, an electric fan.

67t5ponycoupe

When installing Trick Flow head on an early block there are holes that must be drilled in the block to allow coolant to get up into the head. It sounds like these are the type of hole you have drilled. I'm thinking no harm no foul but it is hard to say without see the holes you have drilled.

2+2GT

Sounds like a good reason to choose a different head.

nathan65

Thanks for all the quick replies. I'd love to send pics, but already bolted the heads on. I figured I'd just give em a try and see what happens. I'll try to explain where the holes I drilled are a little better: If you are looking at the bottom side of the head - the part that mates to the block - with the exhaust side down, directly above the holes for the head bolts there are three triangular holes that match up with the block for coolant passage. I drilled the new holes directly opposite those triangular holes, directly below the other head bolt holes. Hope that makes sense.

nathan65

Just an update for those who care. I reassembled the engine with the miss-drilled holes and all seems to be working just fine. Motor runs strong and most importantly, it is running cool all day. Never gets above 182 degrees. As for longevity, only time will tell. Thanks again for all the replies.