I recently bought a 31 Ford coupe with a 50 flattie, bored 80 over, with 7500 miles on it. The previous owner mostly putted around town in it. The car has a newer Walker radiator with a 4lb cap. I consulted with the Walker techs and changed to a 7lb cap and proceeded to drive the wheels off the car to far away car shows (They're the most fun kind) that involved multiple hours of interstate driving at 65 mph. Upon exiting the freeway on my most recent excursion my water temp soon went from 170 to 220. I pulled over and had steam coming out the tailpipe. I shut her down and got flat bedded the remainder of the trip home. (Thank goodness it was dark. It was embarrasing.) I pulled the heads and found the driver side head gasket blown at the rear cylinder. I guess the wind licking my open engine compartment at highway speeds was keeping the motor cool. My question is do you think the gasket was on it's way out (Due to not being torqued correctly or what ever) or did I drive her to hard? I'm hoping it isn't the latter because I would hate to be restricted to local driving only.
Driving a flathead at 65 on the freeway hardly cons***utes abuse, unless you have a 5.4 spool and 25 inch tires and she is turning 4200 rpms at 65. More then likely it was a preexisting condition (maybe that is why it was only driven around town???). Check for a cracked or warped deck face and make sure the heads are properly torque on the next go around. Good Luck
If the gasket is in there right and the torque has settled down, sustained speed won't hurt it. Look over the area carefully for damage, slide a wood chisel and/or your fingernails over everything to be sure there isn't an invisible speck of an old gasket in the way, then torque it down. Re-torque several times...the first time, back off each nut a slight amount then retorque, after that just run the torque. It should settle down pretty quickly. I have heard the newer teflon/mystery stuff coated gaskets work well.
Blown head gaskets are not unknown in a flathead. If you left it in the garage under a car cover it would not have blown so, in that sense it was your fault. Put in a new gasket and drive it. But check the bolt holes are clear, the block and head are flat, and if the head or block has been planed you may need extra washers under the head bolts.
Flatheads, blown head gaskets, Not at all uncommon. Go over it as Bruce said, and you're back in business. Retorque, after the initial start up. 4TTRUK
Its possible the brand of head gasket used was the problem. In the past import junk gaskets on the market caused some problems to those who had no idea the gaskets were poorly made. As long as the deck and head are relatively flat a good replacement USA made gaskets should take care of the problem. It would be best to replace both gaskets so you have a matched set then you will be good to go.
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