flathead noise

50 ford 8ba flathead..the other day while i was driving it, driving it hard as usual it suddenly started making a nasty knocking sound...and seems to not be running well anymore, i made it home, than decided to take it to the garage to see what i could do and suddenly all of a sudden the noise went away, and seems to be running okay...maintained good oil pressure and was not overheating...what could this noise have been? luckily i picked up a merc flathead that ill be building sooner than i thought i would!

 

might not have been from the motor.. if it aint broke, dont fix it. that flathead will run on 2 cylinders, its tougher than you think. check the oil, check the clutch... if it everything looks good go for a drive and dont worry about it.

 

At that point I'd drive it even harder and see if you can get the noise to come back....did the oil pressure drop when it was making the noise? What kind of oil do you run? If you dont run none detergent oil, debris can clog the pick up.

 

i'm running non detergent straight 30, and no, oil pressure did not drop, could it be that a piece of carbon broke off from inside the head and was rattling around in the cylinder until it eventually broke apart and went out the exhaust?

 

How many miles are on this motor?

I would do a compression test. I had one that every once in a while would make a god awful racket that would come and then go, Never lost performance or oil pressure. One day I pulled the heads to find that the piston was coming apart, the top ring had broken into many pieces. The pieces of the rings were stacking on top of each other and breaking off the top of the piston, then the ring pieces were exiting and dancing around in the chamber. Good thing I had cast heads on her, I would have killed aluminum heads. I had holes in three pistons and she still ran great.

They are tough motors.

 

can only speculate...possibly a valve seat came unglued bounced around and went back in place?

 

50's didn't have valve seats, did they? I though all (most?) of the 8BA searies have the seats ground in the block itself.

 

50s Ford (but not Merc) had pressed in seats and I've seen them come loose and get chewed up and spit out. Compression test will tell the tale.