Bent push rods on the left head (facing the carburetor). Purchased two heads (might as well, 274 hours on engine) and installed. Right head reads 90 psi compression, left head absolutely no compression.
Checked the valve clearances at top dead center. Both valves 0.004". Did a double check by having the exhaust valve completely open while adjusting the intake. Again 0.004". Did the reverse, again 0.004".
Possibly a bad "new" head was sent to me. They were both labeled "Original B&S Parts", and came in B&S boxes.
What gives? Prior to tear down of old heads, the bad cylinder had 60 psi with bent push rods. Now it's zero.
Slip a pencil down the plug hole and confirm the valve timing with respect to piston travel.
You can cross over the pushrods so the valves are working backwards.
But the $ 60,000 question is what caused the pushrod to bend in the first place ?
when you installed the valves into the new heads, did you lap the valves into the head and see where the seat meets the valve face? If the valve guide slipped, are you sure that it did not bend the valve a little bit? obviously you were able to remove the valve so it could not have been too bent but may be worth checking. with the piston at top dead center at the beginning of the cycle, both valves should be slightly open. then like Bert said, make sure that the valves are doing there thing while the piston is doing its thing. The chances of it being a bad head are slim to none. it has to be an issue with the valves.
Just my 2 cents worth.
Are we sure its not a broken connecting rod sounds kinda fishy cause even with a bent valve you can still get 10-15psi, was the travel of the piston checked when the heads were off?
Are we sure its not a broken connecting rod sounds kinda fishy cause even with a bent valve you can still get 10-15psi, was the travel of the piston checked when the heads were off?
