B5Mopar
Member
Hello all,
Been following the site for some time now, but this is my first post. Looking forward to the interaction and what I can learn from the members here. Thought I would start by sharing my recent learning.
Recently purchased a 1973 Cuda 340 4-speed. Car has not been on the road much for the last 30 years, so took a little work to get her going again. New carb, gas tank, fuel line, plugs, wires, clutch, oil change, etc. Finally on the road and valvetrain had a fairly loud tick. Added Rislone to the oil and drove it 4-5 times over the coarse of a week hoping the additive could work some magic on the lifters. Car started missing and smoking, so removed driver's side valve cover and found a pushrod poked through a rocker arm on #5 intake. Replaced the rocker arm and thought all would now be well. Decided to do compression test before running the motor, and #5 cylinder tested at 28 psi. Tested again and got 40 psi. 3rd test 68 psi. 4th test 120 psi. Subsequent tests were all in the 120s. Other cylinders ranged from 125-155. Started the car up and the tick was still there. Removed valve cover again and found #5 exhaust rocker arm a little loose. Decided it was time to clean all lifters, so removed the intake and disassembled/cleaned all lifters. Surely this would fix the problem!
Reassembled and fired it up. The tick is still there. Still #5 exhaust. Bought an NOS Chrysler lifter and installed. Started it up - still ticking and rocker arm still loose. Bought a new lifter from the local auto parts store. Installed this one (the 3rd lifter) and started it up. Tick goes away briefly, but comes right back and rocker arm is still loose. So now I think it can't be the lifter. Replaced the rocker arm - still ticks. Bought two slightly longer pushrods - the first one temporarily stopped the ticking, but it came right back. The second pushrod stopped the ticking, but it was so long that the exhaust valve never completely closed and engine ran rough.
I'm now about 7 weeks into the battle and think it must be cam lobe wear. Since compression isn't great and the engine doesn't seem to have a lot of power, I decide to bite the bullet and pull the motor. Upon teardown, we find 15 lifter bores with an oil hole. #5 exhaust lifter bore has no oil hole. Attached is a picture of cylinders 1,3 and 5 and the lifter bores after we punched a small hole with a screwdriver (second lifter bore from the right is #5 exhaust). The metal was only about 0.010-0.020 thick. We also find valve guides to be quite worn and lots of carbon build up on the intake valves. Head bolts did not seem very tight and head gaskets are black and wet on both sides.
Amazing that the car ran this way for 106,000 miles and has no measurable wear in the the lifter bore.
Anyone else experienced this? I also can't explain why #5 intake threw the pushrod. Coincidence that #5 exhaust had no lifter oiling? And the compression test on #5 that I mentioned earlier. What caused the varying compression? Sticking valve?
Eager to get your thoughts.
Been following the site for some time now, but this is my first post. Looking forward to the interaction and what I can learn from the members here. Thought I would start by sharing my recent learning.
Recently purchased a 1973 Cuda 340 4-speed. Car has not been on the road much for the last 30 years, so took a little work to get her going again. New carb, gas tank, fuel line, plugs, wires, clutch, oil change, etc. Finally on the road and valvetrain had a fairly loud tick. Added Rislone to the oil and drove it 4-5 times over the coarse of a week hoping the additive could work some magic on the lifters. Car started missing and smoking, so removed driver's side valve cover and found a pushrod poked through a rocker arm on #5 intake. Replaced the rocker arm and thought all would now be well. Decided to do compression test before running the motor, and #5 cylinder tested at 28 psi. Tested again and got 40 psi. 3rd test 68 psi. 4th test 120 psi. Subsequent tests were all in the 120s. Other cylinders ranged from 125-155. Started the car up and the tick was still there. Removed valve cover again and found #5 exhaust rocker arm a little loose. Decided it was time to clean all lifters, so removed the intake and disassembled/cleaned all lifters. Surely this would fix the problem!
Reassembled and fired it up. The tick is still there. Still #5 exhaust. Bought an NOS Chrysler lifter and installed. Started it up - still ticking and rocker arm still loose. Bought a new lifter from the local auto parts store. Installed this one (the 3rd lifter) and started it up. Tick goes away briefly, but comes right back and rocker arm is still loose. So now I think it can't be the lifter. Replaced the rocker arm - still ticks. Bought two slightly longer pushrods - the first one temporarily stopped the ticking, but it came right back. The second pushrod stopped the ticking, but it was so long that the exhaust valve never completely closed and engine ran rough.
I'm now about 7 weeks into the battle and think it must be cam lobe wear. Since compression isn't great and the engine doesn't seem to have a lot of power, I decide to bite the bullet and pull the motor. Upon teardown, we find 15 lifter bores with an oil hole. #5 exhaust lifter bore has no oil hole. Attached is a picture of cylinders 1,3 and 5 and the lifter bores after we punched a small hole with a screwdriver (second lifter bore from the right is #5 exhaust). The metal was only about 0.010-0.020 thick. We also find valve guides to be quite worn and lots of carbon build up on the intake valves. Head bolts did not seem very tight and head gaskets are black and wet on both sides.
Amazing that the car ran this way for 106,000 miles and has no measurable wear in the the lifter bore.
Anyone else experienced this? I also can't explain why #5 intake threw the pushrod. Coincidence that #5 exhaust had no lifter oiling? And the compression test on #5 that I mentioned earlier. What caused the varying compression? Sticking valve?
Eager to get your thoughts.
