mvandale
Member
Yup, ran it with valve cover off...nothing unusual. Just humming and clicks of drivetrain...all valves opening and closing fully.
Need Help -- Knocking 440 Sound
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Yup, ran it with valve cover off...nothing unusual. Just humming and clicks of drivetrain...all valves opening and closing fully.
PurpleBeeper
Well-Known Member
I would double check the valve gear on #1 a third time. Maybe swap in 2 lifters, pushrods & rockers (you don't have much lobe wear yet & what do you have to lose?) Otherwise, it must be a piston or wrist pin. You've checked everything else. There are some REALLY good pieces of advice above. The good news....you CAN replace one piston/rod with the engine in the car and pulling just that one head (I've done it). With so few miles on the motor & *assuming* you didn't balance the engine or know the piston/rod weights, I would be inclined to replace #1 piston/rod/rings and run it.
It sure sounds like tear down time. Only other item to check is the intermediate shaft bushing. Just a stab at the gear and bushing to make sure it is ok. I did have a small block that was rebuilt for a customer that had no bushing. I know it was messing the timing and distributor up. Can't remember any noise but there is lots I don't remember.
Does your carburetor still have all of its throttle plate screws? Or anything else missing from it? 120-150 psi range in a compression test on a 1000 mile engine sounds like a bit much.
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mvandale
Member
Thanks all. I've resigned myself to pulling at least the driver's side head to look at/remove #1 piston.
The distributor drive & bushing are good... checked those when I tore apart the timing set.
Will post the findings this weekend. No time until then.
Hey, maybe my luck will turn and something will be dancing around in the cylinder.
The distributor drive & bushing are good... checked those when I tore apart the timing set.
Will post the findings this weekend. No time until then.
Hey, maybe my luck will turn and something will be dancing around in the cylinder.
Before you pull the head, remove the oil pan first and check to see that the crank isn't hitting the pickup. I had that happen once too, and it does sound like that, not to mention that it is in the front...
Looking in that hole through the plug opening could shed some light. Also once the intake is off look closely in the port. Same with the exhaust. Possibly a valve seat? Again looking through the plug hole you should be able to see the seat. Playing with the spark might tease it with the combustion pressure under fire.
mvandale
Member
All clearances we're checked when I replaced the rod bearings...no hitting of oil pickup or anything else. I wish.
rtdodge1
Active Member
check your harmonic balancer and crankshaft end play.
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Oh my goodness that sounds horrible!
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Man, I really hope it's nothing too bad, and I'm really curious what it is, so I'll be waiting to get "the report".
The 421 in my wife's GTO had a bad crank end rod bearing, and I mean BAD, in that one half was cracked into 2/3rds + 1/3rd pieces, and the other half was worn. I don't know how long it was that bad, but the oil pressure was low when hot at idle, so I suspected that it would need a rebuild. I was driving it when I noticed the rod knock, but only within a range of RPMs, say 2k to 3,500.
I'm grateful to God that it didn't throw a rod, and it had been rebuilt with some good performance parts and fully balanced rods and JE pistons before we bought it, but the timing was way too advanced and that could have beat that bearing up before we "rescued" the car when we bought it.
Mark Barnes
Well-Known Member
Pulled a skirt ALMOST all the way off a piston once. Only one side broke. Every time the piston would go up/down, the loose pin would make a hellish noise. Wife thought it was a collapsed lifter and DROVE IT HOME. Crikey!
Pulled it apart and found 2 broken/cracked skirts. Changed them all, honed and re-ringed, and no other issues! Even a blind squirrel finds a nut sometimes...
mvandale
Member
Done. Harmonic balancer was checked (all good), and crank end play was double-checked...once when front timing was checked and again when rod bearings were checked and replaced. Also checked main bearings & all was in order.
Mike67
Well-Known Member
Shot in the dark what was your pv clearance?
Are your springs dual? Maybe an inner spring or keeper broke and valve is slapping the piston?
Are your springs dual? Maybe an inner spring or keeper broke and valve is slapping the piston?
Ernie ingling
Well-Known Member
With a stethoscope ckeck fuel pump. Is knock louder
Not a broom stick a stethascope
Not a broom stick a stethascope
Challenger340
Well-Known Member
That sounds to me like a 'collapsed' Piston.... and If you shorted the plug on #1 and were able to change the sound when re-attaching ? then it's probably on that #1 Cylinder.
The definition of "collapsed" Piston being.... that it has LOST the ability to go from OVAL when COLD and become ROUND when HOT to "fit" the Cylinder.... and what you are hearing is the now excess skirt clearance on the now "tweaked" Piston structure slapping around in the Bore across the entire temp range.
It won't change much from Hot or Cold... you will hear it all the time.
Lots of causes for this....
the most prominent being upon initial Engine startup/run-in someone forgets to add coolant until running and HOT.... then water gets added to the Rad and enters the Block at the front if the Block(Cylinders #1 & 2).... causing them to shrink rapidly and pinch the superheated Piston "tweaking it out of round" or worse yet scuffing the Piston skirt ?
Who fired/ran the engine initially ?
The definition of "collapsed" Piston being.... that it has LOST the ability to go from OVAL when COLD and become ROUND when HOT to "fit" the Cylinder.... and what you are hearing is the now excess skirt clearance on the now "tweaked" Piston structure slapping around in the Bore across the entire temp range.
It won't change much from Hot or Cold... you will hear it all the time.
Lots of causes for this....
the most prominent being upon initial Engine startup/run-in someone forgets to add coolant until running and HOT.... then water gets added to the Rad and enters the Block at the front if the Block(Cylinders #1 & 2).... causing them to shrink rapidly and pinch the superheated Piston "tweaking it out of round" or worse yet scuffing the Piston skirt ?
Who fired/ran the engine initially ?
mvandale
Member
Thanks, Ernie, fuel pump checks out good. Even ran car with fuel pump disconnected...no change in sound. Fuel pump pushrod also checked.
mvandale
Member
I'm tracking. Sounds like a good option.
Engine was initially fired by builder. First for a break in then was dyno'd.
I have no idea how he did it, so could be. Oddly, the engine has run without this type of noise, adding to the mystery.
Nonetheless, all signs point to a problem in#1 cylinder.
PRHeads
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Taking everything you’ve already checked into account.......
Before pulling that head, take another look at the pushrods & rockers on #1, to make sure the pushrods are properly seated in the rockers(or the adjuster screws).
My first thought was a valve hitting a piston.
Aside from that, it has the “piston hitting the head” sound to me, or something imbedded in the piston hitting the head.
Before pulling that head, take another look at the pushrods & rockers on #1, to make sure the pushrods are properly seated in the rockers(or the adjuster screws).
My first thought was a valve hitting a piston.
Aside from that, it has the “piston hitting the head” sound to me, or something imbedded in the piston hitting the head.
mvandale
Member
Thanks. I've taken the valve train apart a couple of times, checking for collapsed, stuck, or improperly installed items... even swapping out some items with no change in sound.
Not sure if I'm hoping for piston to head contact issues, but any identification and cure would be welcome at this point.
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