Chevy Tri Five Forum banner

Engine Mechanics Please Advise 283 Knocking

6.3K views 22 replies 18 participants last post by  hotrodg726  
#1 · (Edited)
It is a never rebuilt original 220hp block with 63,000 original miles. Heads are redone with hardened seats. No knock when the engine is cold. As it warms up it starts a single medium loud knock. Not as loud as a rod or main sounds. No decrease in power. But too annoying to ignore.
I am thinking to pull the valve covers and see if I can tell anything cold or also running. I am hoping it is just a bad hyd. valve lifter which I believe them to be originals. Any help on how to proceed is appreciated!

PS. It is louder when winding down than reving up
 
#3 · (Edited)
I doubt engine temperature would change a loose harmonic balancer keyway or key, but I had that happen to me. When I was a kid, 2 oldtimers told me that I had a rod starting to knock. The bearings were worn, but none were spun. It sounded exactly the same after overhaul. A $5 junkyard harmonic balancer and a new key fixed it. It's been under my workbench for 30+ years.

You can pull the plug wires one at a time to see if you can isolate it to one cylinder, it didn't change on mine.
 
#4 ·
I repaired a guys SBC that knocked once by changing the timing chain. It was old, had a lot of slack and was hitting the cover. I could see the marks very easily. But it still knocked. I ended up shimming a rod bearing with brass sheeting. The last I heard from him about it a couple years later it was still doing just fine.
 
#6 ·
I intend to fix the car no matter what. If it requires pulling the engine (which needs to be done anyway because of rock hard deposits in the 283's block's water jackets) then so be it. The question then becomes to purchase a pre-1968 no emissions rebuilt shp 327 (about 350hp) or rebuild the original 283 which is the actual engine that came in the car? I prefer the 327 option but I also don't want to devalue the car when it is sold at some point (by my heirs!)
 
#9 · (Edited)
406 in 327 or 283 clothing even better. I am assuming you kept original stuff for heirs that prefer 3 on the tree over tremec. Usually louder on deceleration is rod noise, fluttering at flash over is wrist pin. Lifters and timing chains and balancers/flexplates/torque converters/etc. can be listened to with engine stethoscopes and/or length of 3/4 inch heater hose held to your ear and placed close to the suspected failed part. Good luck with your repairs.
 
#15 ·
#16 · (Edited)
X2 on the timing chain knock.....had one that knocked sooooo darn bad EVERYONE told me it was a rod...was tearing down the motor and there it was plain as day....the chain was slapping against the timing cover....since the motor had roughly 60,000 miles...I installed a new chain and gears....and reinstalled the motor.....the 62 bel-air it was in still runs to this day.....THAT was about 20 years or so ago
 
#17 ·
X2 on the advice given by irishsteve in post number 10.
I had that happen to me once and it drove me up the wall til I found it... completely by accident.

In my case the spring wasn't broken, just weak enough to let the fuel pump drive rod slap back and forth between the cam and pump arm causing a 'knock'.
 
#18 ·
Thanks so much! I will check fuel pump out first!
 
#23 ·
if it is knocking bad enough that he can hear it, then it needs more than a set of bearings slipped in it.