Engine knock with good oil pressure

I agree with the wrist pin noise. It tends to get louder when hot, where piston slap is more noticible when cold. Just an online thought, I couldn't hear it very well on the web.

 

I agree to pull (or short) the plugs one-by-one to see if the noise changes per cylinder for slap or piston pin suspicion.
Slap or wrist pin is getting more likely.

 

Ok,I just spent a few hours on this engine. Casting numbers says it's a 59 235 with a 57 # 848 head,it does have solid lifters and a mild 3/4 cam...
Started it up after sitting overnight and you can hear the funny noise slightly,kinda rattle,but really not loud.Shorted the plug wires one at a time and there was no difference in sound. Then ran the engine at a fast idle for about 10 minutes,let it idle and shorted the plug wires out,no change in the sound.The sound is more towards the front....
Yanked the plugs,blocked the throttle open for compression check....140 to 145 psi on all cylinders after three strokes of the Snap On gauge needle,80 psi on the first stroke...
I don't know,this is one strong ass running 235..The compression is great,oil pressure normal,uses about a quart of oil every 1000 miles. The knock or rattle noise is very slight but my friend and I can hear it.If you walked by the car with the hood open and engine running you probably wouldn't hear anything odd.
Maybe it's header "ping", maybe a slightly loose wrist pin,maybe cam gear backlash rattle..... The owner says he'll run it as is and no worries...

 

Sounds like wristpins to me.

 

And those can run a long time being noisy... they have a double rap to them, very distinct.

I would still listen with a wooden dowel to the timing cover, side covers and around the fuel pump. It does sound like a bottom-end knock has been eliminated as the cause.

Bob

 

Yeah,sometimes wrist pins can be heard at idle only......But the noise isn't a steady beat....Think of the noise an old tranny makes when you let out the clutch in neutral.Not roller bearing noise but gear backlash rattle.It's not the transmission in this case however.

 

is the motor missing any choke plate screws? i had a 1957 235 come in with a noise like that and after pulling the head, found the top of the piston "ball peened" by a screw that fell in the carb and was embedded in the piston.

 

Anything fixed and rotating would have a constant noise, so look for something randomly occurring. I would use the dowel trick on the bellhousing, flywheel inspection pan, etc. Loosen up the fan belt to rule out any bearing noise from the water pump and generator/alternator just for laughs.

Bob

 

I bought a motor/trans form a guy one time for dirt. He told me that it was knocking and would require a rebuild. Upon removing the trans, I noticed the pilot bushing had fallen out of the crank. Pushed it back in with some green loctite and ran the motor for years. YMMV, John

 

I am soooo stupid,did I say I was fucking stupid!!! The car owner pissed his pants he laughing so hard.He told me he took off the fan belt and the noise was still there. I just took off the belt and the noise in gone! Just the gentle 235 tappet noise as even as a church mouse chewing paper.
It has a plastic fan and one blade was just touching the damper pulley.When the engine was reved up off idle the fan flexs foward and the noise is gone.
A trim with the Dremel tool and it's all wonderful
Thanks for all the suggestions and help.I supposedly know to check the easy stuff first.
Good thing I'm a far better electrician than mechanic otherwise half the buildings in the country be on fire

 

I knew it has to be something absurd, always check the free shit first! And when in doubt, crack open a cold one or 7 and "drink" about it. The answer will come to you mystically.

Bob

 

Glad to hear it was a easy fix,the 235 in my 37 has a rattle thats been in it for a long time that I have located to the #2 cylinder. I wish it would be that easy to repair.

 

With engine noises I always suspect the worst.And I don't like working on engines.I enjoy suspension work,manual transmissions and rear axles but not them damn greasy engines.Even worse is working on someone else's shit because I'm just a hack mechanic.My wife the Pollyanna she is says I fixed the problem without actually fixing something that didn't need to be fixed
Jeff,yank that 235

 

I was lucky to get hooked up with an old guy (age 54.. hah!) in a shop I worked at. I was around 20, graduated from automotive school and at first I thought he was messing with me when he asked my opinion on ill-running cars, some real stump-the-band cases.

We covered noises, weird shit on the analyzer scope, ride complaints, etc. Of course whatever we caught, we had to clean and cook it, so we had to be right or warrant taking something apart for a better examination.

Sometimes the REAL cause falls into your hands while chasing something else, of course you should take credit for it.

Bob