The Stovebolt Site Forums The Shop Area Engine Shop Slight knocking coming from the engine what to tighten.

I'm starting to hear a slight knock for the engine and I think it is time to tighten the rods and bearings. Any advise on how much to tighten or what to look for once I have the oil pan off?

Isn't "slight knock" like "being a little bit pregnant" or have I missed something? LOL---

You are probably looking at a rebuild. Pull the pan and rod caps first and check their condition then pull the mains. No such thing as tighten them up.

A little more diagnostics would be in order. You can start by pulling one plug wire at a time, that will usually cancel out a rod knock.

Which engine?? Babbit rod bearings, the only way to tighten them up would be to file the bearing caps. Not the best idea though. Probably like vette said, need to pull the pan and check clearances and condition of rod and main bearings. Get you some plastigage and check clearances...
John

Guys, don't offer advice about things you don't understand. Adjusting rod and main bearing clearance by changing the shim pack was something we did frequently on the Babbit-rod engines back in the 1950's and 60's. I sent him a PM about how to do it.
Jerry

Tighten your sphincter, because it's probably going to need a rebuild.

A little more research and a little less smart [censored] goes a long way in this hobby .......

Yes, Don, I agree with you!
Jerry

i had a slight knock at idle when hot, when my 228 was in my 40. it didnt cost me a thing to fix it. i increased the idle speed about 50 rpm and the knock went away. so depending when the knock apears or is noticable may be all it will take. if not what ever hot rod told you will be the correct way and most cost effective

Sorry, I didn't think they used shims on the babbit rods....
Knew they had shims on the insert rod bearings, figured the babbit rods were machined to size after they were poured.

Every time someone besmirches the Babbitt bearing engines I just smile, drop the oil pan, remove a shim or two and keep on driving. Whereas the guy with insert bearings with a rod knock is screwed.

The babbit is a lot softer than an insert bearing and the clearance goes away quicker, so it is a serviceable fix that most all babbit engines were designed to remedy back in the day. Model A's and T's also were common to shim to adjust clearances.

Insert bearings are lined with babbit. Its just they are not poured/scraped... but applied with much more precision. So we all still have 'babbit pounders' if you think about it

Chevvy/GMC/Ford trucks had insert bearings in the early 40's. My 42 Ford and 43 GMC had them as original equipment. Not sure why Chevvy took so long to get them out of the civvy engines.

And one man's 'knock' is another man's 'tap'. Rattles seem to be universal.

Times were different back then. Labor was cheap and parts were expensive. I'm guessing they stayed with the serviceable bearing rather than the replaceable bearing for financial reasons.

There used to be shims for the standard insert type bearings.
I would not recommend removing material from the caps, unless you are doing resizing the bores.