Tales From The Oil Pan. - Now With Video

I think on an old Dauntless that is typical.

 

Detonation looks to be the culprit. I checked my book again and it definitely says 5* so I bumped the timing up to 10* and the knocking seems to have gone away.

just a quick ride a couple miles around the neighborhood.

I’ll update y’all here with further developments.

 

It did.

 

Not making sense to me. Another 5º BeforeTDC? More advance would aggravate a knock.

If it was detonation, I hope the pistons are not damaged.

 

It is possible for too retar

It is possible for too retarded of spark to cause detonation too. From Detonation (aka Knock) | Causes and Prevention:

Highly Retarded Ignition Timing

While less likely to occur compared to overly advanced ignition timing, running
severe amounts of ignition retard provides a long window for hot spots in the chamber
to pre-ignite the mixture and cause two asymmetric flame fronts, often resulting in
detonation.

You would think it would be more than 5 degrees to cause that. Also why is it changing? The bolt was loose? The distributor gear is going away? Also doesn't make sense it needs to be 10 degrees at idle to run right. Hard to say what's going on.

 

I’m just relieved it doesn’t have to pulled just now and I can get on to the next big project. Hanging pedals!

 

I'm wondering if the timing chain jumped a tooth?
I'm also used to 40-50 psi oil pressure at road speed. If your bypass spring in the pump housing is weak, or the bypass piston hanging partially open, it could lead to lower oil pressure.
-Donny

 

Thats a lot of noise to be fixed with just some timing advance. Something is/has come apart. Check timing gears first. 25psi at 2K is too low. Should be 35-45 from my experience..

I be that speedo cable got kinked when a transfer case got dropped while still attached...

 

I cant hear enough to tell anything about the noise, but that is NOT enough oil pressure.

 

I just sent a forklift in for an engine replacement that had the same issues. Knock under load, low oil pressure but ran fine. Turns out is stacked a rod bearing...
I don't mean to scare you, but it sounded exactly the same.

 

Kind of a rule of thumb that I go by. 10 psi per 1000 rpm. Three things that deal with oil pressure are rpm of oil pump, oil viscosity, and oil clearances.

Fsm states 33 psi @ 2400 rpm

 

it ran better at 10* and I’m going to just leave it like that for now.
I took out all the brake and clutch gear yesterday for the hanging pedals swap. Then the 4speed along with that. I have a 231 on an engine stand if needed. I’m just going to ignore the 225 until all the other stuff is done.

 

It would be super easy to slip in new mains and rod bearings right now. I'm mad at myself for not doing just that when I took the pan off last week but I have 55psi cold and at least 30psi hot idle. If you pull each rod/main cap and the crank looks decent I would slip in a new bearing and check with plastigauge. New bearings that are properly sized by confirming with plastigauge will increase oil pressure and could fix the knock. It would be a really cheap and easy fix and if it works you may never need that 231.