I have a bad knock in the engine of my 1927 Nash Ajax

[Pvoyles]

I have a bad knock in the engine of my 1927 Nash Ajax. I have taken the oil pan off but I cant see anything that is loose. There is good oiling it appears. The only thing that I noticed was the oil pump gear did not align with the drive gear causing wear on the bottom of the pump gear. I am not versed on the flathead engine and don't know what  the next move should be. I am going to need a timing gear if anyone has a suggestion where to find one. It's a Formica gear with Ajax stamped on it. I broke some teeth when I took it off. 

[31nash880]

Nice to see another Nash. Not many around.

Mine is a 31 with twin ignition. Interesting car for a newbie to car of this era.

I also have a knock. Only under load so hard to diagnose. Just changed timing chain. Loose enough to hit block. Hoping that most of it. At same time found both motor mounts broken. Engine just riding on the chassie. 

Many people here will try to help but few nash specific. 

[Larry Schramm]

Have you checked the clearance of all of the rod & main bearings?  Also the thrust bearings for the crankshaft.  Don't forget that you might have an issue of cam chucking.  Just some thoughts.

[Oldtech]

Can you give a better description of the knock.  Regular bang bang, or just under acceleration or a random rattle, or anything else helpful.

[31nash880]

Sounds like a rod knock when accelerating and up hill. Will be dropping the oil pan soon to reinspect bearings and oil pump. Hope bearings are ok. Have to wait on water pump repair before I can drive anyhow.

[Oldtech]

A loose piston pin bushing is very hard to tell from a rod knock. however the bushing would have to be quite loose to sound as severe.  it's a case of check everything.. 

[Larry Schramm]

Here is a comment that I saw in one of the Model T magazines.  I have not tried it yet, but it does make sense and appears to be a simple test for proper clearance.  Just be sure to put oil on the piece of paper before you put it on the rod cap.

 

Here's a quote from Jim Lyons: "Put a small piece of newspaper that covers about 70% of the rod cap in place and tighten down the cap on the rod on the crank with the paper in place. If you can rotate the engine then it's still too loose.Sep 2, 2015

[mikewest]

Or use a micrometer to measure the crank journal and a inside  micrometer to measure the ID  of the connecting rod with the cap locked in place.

[JFranklin]

4 hours ago, 31nash880 said:

Sounds like a rod knock when accelerating and up hill. Will be dropping the oil pan soon to reinspect bearings and oil pump. Hope bearings are ok. Have to wait on water pump repair before I can drive anyhow.

A rod will knock most going down hill I always thought. Might try and short plugs to identify and amplify the knock. Plasti-gauge is easy to measure the bearing clearances.

[Larry Schramm]

If you retard the timing with the engine running, if it is a rod knock, it could diminish in loudness or go away with the timing retarded.