Knock/Bearing Bits

doug.nichols

doug.nichols

Senior Member
Hello folks,

Trudy developed an engine noise that met Les Andrew's characteristics of a rod knock. I dropped the pan to adjust bearing clearances (my first time). The good news was that there was very little sludge and the oil pump was spotless. The bad news was that I found metal pieces in the dipper tray (see attached picture). So, I have some questions that members may be able to help me with:

1. Does it a appear that the pieces are from a babbitt bearing? I have not yet taken the caps off of the rod or main bearings. Attached is a picture of a rod cap in case that is helpful in answering this question.

2. Whether it is a babbitt or i:confused:nsert bearing, it it possible to replace a single bearing with a new insert bearing with the engine in the car? I am not aware of anybody in my area who works on Model A engines and I am not set up to do so. Should I be prepared to ship the engine somewhere for repairs?

Thanks for your help.

Doug
 

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Well I would figure out which cylinder is knocking by shorting out each spark plug one at a time. You could also just pull all the caps now that you have the pan off - Just label them!

You defintely have babbitt bearings just by the way of the look of the rod. If those chunks are from the babbitt, and the bearing is bad, you can't just replace it with an insert. Your engine has to be set up and bored for inserts.

You might get lucky and it is not a bearing. Check the gears along with the oil pump for any damage.
 
The center main is usually what gives out first. This is usually caused by fast driving with an non counterweighted crankshaft. This was one of the shortfalls of the Model A engine.
 
Inspect the bearings. If a rod is bad you can have it repoured and machined without removing the engine.
 
If one bearing is bad the rest may be close behind. You can buy a set of rods with insert bearings. Inspect the journals. Use a 1 to 2 inch micrometer. They should be round and not tapered within 0.0005 inch and shinny. As others have suggested, pull the cap on the center main too to inspect that. If the mains are bad it is time to get overhauled. You may have to withdraw some of your 401K.
 
Yup...you got problems. I went through this in June and changed oil just cause. Same amount of Babbitt as your pic. We were lucky to have made it home from our trip. Engine banged and rattled for 200 plus miles. Center main for sure in my case. Stethoscope the center main bolt on the driver's side while running. Pulling the engine and going inserts. I'm personally done with Babbitt.
 
Here's a 300% enlargement of your picture. If the solution is a rebuilt engine in the neighborhood of $4000, consider buying a Burtz engine.
 

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At the risk of opening a can of worms..

If I was to consider a short or long block from one of the engine shops that get good reviews on this web site, what are the opinions out there about babbitt vs insert? To aid in your feedback, I live on an island where the maximum speed limit is 40mph. I do not tour. It is hilly here. My normal drive would be a 20 mile loop and it would occur once a week maximum. I have a Mitchel gear splitter for the hills.
 
Engine shops are back logged. I'm on a waiting list for Antique Engine Building. I spoke with Steve at Bert's 6-8 weeks ago. There were 40 ahead of me. I just finished my shipping crate. Pulling the motor after Labor Day. I want it crated and ready to go when I get the call.
 
Inserts are much easier to work with rather than babbit these days. Babbit works good if done properly, the only issue is it is getting harder and harder to find people who know how to do correctly.
 
Bob Bidonde said:
Here's a 300% enlargement of your picture. If the solution is a rebuilt engine in the neighborhood of $4000, consider buying a Burtz engine.
Click to expand...

Does anyone know what a completed Burtz engine costs. The "kit" is ~$4000 but what is the turn key engine going to cost someone. Looks like you need pistons, rings, cam, bearings, gears, etc. on top of the "kit".
 
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