Help, thrust bearing out on rebuild

[Pat McCabe]

Just had a 201cu rebuilt and my mech that rebuilt it said it did not sound right after star up.

He said thrust bearing was going out due to connecting rod pressure on cylnders 2,4,6

So he ordered new rods for 2,4,6 from andy b.  and says that the head gasket does not fit and FROM THE FACTORY THE BORE WAS OFF

is this possible

Any help would be very appreciated

 

[mechresto]

1 hour ago, jeff ross said:

Just had a 201cu rebuilt and my mech that rebuilt it said it did not sound right after star up.

He said thrust bearing was going out due to connecting rod pressure on cylnders 2,4,6

So he ordered new rods for 2,4,6 from andy b.  and says that the head gasket does not fit and FROM THE FACTORY THE BORE WAS OFF

is this possible

Any help would be very appreciated

 

Jeff

The issue of the bore being "off" from the factory is about as possible as me being the president.

All six holes were bored simultaneously. However...that doesn't mean that at some subsequent time in its life that it wasn't rebored at OH. There the cylinders are done individually and it's not out of the realm of possibility that it was not lined up correctly. If your guy had done his rebuild by the book...it would never have made it through assembly. Checking rods for straightness, the line bore on the block, side clearances of all of the rotating assembly should have been done as the engine went together.

 Take your old rods to any reputable machine shop and they can tell you in seconds if theyre bent or twisted. It's far more common than most realize.

In the "old days" we had the rod testing, straightening and resizing equipment all set up on the bench....because they got used constantly.

EVERY rod was checked prior to assembly.

I can't recall offhand, perhaps someone else can chime in...but are your piston pins full floating or semi floating in the 201?

If they're semi floating...check the centering there as well, a bad fit there can induce excessive side load on the big end.....

The head gasket issue....

Do you have the correct one? 

[Pat McCabe]

He had the rods checked for straightnes at a engine shp,that wasn't it,he also checked crankshaft numbers and that was correct also said the rods were centered.

So I believe when he bored it he had the machine off,somehow

Thanks for your help mechrestro

 

[PT81Jan]

I totally agree with mechresto.

Any clearance is checked prior / while assembly ... and if the rods have been checked and they where ok, what should be better with the new ones ? Not to predjudge someone, might be that I do not see the whole picture ...

When I have rebuilt my motor (201), the bores where indeed slightly out of line. Let a machine shop bore it larger to get it perfect in line. Pressed sleeves in which matches the 218 pistons. The sleeves might not have been necessary, but I wanted to be on the safe side in case the wall to the water jacket was too thin. Just a thought, might be too late for your motor ?

click to enlarge

Some info regarding thrust bearing failure: http://www.4secondsflat.com/Thrust_bearing_failures.html

And last: If the cylinder head gasket does not fit, I see two possibilities:

1. wrong gasket

2. wrong mechanic (aaah, now I did prejudge again, sorry)

click to enlarge

Edited November 1, 2017 by PT81Jan

[Merle Coggins]

As I recall, on the 23" engines the rods have a slight offset to one side or the other. Essentially there are 3 of each offset. I remember when I was assembling my engine I had everything layed out and I was dropping the pistons into the cylinders. I mistakenly grabbed the wrong one and when I got it in the rod fit very tightly onto the crank. I knew something was wrong and upon investigation I saw that I had grabbed the wrong one. I pushed it out again and dropped it into the proper hole and all lined up as it should. 

I have to wonder if they got at least one rod in the wrong spot so that the offset is to the wrong side. This would explain their thinking that the bore is off. It's probably not the bore, but the con rod offset is wrong. 

Merle