I would like to press the top bush into the conrod. I made a tool to do the job, which took out the old bush with no hassles while the conrod is still assembled in the motor. I am freezing a new bush to contract it before pressing it back into the conrod. My question is is there a solution like lock tight that should be used? As the old bush had rebalances of something left in the conrod after I removed it.

Would it cause any damage if I heated the top of the conrod and freezed the conrod to press it in? Or should I just use heating the conrod then press the bush in? Or just freeze the bush and press it . Only?

DO NOT HEAT THE CONROD!!!!...

If you have a genuine BSA small end bush simply press it into place using the correct tool...

You can 'freeze' the bush if you choose to make fitting slightly easier...though that is not strictly necessary..
The conrod small end bore and the outside diameter of the bush are sized to produce the correct press fit with both pieces at ambient temperature...No Loctite (or similar) is needed...

If the bush is slack in the conrod Loctite or anything similar is not a suitable 'fix'...
Either an oversize small end bush should be made to restore the correct fit between the two components or the conrod should be replaced...
If the rod eye is oversize and is not round (measured with an internal micrometer) then the conrod should be replaced anyway...

After fitting the new bush carefully drill the lubrication hole and then ream to finished size with a suitable, sharp, hand reamer...
Ream to the recommended pin clearance and then fit the piston and oiled gudgeon pin to test the fit...

The piston should 'fall' under its own weight...ie..the pin should move/turn freely without resistance but not be 'slack'....Ian

email (option): ian@wright52.plus.com

Hi Ian... I wish I was more patient to wait for your reply. I heated the conrod and pressed the bush almost all the way through. HOWEVER the bush flared at the press end. I put so much pressure on it that I bent the sizable G-clamp I was using to apply pressure. I guess that I have damaged the conrod and will now have to disassemble the motor and put in a new conrod. Does the heating wreck the conrod?

Hi Ian, Bryce.

This is the tool I am using to inset and extract the smallend bush,
The "deep" side of the nut towards the bush to extract,
The "Shallow" end of the nut towards the "far" side of the smallend when inserting the bush,

But I know you could use also just a plain long screw and nut,
With a another bush/spacer on it to press the bush in and out.

Ian,
You mentioned drilling the oiling hole.
I see that on the current bushes sold on eBay there is no hole
And no thread/score inside and they are plain.

I have used in the past smallend bushes with X shape scores inside,
Which meet at the already drilled oiling hole.
Shouldn't this kind be used?

I disassembled 2 motors which did not have the scores on the inside of the smallend bush,
And they seemed happy also..

Cheers,
Noam.

email (option): noam10@gmail.com

Noam...The bushes with the oil scroll in them were probably original bushes...I haven't seen this detail in any pattern ones...

The ones on e bay without oil scrolls are more than likely from Alpha bearings....

Few engines have oil scrolls machined into the small end bushes and no doubt they are there just to give a slightly easier path for the lubricant to move along the pin...

I have seen a number of M20 engines where the rod and pin show signs of overheating, so I guess every little helps...

For that reason it is important with the M20 small end bush to ensure it is not too snug on the pin after reaming to finished size...

Bryce...It sounds as if your tool for fitting the small end bush is not working correctly if you have splayed the bush...This will not happen with a correctly made tool...There may also be an underlying dimensional fault if you are having to exert that much pressure to get the bush in..(and/or the bush has gone in out of square)....

I'm also loath to make a recommendation with regards to the conrod...

Personally I would replace it but that is for you to decide...In any case I think you need to go back to basic principles.

First sort out the tooling you are using and then try to acquire a more thorough grasp of the various aspects of the job before proceeding...Ian

email (option): ian@wright52.plus.com

Thanks Ian !

email (option): noam10@gmail.com