Big End Advise Please

[Hedd Jones]

As others have noted. This would have been consdered perfectly acceptable back in the day. I see no reason why it isn't now.

Put it another way, It is more likely that your factory standard little ends will give trouble!

[Ruairidh Dunford]

I have had no troubles with new little end bolts for over 20 years Hedd - have you?

[Ritchie Wilson]

I have bought several seized 3-bearing engines at South Island swap meets over the years and my memory is that all of them had little-end failure (on cylinder 1??) rather than the expected broken crank. This area of the engine would seem to have been a common failure point (as UK A7 web sites would suggest).

[Ruairidh Dunford]

In the mid 1990s a faulty batch of little end bolts got into circulation.

The heads of these faulty bolts had a nasty habit of snapping off, bouncing down one bore, up the next and jamming between the rod and cylinder wall resulting in a bent rod.

Seized little ends on number one rod of three bearing engines is a new to me.

[Mark McKibbin]

As my engine could have been rebuilt in the 90s I will replace the little end bolts as well as the big end bolts thanks Ruairidh. I am assuming from the replies that the shims may not be a bad thing and as the rebuild was some time ago and I am in Australia where there is a lot of American cars of this era, it is likely to have been a practice at that time, also the shims are on all caps so they look like they are meant to be there.

[Hedd Jones]

I have had no troubles with new little end bolts for over 20 years Hedd - have you?

Not on an engine I messed with. But on a 'running' engine I bought and used I had one come loose. 

I couldnt say when it was assembmed, but give the bore wear and when I guess it may well have been built before the period you mention.

[Ruairidh Dunford]

Sounds like it lasted a good long time before coming loose then Hedd - as mentioned, I prefer to use a spring washer and Loctite in favour of the tab washer.

Mark,  it strikes me that you may have access to some rather good facilities.  This is my rod boring jig, it was kindly given to me by a very good friend who also made the adaptor plate for my Boxford.  I have never seen another in the flesh but found one reference to it on the Internet (it is built for a Myford).  The trickiest issue is centralising the big end for boring (I mostly bore out old white metal to suit Pheonix cranks).  


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  boring jig 2.jpg (Size: 98.62 KB / Downloads: 385)

[Mark McKibbin]

Sounds like it lasted a good long time before coming loose then Hedd - as mentioned, I prefer to use a spring washer and Loctite in favour of the tab washer.

Mark,  it strikes me that you may have access to some rather good facilities.  This is my rod boring jig, it was kindly given to me by a very good friend who also made the adaptor plate for my Boxford.  I have never seen another in the flesh but found one reference to it on the Internet (it is built for a Myford).  The trickiest issue is centralising the big end for boring (I mostly bore out old white metal to suit Pheonix cranks).  

That is a very nice piece of kit, how do you adjust the height?

[Tod]

Mark,

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Mark,
Over the years I have overhauled a fair number of Engines mainly small to medium Diesels (1 to 8 cyl). I have only come across a "shimmed" big end once it was on a medium sized Ruston Engine. It did not seem a "Bodge" repair as the shims were fitted correctly and shaped accordingly. I know it was common practice to shim plain bearings on many other applications.
What thickness is the shim ? If it is only a few thou. it may be worth considering discarding the shim and scraping the bearing to fit the shaft.
When I fitted a Pheonix C/Shaft to my engine I made a mandril crankshaft size less 0.0005" and had it hardened & ground. I scraped all the rods to this and then finally scraped them to the New Crankshaft so the rod just fell under it's own weight when tightened. For what it is worth, my preference is to use a small 3square (triangular) scraper to do this. Always keep it sharp, giving it a wee rub up on a fine oil stone now and again, and don't try and use it blunt.

[Ruairidh Dunford]

Tod knows the set up well - he gave it to me!  Prior to that I scraped and blued as he describes.

The height is set up using cones and an adjuster underneath, everything is then locked in place.  Cones shown below:


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