Thread: Crankshaft .060 oversize - is it good idea?

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I have .060 oversize rod and main bearings, and rusty crankshaft (2pc rear main seal).
Is it good idea to do that oversize or should I try to find new crankshaft in better shape? I'm going to put it in stock 350 engine for street using. The trouble is that I'm away from Unated States - from Russia, and I must wait a long time if I will order nominal crankshaft and bearings froms Summit, for example.
The second trouble is - here I can't do dynamic balance (it's possible, but it's VERY expencive - device for V8 engines is very rare).
May be the best way is order new nominal crankshaft - I think, it's balanced after production?
If no, give me a link for example, where I may find crankshaft ready to assembly "out of the box".

*excuise my poor English

Well for one thing your crank won't be .060 oversized it would be .060 undersize And I wouldn't use one that far out...I would say your idea of Summitracing.com or Jeg.com would be a good economic place to go.. You get the rod and main bearing when you buy the crank

Good Luck

At .060 under its still bigger than earlier 283/327 cranks---if you have the bearings use it--balance won't be an issue if using the original rods/pistons

thanks for your opinions, mates!

I'm right that all crankshafts are balanced after production?

Originally Posted by wbud

thanks for your opinions, mates!

I'm right that all crankshafts are balanced after production?

Yes, a production crank is balanced as a unit using "target bobweights" which will be close to what you'll have. When we talk of having the engine "balanced" today we're talking about the dynamic balance, where the actual rods & pistons being used have been assigned positions on the crank, and the precise weight of each assembly is considered in the "bobweight" for each journal before spinning the crank in the balancing machine. That's why Jerry says the balance won't be an issue if using the original rods/pistons. There are lots of magazine & tech articles on the web that explain the balancing process, and why things are done the way they are.

While the engines where in the test stand being run tested,we used to pin the harmonic balancers with wt's.I did that as apart of the test cycle when I worked at a Chevy engine plant.The thing was the factory tolerances where pretty wide and guys used to re-balance their engines to get a better balance job.
You said the engine is pretty rusty..060 is about as much I would want to go under.(actually I am used to cranks measuring either .010/.010 or .020/.020.The thought being a concern for it being cut beyond the hardness of the crank)If you could post some pictures of the crank,it would give us a better idea of the condition of your crank so we could best advise you from there.

It's crankshaft was undersized .020 but rest for years it the wet barn , then owner gave it to me - unfortunately, I have no choice to order new chank (it's about 50 days of waiting), in my local workshop they told me that they may do the biggest undersize, I found .060 oversize bearings and I thought that this repair possible.

take a strip of sanding paper and polish off the rust and then measure----I doubt that its rusted .040 !!!!!!!!!

Why does it take 50 days??????????


Aren't you close to Helsinki Finland?

Just to be sure.Are we talking the same measurement standards??.

yes-yes! I mean measurement in inches.
I checked - crankshaft was undersized to .020, then rusted and in my local workshop grinded\polished to about .040 (but a little bit more in fact). So if have .060 bearing, is it normal to use this type of repair? I mean, if bearings with this size exists, it's ok to use it on stock engine?

Delivery takes ~50 days due to shipping, preparing of Custom papers etc. Spares like crankshaft are very heavy, and it's a not a cheap delivery. Yeah, Finland is near my city, but I call shops - they have only 1pc rms crankshaft, I need to order new crank there - so, it's the same time and money if I'll order from summit. Yeah, it's Russian reality))))

Here’s a piece of useless, but interesting, information that I gained while working at the Flint V8 engine plant in Flint, Michigan starting in the 60s. In the olden days, I’m not sure when things changed, probably in the 70s or 80s, a crankshaft that was ground up to .009 undersize was OK for production. We had .009 under bearings that were used on the assembly line on a regular basis. Cranks .010 under or smaller were scrapped. This was for both mains and rod bearings, I believe.
Our boring machines for the cylinders couldn’t hold tolerance for bore size (a few thousandths over or under was common) so pistons were made in different sizes to fit the bores. These pistons were assigned a “letter” size and the bore size “letter" was stamped on the oil pan rail next to the corresponding cylinder, or rod bearing as these blocks were assembled at this point with the oil pan rail up. Those were the days when a 100,000 mile engine was a rare thing.
I’ve seen camshafts with undersize bearings spray welded (a process where molten metal was sprayed onto a red hot bearing journal) then reground and used for production.
Oversize rods (both big and small end) were copper plated and re-honed to attain proper size.

hmmm, food for thought

for stock use you will be fine at 060 the backer is thicker so it is just not more babbit so they do not beat out in use. many times i will try to find a better crank but in you case used what you have Male makes the bearings in cb633p for rods and mains ms909p and come with a over size flanged . on many job like this i would grind crank to housing bore with bearing s installed for real size then grind crank for oil clearance you want

Morning Pat---any snow??????????

I was just looking up the bearing numbers in 060 , you beat me to it---little sleepy yet, daylight saving time!!!!!!!!!!

Originally Posted by jerry clayton

Morning Pat---any snow??????????

I was just looking up the bearing numbers in 060 , you beat me to it---little sleepy yet, daylight saving time!!!!!!!!!!

hey jerry not much snow .wet and mud yep the Male/clevite book shows 060 evey one makes them and i think King or ACL go bit more on some engine then other s so many 350s out there they like to keep them cranks in service longer. for guys for in the states were getting a good 350 cranks that can be truned less then 30/30 like falling off a stump. we had a old steel crank in a bbc i did not want to throw it out or pay to get it welded so it was ground to the max guys that race it did not have any money . i could not grind it any more.so it would get the Hi spots belted off . use check it with both eyes shut block and crank came out of a scrap yard $40.for the454 block $25 for the454 steel crank . she is still working thats been over 20 years one of the best 468 i ever had