[CA70RS28]

Is it still okay to use a large journal sbc steel crankshaft if it's been machined .030 on the main and .040 on the rod journals?

[jaybee]

Yes and or maybe no. What is the horsepower level for this engine? Why was the crankshaft turned to that size, was it magnafluxed and passed? Do you know the history of this crankshaft, did it come from a abusive past such as a race engine?

[97Z4C]

i dont use any steel cranks turned over .030--there are alots of crank turners that try to turn that much off rod lournal to re locate center to get alittle more stroke--me personally i wouldnt advise using it -if you do use it , make sure its raduised and balanced assy. -chek deck height of pistons

[Greg O]

Interesting question...Ask a guy if it's ok to turn down a 400 crank main to a 350 main for a 383 and they'll say fine. Well, that is turning it down .20 which is way more than you are talking about on your crank. But guys, myself included, start getting spooked much over .020 on a crank. You can get a new crank for less than $200 if on a budget. I'd be inclined to do that. Like suggested above, if that thing was beat on bad enough to need .030/.040 to clean up, I'd shy away.

[ss27]

Rs 28 here is my comment on this one . I used to be in the machine shop bis for close to 40 yrs between working for my uncle then on my own.In that period of time we fixed everything from an Allis Chalmers to a Waukeshau pile driver engine and we had avery good reputation for top quality workmanship. If the crank was to be used in a passenger car driven by a grandpa or grandma i would say use it they are not car killers and dont do more than 50 or 60 mph.On the other hand if its to be used in a truck that works hard or anthing else subject to abuse musclecar street rod etc no more than .020 on either rod or main and i dont care if the crank was made of KRYPTONITE thick bearings have too much babbit on them and will pound out from compresion torsional load and high Rpm. Is this old school yes very old school but also very wise logic do it once the right way.Do you have to use a steel crank or just for bragging right,s a stock nodular cast chevy crank can take a lot of abuse ground chamfered and polished the right way. Look for a 10/10 cast crank use a stock z-28 pump the steel drive rod and you will be fine. Alex

[Busted Knuckles]

OK, large journal cranks are 2.45" and 2.10", mains and rods. What you're talking about is one with a mains turned down a whopping ONE PERCENT of it's original size and rods cut down by almost TWO PERCENT. If the turn is done right with a large radius at the filets, it's probably stronger than when new.
Clevite makes their bearings thicker by changing shells every .020 if bearing size. Standard and .010 under use one shell with different bearing thickness, .020 and .030 use the same shell, different bearing thickness, and so on.
If it's done right, run hell out of it. It's still a FORGED crank and unless it was absolutely hammered in a previous life, it should be fine.