Fevre

Have a 383 crank (3.75) that has about 500 miles on it but has gone through a couple bearing failures and now is just a touch under spec. Seems I have heard that with a cast crank you can weld the journal and regrind to spec. Anyone have experience with this?

The Money Pit

Get a firm price on the work before you commit.I was going to have a 350 crank turned and found I could get a new one for about $50.00 more.
Much better off getting a new crank if performance is what you have in mind.

mapman

If the cost of repair is 50% the cost of new, go with new.

Fevre

Seems I paid about $100 to have it reground the first time but I neglected to check the rods. The rod is out of round and needs resizing. I have a new 383 forged crank but wanted to put together the old parts I have and put that motor in my Formula. I want a lower the comp ratio than the pistons I have are rated at, 10/1, so I can build a supercharged 383 with the forged crank. I also have to take into consideration having a new crank balanced with the old parts which with ext balancing adds a few more $'s to the equation.

fauxrs

If material is welded onto the old crank and then ground to spec, what makes you think the balance is still good? buy a cast Scat or prowler crank for $180-$200 if you need a reliable new crank for fair price.

Unless you are trying to build a real screamer, a static balance of matching the weights of each rod assembly will work. it certainly isnt the preferred method, but is done all the time. In fact since your reciprocating componants are already balanced the crank balance may not be as big an issue.

The last crank I had this done too was over 15 years ago and even if I could remember what I paid it wouldnt apply now anyway. BTW that was for an odd-fire buick V6 that had rod knock for over a month before I diagnosed it correctly - rebuilt over one weekend with reground crank and new bearings.

Fevre

Better then not getting a new crank balanced with the existing rods/pistons. It really should be no diff than a typical regrinds except you weld a very thin amount on the journalthen grind it down to size. The last regrind took it down to .030 under and now it is about .035 in an oval shape. Believe .030 is max for Chevy specs. More wanted to know if this is an accepted practice. This will be low rev (<6000), low budget rebuild since I have all the componants.

Barry's70LT1

Why not have the the crank polished.
That combined with an already loose fit should allow you to use a .001 or .002 oversize bearing which should put you back in spec...

MotorHead

Not an expert on this ( or anything else for that matter ) but I think you can get the journals chromed or something like that to build them up, maybe someone else knows a little more about this.

vette_c5c6

I would go with a good used crank or better yet a new-one.

Fevre

Was reading a rebuild manual and found that you can go .040 under on the journals so looks like I got one more regrind left in it. :thumbs:

norvalwilhelm

I checked this morning with a very knowledgable Professor that specializes in this type of thing and he is very sceptacle. He doesn't recommend a cast crank and unless put on just right flacks off or if put on too aggressively affects the fatigue of the crank.
I would go for another crank.

dman535

Call DS Engines in Clawson - Ask for Mike. 248 583 9240

Top notch machine shop - they do a ton of hi po stuff, would be able to help you out.

http://www.dsengine.com/

Fevre

Thanks Norval, figured it would be optimal for performace, hoping to get one more regrind out of it.

Derrick

I'll check em out, :thumbs: .