turning a crank ?

what is the max i can have my stock crank turned. it is at 2.467 on number 3 and 7. the rest are 2.490. the bearings that were in it were obviously 010. so can you get 040 bearings or no. i havnt seen any.thanks

Your crank grinder MAY be able to get .040 bearings but....there may be little choice in brand or composition.

Nick myself I want run a crank turn more than .020 I had one turned .030 on the mains and rods.When the engine would get up to temp the crank would start flexing when I would get on it hard and oil pessure would go away and get a viberation. Could open the hood and rev it and see it in the crank pulley but when cold the woblble went away run smooth with no viberation at all until it heated up.This was on a 351w in a 86 Bronco.
my sister had I built her.

Jim

this engine only turns about 5200rpm or so. i see clevite makes some p rated 040 bearings. so i know i can get them now. i guess the question is should i have it turned this much for this application or just spend an extra hundred and buy another crank?. i know i will have to turn the other crank. the motor is around 300 hp i think.

69F100 wrote:Nick myself I want run a crank turn more than .020 I had one turned .030 on the mains and rods.When the engine would get up to temp the crank would start flexing when I would get on it hard and oil pessure would go away and get a viberation. Could open the hood and rev it and see it in the crank pulley but when cold the woblble went away run smooth with no viberation at all until it heated up.This was on a 351w in a 86 Bronco.
my sister had I built her.

Jim

I call BS


I ran a boss 302 .050 .050 turned it 10,000 rpm for years.... my first stroker was a 460 crank turned .150 offset to 4 inch and ran the F*$k out of it for years turning it 7500 rpm. never ever had a problem, must have been the machinest if you had problems..... the 460 crank journals are 2.50 dia.... I turned mine to 2.200..... the 351 w crank journals are 2.123 dia if my memory is correct and if it was a problem why don't chevy have problems they are 2.1 and even 2.0? Some ProStock engines are running 1.9 rod journals.......making 1500 hp

you had something other wrong than the crank wobbling from turning it down....... like wrong flywheel, out of balance rods, or wrong crank balancer....it was not the under cut on the crank... Period....


I want you to know I am not busting your balls just don't blame it on something it wasn't...


Randy

well i will send the crank in then and see what they say, thanks. something wasnt right with this because all the bearings were already wore thru to the copper after only maybe a total of 40 minutes of runtime. not sure what happened but hopefully i get it figured out.improper break in or too tight maybe.thanks guys. kyle r.

Randy call it Bs if you want I pulled the crank and replace it with a .010 .010 crank replaced crank and bearings only and never had another problem out of it.It might not have been because it was turned .030 might have just been a weak crank just I want have one and turned that much and run a crank turned that much anymore myself.That is all I was saying.

I should have put this in on the first It might not have been because it was turned .030 might have just been a weak crank the machine shop said when I carried it back it was weak but they are now out of bussiness

Sorry bronco thought I read bruno posted when I put Nick's name up need to pay better attention

X2 like Randy said on the machine work Guys. THE CRANK IS THE MOST IMPORTANT PART, IMO.
If it aint right, your screwed from the git.
Get with Adney, and get it all balanced. Then there will be no worries.
Regards.
Al

Like I said I was not busting your Balls.....

Now I have seen some cranks come with out of round journals.... so what I am saying is Probably your machinest messed up.....and it was not the undercut that messed it up....If you think on that mentality why are you not scared to bore your block over .010 or .020 ?


the Thing to do when you get a part back from the Machine shop............ Is double check all work.....Yourself..... that way you know it is right before you assemble it.....



Have a nice day
Randy

True Randy I double check everything now they did give me the .010 .010 crank and bearing.