I have a cast eagle crank that is being ground 40 over. Believe its 2.00 now instead of 2.01. The person who is turning the crank said that he grinds eagle cranks 40 over for people who run the circle track cars (8-9k rpms for a couple hours straight)..

Is there anything I should or possibly be worried about? My car has LE2 heads/cam so it should be around 460-470 flywheel hp. Forged Pistons and rods. Spins to 6550rpms. Driven 2 days a week on average. Sees the drag strip maybe twice a year but I get on it some about everytime i drive it..

 

Is there anyother reason than he likes to do it? might need a timing set made to take up the diffrence. if it was not chewed up this is a stupid thing to do

 

i would not use a crank that is ground that much in a performance car at all, especially since the price of that crank. NEW is not much more than the price of machining the old crank

 

Just on the mains? Both rod and main? BTW - it's called grinding 40 UNDER.

Smaller journals help at sustained high RPM's due to bearing speed, but for a daily driver I would never use a crank past .020" under, and I can't remember the last time that was. Performance applications can reuse the crank several times with just a polish or go .010" under with the right bearings and maintenace schedule. For racing, once the crank is ready to hit .020" under, it's time to change it out anyways...plus I'm talking forged cranks mostly, .040" under on a cast piece is nuts..

 

you could put it together and try it, the latest rage in NASCAR engines is using HONDA size bearings with a smaller bottom end rod, all for lighter internal weight.

 

I never knew they made bearings for .040 under?!!

 

I have had .060 under bearings for chevys, and also the HONDA size setups, have much reduced frictional drag, PLUS! and Im not sure, but I have heard that the genuine honda bearing has a proprietary shape to the bearing,whats that about!!

 

True - but they change out cranks like they do socks.

 

[QUOTE=ronbros]you could put it together and try it, the latest rage in NASCAR engines is using HONDA size bearings with a smaller bottom end rod, all for lighter internal weight.[/QU

Actually most are using Quad-4 or Eagle sized now (1.770")

 

[QUOTE=nosfed]NASCAR guys are also running BILLET cranks,not a cast crank.
I have snatched the complete rod throw out of a GM steel comp crank,by off turning it to 2.000 from 2.100. The rods were not hurt the crank broke on both sides of the rod pin and came out the block. Cheap stroker-- Uh HUH

 

like I said put together and try it!! real hiperformance engines dont last forever a
nyway, but if you are going to putter around the street, then a stock engine should do OK. also I have cut steel cranks that spun a bearing to under size only to have them break in half, find out later that cracks developed internally that could not be detected by magnafluxing. anyway its not like were talking his crank is expensive.

 

It's a bit foolish to put it together and risk $3000.00 when a new crank cost less than $200.00,Don't ya think.

 

Amen to that. Not making much sense to me.

Rich

 

K kewl just making sure. Buying a new one

 

Actualy, if you had a forged 4340 crank, you can turn it way down, but you have to have it re-nitrided. Same goes for a Cast steel crank. In a street car .040 under is no big deal. As long as the rotating assembly is ballanced, and the motor is blueprinted. you will have no problem, and bal./BP is a must on any high performance engine you want to stay together for any length of time.