4340 Crank, Steel Caps, Girdles . . .
- Thread starter Spongebob
- Start date
It's my understanding, that the purpose of the steel caps and/or girdle, was to prevent the block and journals from warping under the load. it made the crank the weak link. Withe the addition of the newer cranks w/o the caps and/or girdle, it will put the stress back on the block. 
ESP Products
Banned
- Joined
- Feb 27, 2002
We are building a similar engine right now. Internal balanced crank, stock rods, JE pistons, #3 cap, and an ESP Engine Girdle. The load pushes the crank down, regardless of what crank is in there. The steel billet caps will not crack or break like the factory, but the studs are still the only thing holding the crank/cap in place. To install a "good" rotating assembly into an engine without a girdle would be a potential waste of money. The girdle is designed to eliminate "cap walk" and save the crank.
Hope this helps.
Hope this helps.
Mike Licht
I was here first
- Joined
- May 23, 2001
I am sure some folks will disagree but the major cause of cap failure IMO is crank twist. This exerts funny loads on the caps and make them move around. If you have ever seen bearings that were worn on one side but not the other, that is caused by crank twist. AFAIAC the crank in more important than a girdle. Paging Dan from DLS..........?
Mike
Mike
Mike Licht said:
Kind of what I was thinking...crank flex/twist was what I thought to be the origin. Past experience with a 22 lb gundrilled SBC crank in a Super Stock application yielded similiar headaches.
I was hoping some of the guys with billet cranks would offer their 2 cents.
ESP Products
Banned
- Joined
- Feb 27, 2002
I'm sure major loads of power and torque do amazing things to all the engine components. In my experience I have seen #3 caps broken in engine that drove into our shop. I've seen higher HP engine that, when taken apart, showed the signs of "cap walk". That "cap walk" is when the cap hops up and down as the engine load tries to plant the crank in the asphalt. The engine girdle keeps the crank in place. I'm NOT saying the crank doesn't twist, but I believe the flex of the crank during the "cap walk" is a wider/more common cause of failure. Reason?! From the engine work we have done over the last 14-15 years building Turbo Buick engine we have seen many cases of "cap walk" [mostly in the past few years, as more power is produced with stock components] than crank twist. If you read between the line of what Mike and I are saying.... We, you, us, are making more power than the stock components can handle.... .... it's time to upgrade.
Hope this helps.
Hope this helps.
