Main cap walk/girdle ?

Redrock2000 · May 11, 2018

I was wondering at what point of hp or rpm have y'all actually seen main cap walk? Having built a few Ford big block gas engines I've saw main cap walk more associated with higher rpm and using even main studs increases main walk let alone a girdle doing anything but holding the broken parts together or at best absorbing harmonics. I know the differences in diesel and gas but Ive saw high compression 460 based 2 bolt main engines revving passed 6500 rpm on a regular basis making 800 hp or more with stock main bolts and 0 cap walk. The mains of a 7.3 block are twice what a 4 bolt big block are. Why the concern with cap walk with a 7.3 and at what point ? Thanks

Arisley · May 11, 2018

A high compression gas engine would be a pretty low compression diesel engine. Not even considering throwing in 60 lbs. of boost of so.

Redrock2000 · May 11, 2018

So the higher cylinder pressure is the issue but at what point hp wise do you start to see cap walk? A 600 hp 7.3 doesn't see 60 psi of boost.

DieselJpower · May 11, 2018

Redrock2000 said:
A 600 hp 7.3 doesn't see 60 psi of boost.

Mine does

ja_cain · May 11, 2018

You kind of need to stop thinking about it in terms of horspower. Instead you need to look at torque as an adjunct to cylinder pressure. Torque is going to directly correlate to cylinder pressures. Where as hp is a function of both torque and rpm.

Sent from my SM-G930V using Tapatalk

m j · May 11, 2018

fretting is not uncommon in diesel engines at stock power

Redrock2000 · May 11, 2018

m j said:
fretting is not uncommon in diesel engines at stock power

That's something. How well do girdles prevent cap walk/fretting? My plan is to finish up my truck temporarily with a used forged engine while I build my original engine with Manley rods, block fill etc. My plan is to run 250/200 injector, either the up and coming KC s369 drop in or a T4 setup with a s467. And maybe some spray after while.

Redrock2000 · May 11, 2018

DieselJpower said:
Mine does

Sorry didn't mean to sound like a know it all.

ford_trck · May 11, 2018

I can make mine walk with a 6 speed and I'm only 400 HP. 4 high 3rd gear off the redline will shear a rib off the serpentine belt every time.

Redrock2000 · May 12, 2018

ford_trck said:
I can make mine walk with a 6 speed and I'm only 400 HP. 4 high 3rd gear off the redline will shear a rib off the serpentine belt every time.

Wow I guess I am way off comparing to a gas motor. But how well does a girdle help?r

ja_cain · May 13, 2018

Too bad you can't modify the block for splayed main caps. That along with some type of girdle qould probably be a pretty solid setup.

Sent from my SM-G930V using Tapatalk

m j · May 13, 2018

personally, even though I bought a girdle, I dont think they do anything.
IMO the block fill does more to help then a girdle.

Magnum PD · May 13, 2018

I’ll agree with that ^. Bedplate is far and beyond a girdle. Block fill for flex.

Redrock2000 · May 16, 2018

Thanks for the info y'all. I planned on doing a block fill but need to find a description on it that will upload pics. Anyone know of any?

m j · May 16, 2018

http://powerstrokearmy.com/forums/showthread.php?t=47572&highlight=fill&page=2

mine are at the end of that thread

Magnum PD · May 16, 2018

For the record, I tow some and hadn’t had a problem yet with getting hot. But I don’t have a full fill. Just partial fill.

DocBar · May 21, 2018

I've been running a high hp build for about 8-9 years with a girdle in it. I had no issues at all with main walk with a girdle. A cracked oil cooler and a wrist pin keeper, along with poor mechanic work, are the things that killed my truck. 1st time I've ever heard of a wrist pin keeper coming out and fragging a cylinder.