6.5 Girdle

[JeepSJ]

I am a big fan of roller rockers. There is a lot of friction (heat, HP loss...) where those suckers ride on those shafts.

[Slim shady]

More Power,I sent you a PM with my cell number. I am interested in the girdle if I can afford it. i like his work, still brings tears to my eyes. I did make it my screen saver and my background picture. Dam I like good machine work.

Slim

[More Power]

Your message has been forwarded...

Jim

[gophergunner]

looking for a little clarification here........i'm thinking that the girdle is just extra support or strength for your crank bearings to prevent the typical cracking on the block....am i right? sorry if it sounds stupid but i just wasn't positive and was hoping for an answer

I'm also wondering if its better to have the girdle or the splayed main caps.......i'd rather not take it to the machine shop because i'm not planning on doing a full rebuild just yet.

also curious if something like the girdle is easy to install, and are they rather readily available?

if adding the girdle is a good way to ensure i don't crack my block i'm thinking i should do it while i have the engine out of my truck.

thanks in advance for any advice

[MaxPF]

My instincts tell me the girdle is plenty adequate.

I had an epiphany when I was working on my build. I dropped the crank in the block and was staring at it when the cause of block failures occured to me.

When the cylinder in any engine fires around TDC the stress put on the crank is not torsional, as many people think (that happens many degrees of rotation later), but rather a bending moment. LAter in the rotation there is a combined torsiona and bending moment. These bending moments flex the crank in the main bearing supports, and tend to push the caps back and forth along the axis of the main bearing bore. This, combined with the spreading force put on the main cap block threads from the bolts and the limited thread engagement of the outer holes, is what I believe initiates cracks in this region.

A sturdy girdle (preferably much heavier than the one DSG sells, but the DSG girdle is far better than no girdle) ties the caps together, and minimizes movement in the axis parallel to the crank bore. In theory this should drastically reduce the stress on the main webs. Since the caps won't move as much the crank's bending moment will also be reduced in magnitude, and this should (again, theoretically) reduce fatigue stress in the crank. Using studs in place of main bolts to get full thread engagement and reduce the spreading force on the bolt holes is also a big help. This is how I am building my 6.2, and I think these steps will pretty much solve the block and crank issues that these motors are known for.

[HammerWerf]

MP:

Any pictures of the Jesel Roller Rockers available to post?

I recall the Grape was experimenting with some Mopar Roller Rockers.

HammerWerf

[More Power]

I just wish I had Andrew's machining skills... .

Jim