Does a girdle in a BB Mopar help?

I've seen this touched on in a few other threads so I figured I would give the subject its own thread.

I've seen comments on both sides of the fence but is there any definitive proof that they add strength to the bottom end of a stock block?

No, you aren't going to find any proof, just a lot of opinions. The closest thing to proof is that Mopar engineering used a cross bolt design for HD applications.

All I’m going to say is ….. I’ve been 9.0’s at 3500lbs .070 jet in a plate , another plate with .073 on top of that . Stock block , stock main caps with studs …. That’s it !

Spray and pray . Don’t be scared !

IF I was using a stock block still , I’d put alum main caps , use a vacuum pump , aluminum rods and make damn sure the straps showed very little heat . Conservative timing and keeping oil out of the chambers will go a long way to keeping the engine out of detonation .
Just my opinion and what has worked for me

A flowed nitrous kit also helps a lot , the tech help
You get helps a ton . Everything that keeps the engine happy keeps it alive . Granted the block can only handle so much , but pay attention to all the things that make it more prone to break and hopefully you can make it live . My opinion no reason you can’t make 800 to even 1000 with good tuning and attention to details

We run a lot of them with girdles. We believe they help. I can say, I don't see how they can't hurt. Think about it, you stud the main caps and the tie them into a girdle that bolts to the oil pan rail. How can it not help? We have been running over 800hp with this setup for years. Bearings usually look really good when we do check ups. Only time they don't is usually with a repaired crank or where we have had other issues.

Do the caps show evidence of moving ? My stock block showed a lot of movement (no girdle stock caps with just studs )

I I don't know about a big block. But I can tell you on my small block the main bearings looked 100% better on tear down after the girdle than they used to.

I used to see the outer 1/3 of the main bearing right down to the copper, opposite of the deck.

Meaning the block was flexing all over the place on the power stroke.

Now that has been greatly minimized since the girdle

Small block 360, 1/2 fill, 800hp+. But same principal.

Yes...We still see some cap walk. We usually do an off season check, and we will generally see some light cap walk. We do race all these, and we run the timing near or at the max they will take.

consider a girdle insurance. is it going to help you make power? not really but if you cant keep your bottom end together it wont matter either. and yes we do see alot less cap walk with our girdle kits, after market cross bolted mains dont work. we've even made a girdle kit for a JP1 hemi that was a cross bolted main block. still had cap walk before the girdle. now if your only tying the studs into the girdle you wont get much benefit as the caps will still flex and walk around.

yes, i have proof... when i launched a rod in high gear at over 140mph, the girdle stopped it from swinging through my oil pan, didnt lose a drop of oil , didnt drive through any

My thoughts, I would tie it into the pan rail not just bolt it on (is there a pan gasket between?) dowels or sleeves of some type. Also some type of notch on top of all main caps so when bolted down it’s captive to the caps and pan rail. After this is done torqued down and line honed.i think that would be a tight non-flexing bottom end.

I always believed a girdle prevents flag poling of main studs, which causes blocks to crack from reverberation. I had cap walk in my 472, running too 6800, 10.60 @ 126. I swapped in a girdle and aluminum caps, never saw it again. Engine ran to 7k once it got better heads. For $400 and no machining, even if its minimal I'd think it's money well spent.

We stud the oil pan when we run a girdle...I think it helps the most.

Cross bolting the mains does basically NOTHING for cap walk. Been there seen that many times. Yet many believe it is the be all end all. There are other remedies for this and IMO a center counter weighted crank is your friend. As far as girdles go what can it hurt, especially combined with aluminum caps, lite bobweight and conservative on the timing. Do all that and I believe a stock block, provided the cylinder walls are good can last a good long happy life.

It does not hurt anything - the thicker the better - but I agree a good set of billet aluminum main caps with good studs everywhere along with a lightweight assembly like 2100 grams or below will go along way in reducing cap walk! the other factor is timing and a solid tune - too lean can be mean to the bottom end!

No, not in my opinion. I have not seen one on the market worth messing with. If you want to see girdles that work. Check out the girdles they run on diesels.

Mine did not Rod cut right though that girdle

Wow...Look at the bolt hole where it was bolted to the main cap, its all stretched out....Damn.

Late great Monte Smith had probably tried about everything before there was race blocks available. His opinion, based on experience, was that only thing that really helps stock factory big blocks, is aluminum main caps. He had had no help from girdles. I kind of trust his opinion.

Me too on the main studs and aluminum main caps now that we can't buy the Mopar Ductile iron main caps anymore

iagree up Me too on the main studs and aluminum main caps now that we can't buy the Mopar Ductile iron main caps anymore whiney

Cab.......are you saying you prefer the iron over aluminum caps if available?

So... what brand & type of rod managed to blow a hole through your block?

I can't recall who posted this pic previously (ccdave?), but this is the same basic setup my next block has to work with: standard aluminum main caps + "budget" girdle

I think everyone agrees all of these approaches are simply Band-Aids with various degrees of benefit on an OEM block. I'd LOVE a BMP aluminum block, but that's not even on my radar.

I agree, and I pasted my answer for n another thread


Weighing in on the girdle thing with my experience.
In 2003 I dynoed a megablock 4.15 stroke 4.50 bore 528 cube motor. Made 847 hp injected on methanol . I noticed cap walk on a crossbolted megablock, Max rpm was 7400. Bob weight 2432. I put a girdle on it. Didn't take away the cap walk issue. During this time we found a minor cracking the crank by #6.
I bought a rather expensive center weighted crank from Crower and took the girdle off. The C. W. Crank eliminated about 90 percent of the cap walk. I finally needed a little cleanup and align hone in 2019.
So IMHO the girdle basically can force a large portion of any movement into a vertical motion, which may help a little. BUT THERE IS NO TRIANGULATION to stop that vertical stress completely. So end result? IMHO they may be of some benefit, but not enough for a lot of stressfully builds.
Properly done, an add on girdle would be 3 inch or more tall, or thick, if that is how you would view it. That would require a rather short oil pan, like a dragster 10 qt . The big deal about it being so tall is it would now be so rigid it could transfer stress to the pan rails in all directions, not just lateral.

Years ago I remember TRENDZ posting a picture of the modifications he did to a stock block. If I remember right he machined the tops of stock caps flat and then made tool steel straps that went over the top of the stock main caps. It looked super slick and if I remember right he was well over 1000 hp with a stock block.

If I end up having to redo the motor in my Fury but am too broke to buy an aftermarket block, I'll probably turn it into a 512 and use aluminum caps, not bothering with the girdle.

[quote=VernMotor

Mine did not Rod cut right though that girdle
[/quote]

What did you attribute the rod failure to?

Yes
Based on the ductile iron material expansion rate at difference operating temps being very near the block cast grey iron rate
I've used both with no failures yet
I'm sure my current S/P 400 block E85 bracket stroker motor will have a major failure first run next year I sincerely hope not

Ouch........don't say that that's the set up i'm running on the bottom end been there sense 06

I agree, unless you are running a class that rules say you must use a stock block why would you? If you are trying to make 800+ horses buy a good iron or alloy aftermarket block. All the stock stuff is at least 40yrs old.
They are going to fail. Factory stuff was good but not for ultra high horsepower. Plus you have to hack them all up to get a decent stroker crank and aluminum rods to clear. Block is the foundation for a reliable build. Not a place to save money IMO
Pops

$5200 for a new block is out of a lot of people's price range.

In much the same fashion people buy $250.00 LS motors, turbo them, and go get another block when that one $hits the bed, It's cheaper to gamble with a stock block.

I used the 3/8" girdle by chenoweth back in yr 2000 to 2006 for 250 runs with iron caps,arp studs 14# of boost.I feel it did a glod job of helping things.

Eagle H beam

What did you attribute the rod failure to? [/quote]

Rod did not fail until the cy-wall crack..I believe it was too thin.. did't get sonic tested .. they all do now !!

And I will add that is that last Engine I ran with motor mounts.. Got a motor plate after that..

The weakness in aftermarket girdles is lack of height. Newer motors have deep sidewalls to tie into, adding a huge amount of stability up and down.

Rod did not fail until the cy-wall crack..I believe it was too thin.. did't get sonic tested .. they all do now !!

And I will add that is that last Engine I ran with motor mounts.. Got a motor plate after that.. [/quote]


what kind of motor mounts ? solids ?
if solids were used, do you think a rubber mount on the passenger side, or both rubber mounts used with a limiter would have prevented the block cracking ?

That's why modern serious performance engines have bed plates instead of main caps.

Hey, it's only money, right?

what kind of motor mounts ? solids ?
if solids were used, do you think a rubber mount on the passenger side, or both rubber mounts used with a limiter would have prevented the block cracking ?


[/quote]

Solid motor mounts with a limiter. block I had in the car before this crack a cy wall. always #3 . so I did't take the chance anymore