Main cap girdles re-discussed

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gagembassett

gagembassett

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I was just rereading a thread I commented on a long while ago about main cap girdles and the ending consensus was a no..... HOWEVER I did read it and it seemed to me that everyone was only implying it to 2 bolt main girdles on an LA factory block. Now I do understand that some people still run 4 bolt caps and leave the outer bolts unused just to help transfer the stress across a more broad surface area. So my question is what does everyone think about running 4 bolt caps for that and adding a girdle on top? Yay? Nay? Why?
 
There is a David Vizard video about Ford blocks but they discuss the reason the main girdle is used on those. I suspect it would apply to the Mopar blocks as well based on the description, so I think I am now coming around to the idea of the girdle. Pay attention to the details in the video and see what you think.

 
On high horse power engines, you clearly see main cap and bearing "walk" witness marks upon tear down. That's the whole reason for a girdle. To eliminate that. Imagine if the caps are walking what that's doing to the bolts or studs. Sooner or later.......On the small blocks it might not add as much strength, but on the big blocks, especially with their deep skirted blocks, it adds a good bit. Imagine one with the main girdle AND cross bolted mains added, like the Hemi.
 
47 years of running big and small block Mopars and I haven’t found a need for one yet. My buddy that died last year and a well named Mopar engine builder and tried everything. Once a stock block get to a certain horsepower it’s gonna crack sooner or later. No matter what you do to it.
 
I can't see the benefit of a girdle in a small block, or a big block for that matter. My advice would be to buy a quality main stud set.
 
justinp61 said:
I can't see the benefit of a girdle in a small block, or a big block for that matter. My advice would be to buy a quality main stud set.
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Or if you are going to be in this sport a long time an afternoon block. They will handle more than what most of us throw at it. I’m wasting my Keith Black block as it’s been sitting since 2010 and has only gone 8.40@160mph. My last stock big block lasted 275 passes running 8.60’s before the block cracked. That may or seem like a lot but to some guys that would be a lifetime of racing. Where is the breaking point on LA stock blocks I haven’t found it yet. But then again mine is only in the 9.30’s area.
 
And that was the plan for me ARP studs, billet 4 bolt main caps, windage tray and possibly the girdle on my factory 360 block.
 
pittsburghracer said:
Please don’t drill a stock block for 4 bolt caps. You are weakening the block.
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No no I do know that, I won't do that. Just the extra outer surface of the 4 bolt cap to help with the high horsepower (600) and the high rpm (7,500) I won't drill the block for it
 
A stiff front and mid plate added to mount the engine securely to the chassis. Using the chassis to help eliminate block flex is the best on a LA block. Mount ears on these blocks create stress. Did you ever wonder why 340-360 blocks have a narrower mount on the left side?

Watch a sprint car come off a turn. If you would use mount ears on a mopar sprint car the block it would destroy itself. Many race blocks don't have mount ears. Using both front plates and mid plates help eliminate flex. Most high torque cars use the chassis to stiffen the block.

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600hp, waste of money and time putting a girdle on a SB mopar.

SB ford OEM blocks were NEVER designed for 1000hp and cut themselves in half no matter what bandaid is put on them. Try that 1000hp with a production based mopar, get the same results, broken blocks. Only a matter of time.

Girdles on a SB mopar do nothing to stop the issues of the block breaking or cap walk.

Want peace of mind, buy a better block if you can find one.
 
I know nothing about smallblock mopars.
I CAN see a benefit to a girdle on a big block Mopar or FE Ford, with the deep skirted block. Assuming proper machine work and good studs (most girdles use studs, quality is the question) I don't see how properly tying everything together with all that extra metal can possibly be a bad thing, or useless effort.
 
Read this... https://www.hughesengines.com/TechArticles/2mainbearingstudgirdles04232007.php

Looks like if you're gonna be pushing 600+ HP a main girdle and studs is a good idea but 4-bolt main caps won't do much of anything whether the extra outer bolts are used or not.

crackedback said:
600hp, waste of money and time putting a girdle on a SB mopar.

SB ford OEM blocks were NEVER designed for 1000hp and cut themselves in half no matter what bandaid is put on them. Try that 1000hp with a production based mopar, get the same results, broken blocks. Only a matter of time.

Girdles on a SB mopar do nothing to stop the issues of the block breaking or cap walk.

Want peace of mind, buy a better block if you can find one.
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Do they really not work though? When the engine is running each cap gets side-loaded individually so having them tied together allows the other 4 to support each cap as it gets hit with loading from the crank. That's my theoretical view on it anyway. The Jeep 4.0L I-6 got a main cap girdle added in to reduce NVH and works much the same as an SB Mopar one, granted it's not for strength but if it didn't work to distribute the side-loading between the main caps the Chrysler engineers wouldn't have bothered.
 
MopaR&D said:
Do they really not work though? When the engine is running each cap gets side-loaded individually so having them tied together allows the other 4 to support each cap as it gets hit with loading from the crank. That's my theoretical view on it anyway. The Jeep 4.0L I-6 got a main cap girdle added in to reduce NVH and works much the same as an SB Mopar one, granted it's not for strength but if it didn't work to distribute the side-loading between the main caps the Chrysler engineers wouldn't have bothered.
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Hooking a tuning fork to the main studs is what you are doing on a SB. It doesn't stop or alleviate cap walk. Does the girdle, positively engage with the cap? You tying the 4 sets of mains together at the end of the stud. Doesn't do squat on a SB as 33imp laid out.

600hp needs nothing but either good bolts and preferably main studs.
 
I look at it this way we kinda warn guys what we have seen over many many years of racing and if they feel happy putting junk it I mean a bandaid on their engine go for it. What’s 350.00 plus dollars today. I have some semi dry swampland with a nice view for sale in the Everglades. Lol
 
crackedback said:
Hooking a tuning fork to the main studs is what you are doing on a SB. It doesn't stop or alleviate cap walk. Does the girdle, positively engage with the cap? You tying the 4 sets of mains together at the end of the stud. Doesn't do squat on a SB as 33imp laid out.

600hp needs nothing but either good bolts and preferably main studs.
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Good point, I looked at the pics of the Hughes girdle and it is indeed attached to the ends of the studs and doesn't sit directly on top of the caps themselves. The Jeep 4.0L one iirc does sit directly on the caps.
 
pittsburghracer said:
I look at it this way we kinda warn guys what we have seen over many many years of racing and if they feel happy putting junk it I mean a bandaid on their engine go for it. What’s 350.00 plus dollars today. I have some semi dry swampland with a nice view for sale in the Everglades. Lol
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I can understand what you're saying. That's why I come here. Why waste my time when I can get multiple pieces of input from people that have seen or done it over the years. Rather than be like half my generation of new mopar guys that think they know it all. I listen to reason (most of the times at least lol) and that's usually due to budget. I hate cobbling stuff together, I try to do stuff as right as possible the first time so I don't have to go back and fix it.
 
crackedback said:
Hooking a tuning fork to the main studs is what you are doing on a SB. It doesn't stop or alleviate cap walk. Does the girdle, positively engage with the cap? You tying the 4 sets of mains together at the end of the stud. Doesn't do squat on a SB as 33imp laid out.

600hp needs nothing but either good bolts and preferably main studs.
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So you think that just a set of good billet caps with good ARP studs will be just fine for 600? Admittedly this is the first time I've ever shot for the moon like this. It's a learning curve but I'm determined to do it and do it as correctly as possible the first time. Learn properly on this one so the lesser builds down the line seem like a breeze. If that makes sense?
 
gagembassett said:
So you think that just a set of good billet caps with good ARP studs will be just fine for 600? Admittedly this is the first time I've ever shot for the moon like this. It's a learning curve but I'm determined to do it and do it as correctly as possible the first time. Learn properly on this one so the lesser builds down the line seem like a breeze. If that makes sense?
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I’m not sure where I am horsepower wise but you can take a good guess. My old engine ran 5.98 in the 1/8 and 9.38@138mph in the 1/4. With a solid lifter cam and an 850 carb it was totally out of steam before the 1000 foot line. My current stock block, stock main caps with studs has gone 5.98 too. I’m almost positive it had some 9.20’s in it or very low 9.30’s@140mph. This thing it pulling hard at the 1/8 now with a .660 roller cam and 1000 cfm carb. So far so good knock on wood.
 
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