Block girdles, yay or nay

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K.O. SWINGER

Meeting in the alley since 1976
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So let's face it opinions/facts are constantly changing on a lot of popular upgrades . Many preferred parts have been ridiculed over the years as no good junk subpar etc only to find out that in the right hands and combinations there as good as the new stuff sometimes even better. The last consensus that I heard on block girdles was save your money they don't really help for a small block Mopar, has that changed? do you use one or do you hate them and why.
 
They do nothing but add weight, cost and complexity. It’s no different that running a stud girdle on the junky GM stud mounted rocker system. I have dyno tested girdles and they will lose power because you are inducing flex to all the other studs.

Same thing with main girdles. If something is moving it will move whatever movement there is to another main. It’s a bad system.

If you can’t keep the main line in shape with what you have, buy a better block.
 
Here’s a picture of mine but I think I’m just a hair over 400 horsepower
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Hughes sells parts and machining services. Not surprising that they recommend them. I believe that the SBM uses 1/2" mains bolts and the competition are smaller? So maybe not as significant a need for reinforcement? I can see the potential for added stability but I have no idea at what HP level it would become needed. Is a 1/4" thick plate really strong enough? I bet you would be surprised how much deflection can be induced, even into the flat plane. I think if I went to the trouble, I'd be using thicker plate or something that had ribs for additional beam strength.
 
Hughes sells parts and machining services. Not surprising that they recommend them. I believe that the SBM uses 1/2" mains bolts and the competition are smaller? So maybe not as significant a need for reinforcement? I can see the potential for added stability but I have no idea at what HP level it would become needed. Is a 1/4" thick plate really strong enough? I bet you would be surprised how much deflection can be induced, even into the flat plane. I think if I went to the trouble, I'd be using thicker plate or something that had ribs for additional beam strength.
Yes I remember discussions about the way that the small block girdle is designed that is not as good as the big blockand I think it has to do with all points not attaching to each other.
 
Hughes sells parts and machining services. Not surprising that they recommend them. I believe that the SBM uses 1/2" mains bolts and the competition are smaller? So maybe not as significant a need for reinforcement? I can see the potential for added stability but I have no idea at what HP level it would become needed. Is a 1/4" thick plate really strong enough? I bet you would be surprised how much deflection can be induced, even into the flat plane. I think if I went to the trouble, I'd be using thicker plate or something that had ribs for additional beam strength.

Exactly. Look how thick the block and main webs are. 1/4" plate is about like reinforcing a Kevlar vest with a silk cover. Ain't gonna do a thing. At worst it's going to make things worse by interfering with the main bolts mating, and any load it tries to absorb will just be twisting on other caps, not the block.

Now, replace the main caps with one huge cast structure and it might do something. But it would also need a couple dozen fasteners to truly take up any load. I'd add dowel pins between every oil pan bolt and effectively make a "split block" with a 125lbs structural oil pan if I was trying to reduce flex. But then the oil pan bolts are pretty shallow, and not a lot of other places thick enough to take more bolts.

Plus, at that point, might as well fix the oil feed to the crank and rods too by feeding mains oil through that bottom structure.

Seems cheaper to just go with a big block swap, or an aftermarket block at that point though. The deep skirt on a BB does the same thing, even if it kills a bit of power due to oil control.
 
They do nothing but add weight, cost and complexity. It’s no different that running a stud girdle on the junky GM stud mounted rocker system. I have dyno tested girdles and they will lose power because you are inducing flex to all the other studs.

Same thing with main girdles. If something is moving it will move whatever movement there is to another main. It’s a bad system.

If you can’t keep the main line in shape with what you have, buy a better block.
None of that is true for a big block, though, since their girdles also incorporate the oil pan bolt perimeter. THAT actually adds strength.
 
I like the idea of a girdle for a big block, because it ties the main caps to each other, AND the pan rails, meaning the rest of the block.
I don't think a girdle is near as useful for a small block.
 
I had my machine shop install the Hughes girdle on a 360 engine I was building. The machine shop recommended one because they put them on all the small block Fords they build. So I bought it and had them machine the block and caps for it. When I picked the block up, the owner of the shop did not feel that it did much at all, and wasn't necessary. So in my application, my opinion is it isn't needed. I think a better main cap would be more beneficial than a girdle.
 
None of that is true for a big block, though, since their girdles also incorporate the oil pan bolt perimeter. THAT actually adds strength.


What I’ve seen is fractures in the pan bolt holes and out from there.

The pan bolts were never designed to carry a load like that. Neither were the pan rails themselves.
 
What I’ve seen is fractures in the pan bolt holes and out from there.

The pan bolts were never designed to carry a load like that. Neither were the pan rails themselves.
Never thought of that. Never seen it either....but that doesn't mean a dang thing. lol
 
I saw this on Facebook a while ago on mopar engines group on fake book and book marked it. One piece lower main cap assembly from 7075 aluminum. Is in or came from Brazil.


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Some of the ones I've seen are 1/2 inch plate, they are also used with beefier main caps. All this stuff has to be machined up together.
 
So let's face it opinions/facts are constantly changing on a lot of popular upgrades . Many preferred parts have been ridiculed over the years as no good junk subpar etc only to find out that in the right hands and combinations there as good as the new stuff sometimes even better. The last consensus that I heard on block girdles was save your money they don't really help for a small block Mopar, has that changed? do you use one or do you hate them and why.
Get a set of splayed 4 bolt main caps and your done. It would be awesome if you could get a 4 bolt cap for the front main bearing cap.
 
They do nothing but add weight, cost and complexity. It’s no different that running a stud girdle on the junky GM stud mounted rocker system. I have dyno tested girdles and they will lose power because you are inducing flex to all the other studs.

Same thing with main girdles. If something is moving it will move whatever movement there is to another main. It’s a bad system.

If you can’t keep the main line in shape with what you have, buy a better block.
FYI, the magnums have the same junky stud mounted rockers as the sbc, in fact you can use sbc rocker on a magnum head
 
FYI, the magnums have the same junky stud mounted rockers as the sbc, in fact you can use sbc rocker on a magnum head


Right. The magnum uses a junk rocker system. That’s what I said. Even the die hard GM idiots don’t use stud mounted rockers any more.

It’s sickening that Chrysler guys fawn over adapted GM garbage.
 
Right. The magnum uses a junk rocker system. That’s what I said. Even the die hard GM idiots don’t use stud mounted rockers any more.

It’s sickening that Chrysler guys fawn over adapted GM garbage.
I hear that. This is another reason that the magnum heads are not a budget head, unless you stay with the junk rocker arms
 
What makes you think a splayed cap is better? Another GM hold over throw back.
It doesn't have to be splayed. I can't believe that guys build their engines and don't have the block machined for 4 bolt mains. If all of the main caps were 4 bolt like the bbc then a stud girdle would be a benefit.
 
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