is this guy legit? 2-bolt mains stronger than factory 4 bolts? - Page 2 - Hot Rod Forum : Hotrodders Bulletin Board -- Hot Rod Forum

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  #16 (permalink)  
Old 08-09-2019, 09:46 AM
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Originally Posted by rivvgs View Post
so I have been told, I have read and been told by my machinist. that the 4 bolt blocks of the 2 piece main seal era where the largest portion of 4 bolt block originate. often have more core shift issues.when over boring a cyl core shift can greatly effect the thickness that is safe to bore. I am not sure why but the latter blocks tend to have less issues

Casting techniques have changed a lot. Cores are formed around hard foam patterns that are not removed prior to the pour so there isn't a disturbance of the core for pattern removal anymore. Castings are done with higher head pressures which improves distribution, lessens pits and holes, increases density. The process is highly automated which is more consistent than humans doing this hot and dangerous work. My maternal grandfather worked as a overhead crane operator at Jones and Laughlin, as a young man he got me in for a tour, that and me working in a slaughter house, packing, mechanic, truck driver and candy making companies over my summers and holidays really raised my GPA in school. Which brings me to taxpayers covering college tuition; sitting around with my buddies the subject of what did you do on class breaks came up; "anybody go to Cancun?". The answer was everybody either caught up on studies and/or worked to make money. So when I see hordes of vacationing students on TV, I'm not too inclined to pour more tax dollars into free college for these folks because they borrowed their way through school. Trading your time for debt is a life lesson the young need to learn.


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Old 08-25-2019, 09:58 AM
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He is full of crap on a lot of issues.

First, we need to delineate what "strength" we're talking about. There is a big difference between how strong the main webbing is and how much power it can handle without deforming/exploding.

Many of the 2-bolt blocks had additional webbing, which means the webbing is stronger, but there are only two bolts holding the main caps in place. Depending on the casting, the general (very general) accepted guideline is that in order of weakest to strongest it goes A) 2-bolt, B) 4-bolt, C) a 2-bolt block machined for 4-bolt.
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Old 08-26-2019, 08:53 AM
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Out of the Archives we had this discussion:
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Old 08-29-2019, 08:59 AM
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I remember scuttlebutt about some 4 bolt OEM blocks being as strong as their 2bolt siblings. This seemed to be centered around the 400SBC. The 400 block of choice was the 2 bolt around these parts, and then some were converted to aftermarket 4bolt (Splayed caps). Perhaps theres a grain of truth here but theres a lot of 'correlation does not equal causation' going on in that 'article'.

The EPA came down hard about NVH, and drove the OEMs to beat on transfercase designers about 20yrs ago. We saw a big shift in chains/sprockets vs gears, modernized casting designs and materials. Additionally, the luxury '4wd' segment pushed the goalposts out even farther, cuz God knows Biff and Buffy need bank-vault quietude, and push-button 4wd rollin through Beverly Hills in their 3-ton Dreadnought Class SUV
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