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Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Hotrodding Basics> is this guy legit? 2-bolt mains stronger than factory 4 bolts?
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Thread: is this guy legit? 2-bolt mains stronger than factory 4 bolts? Reply to Thread
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Topic Review (Newest First)
08-29-2019 09:59 AM
AutoGear 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
08-26-2019 09:53 AM
JeffB28 Out of the Archives we had this discussion: https://www.hotrodders.com/forum/hec...ck-142976.html
08-25-2019 10:58 AM
curtis73 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.
08-09-2019 10:46 AM
BogiesAnnex1
Quote:
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.


Bogie
08-09-2019 08:17 AM
BigMo
Quote:
Originally Posted by joe_padavano View Post
But, but, it's on the interwebs so it MUST be true...
[emoji106]

Sent from my SM-G900V using Tapatalk
08-08-2019 08:14 PM
rivvgs although there are less compressive loads, and slower piston speeds. they never made a 4 bolt main 327. research the top OEM hp gen1 small block.many a 7500 rpm 327 roamed the streets
08-08-2019 08:08 PM
rivvgs
Quote:
Originally Posted by OC_ View Post
https://westcoastengines.com/2-vs-4-...into-the-myth/

To me, it seems like this guy is all over the place. He says the EPA was enforcing NVH standards. Thats BS, the epa doesn't care about noise vibration and harshness at all!

I think hes trying to say that out of SBC blocks manufactured in the 80's and 90's, the 2 bolt main ones are better.
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
08-05-2019 07:16 PM
64nailhead No


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08-03-2019 11:57 AM
Rip VW Ah it is a good life it is Mr Bogie. I am setting out on the porch just finished a small plate of Blueberry muffins followed up with a gallon of good Coffee. The sun is shining and there is a light breeze blowing and I can hear the ocean waves crashing on the shore..

Ahh as a good friend of mine used to say.. Tis a good life as long as you don't weaken!!
08-03-2019 11:24 AM
BogiesAnnex1 My wife is big on lean protein from fish, I prefer North Lake Tavern pizza and a pitcher of PBR. She and my cardiologist say this isn't good for me, but you know somtimes you have to feed your soul as well as your body.

I've been sitting here on the patio with my pittie, who is chasing horse chestnut seed pods falling into the yard, and a pot of coffeee while sneaking a Hostess cherry pie all morning while typing these responses. The summer sun is just peaking above the trees accross the street. I'll head for the shop pretty soon. Life is good.

Bogie
08-03-2019 08:02 AM
S10xGN Eating bacon is bad for you this week, but wait a month and it'll be the "latest and greatest" superfood.

Russ
08-03-2019 07:12 AM
ProStreetRob Through the decades there have been numerous articles on 10 bolt rears are better than 12 bolt, T350's are better than T400's, 2 bolt mains are better than 4 bolt, bla bla bla... Usually they come from people with 2 bolt engines, 10 bolt rears, and T350 Transmissions, LOL

There's Pro's & Con's on everything, which one is; smaller, lighter, quicker, stronger, cheaper to build, etc... Bottom line is if your making BIG POWER you want something that can hold it, and if your making low to moderate hp then you don't need the biggest & baddest. I make 649 RWHP (about 750HP at the crank) so I'll stick with my 9.9" Rear, Tremec TR6060, & 6 Bolt Mains Thank You
08-02-2019 11:58 PM
BogiesAnnex1 The EPA cares about external noise. The total is capped at so many db at some distance. Obviously everything is making noise but the big contributors are tires and exhaust. I don't see stiffening or strengthening the engine as having a big effect.


However, the motorcycle companies play pretty hard here so they can devote more of the db allocation to exhaust tone than rotating assembly and valve train rattle or gear whine. The Twin Cam and Milwaukee 8 Harley's have a fake timing cover who's purpose is to soak out cam drive noise leaving more space for exhaust noise. I fixed my Twin Cam so I transmit both cam gear whine and loud exhaust which I'm sure far exceed the EPA's miserly limits. But I'm deaf in one ear (exhaust side) and can't hardly hear with the other so with that counter balancer engine I need a lot of noise to hear if it's running.



Bogie
08-02-2019 10:37 PM
OC_
Quote:
Originally Posted by techinspector1 View Post
"He says the EPA was enforcing NVH standards. Thats BS, the epa doesn't care about noise vibration and harshness at all!"

If you'll do a search on the web, you'll find out differently.
.
I did. I didn’t find anything. Please show me what you found.
08-02-2019 07:38 PM
joe_padavano But, but, it's on the interwebs so it MUST be true...
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