2 bolt versus 4 bolt main
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
So true!I do a lot of tight-budget builds, and it just doesn't take much to really go off-track. It's why I always hammer a budget right out of the gate - I run into so many situations where the goals and the budget just aren't initially aligned and it takes a lot of work to hammer out the gap. I remember a tight budget build where I suggested the owner keep his existing tin (pan, timing cover, etc.) but he wanted "new"...so he bought new Milodon stuff and then whined about the $300
Owner: "I want 500HP!"
Me: "OK, figure on around 10K"
Owner: "Um...what can I get for around $4K?"
Last edited by billla; Nov 30, 2011 at 01:42 PM.
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
So this is probably a dumb question, but why do the studs make the mains stronger, I mean if it were just the material, ARP makes bolts as well as studs right, but i don't figure that its just the material. Can you get a main gurdle for gm blocks? I would figure that once you get 7500 to 8000$ into a build you wouldn't want to see that money go to waste.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Studs don't make the mains stronger - the caps are what they are. But they do apply more clamping force which increases the load that the caps can carry before they walk. Same for 4 bolts over two, splayed outer bolts, steel caps, etc. Once the bore distorts, the bearing is going to fail more quickly.
This is also why switching from bolts to studs requires an align-hone - the bore is no longer round due to the increased clamping load, and that needs to be corrected.
This is also why switching from bolts to studs requires an align-hone - the bore is no longer round due to the increased clamping load, and that needs to be corrected.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
News to me, Boss 302/351 were 4bolters. 351/429 CJs were 4bolters. 427HP was crossbolted. Seems to me if high RPM is in the cards I would go 4bolt but, would'nt spend the $$ for a cap conversion on a 2 bolt block (speaking from expirience here as I have spent time on a Bridgeport doing this job, if the shop has a CNC blockmaster maybe it would be less grief but, it is a true PITA to do this job.) If your building a hydraulic cammed motor with regular heads, I wouldn't worry about 4bolt mains.
Drifting
Joined: Jun 2010
Posts: 1,781
Likes: 15
From: Oxford Ohio
Windsor Two bolt The FEs other than the side oiler are two bolt. Not news anymore. The splayed cap conversion is an easy one takes an hour or so plus the Align hone or bore. Setting up for the align hone $80.
Racer
Joined: Oct 2006
Posts: 435
Likes: 18
From: Florida
So this is probably a dumb question, but why do the studs make the mains stronger, I mean if it were just the material, ARP makes bolts as well as studs right, but i don't figure that its just the material. Can you get a main gurdle for gm blocks? I would figure that once you get 7500 to 8000$ into a build you wouldn't want to see that money go to waste.
Drifting
Joined: Aug 2004
Posts: 1,883
Likes: 124
From: Lubbock TX
Studs are SAE threads into the block and fine threads on top. Torque readings are much more accurate since you're stretching the bolt less with every nut flat on the fine threads. You also preserve the threads in the block for future rebuilds, there's no friction between the stud and the block, just "grab", they're not pulling and turning at the same time, that's happening between the stud and nut.
As for the crossbolts on the LS engines, it's a whole lot more than holding the crank securely due to extra bolts. This design actually incorporates the cap as part of the block's structure, making the entire bottom end much, much stiffer and more stable.
As for the crossbolts on the LS engines, it's a whole lot more than holding the crank securely due to extra bolts. This design actually incorporates the cap as part of the block's structure, making the entire bottom end much, much stiffer and more stable.
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Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
There is one more thing, A bolt has threads all the way while the stud is threaded only on each end with an unthreaded part in the middle making them stronger. Someone must have missed that when they googled it 
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
I went out to the shop and pulled out a used ARP bolt from a project that just came in, and it wasn't fully threaded, either...
Last edited by billla; Dec 1, 2011 at 12:52 PM.
Le Mans Master
Joined: Jan 2006
Posts: 6,506
Likes: 139
From: Butler Pa
I would take that article with a huge grain of salt, or maybe a whole salt lick I don't know the guy so I have no idea what his credibility is or sources are, but I sure wouldn't run a 950HP, 8,500 RPM stock GEN I block! There are just too many (comparatively) dirt cheap aftermarket blocks to even think about it. At that build level, we're talking about a $25K+ engine...$1500 or so for an aftermarket block is a very small part of that overall cost.
I don't know the guy so I have no idea what his credibility is or sources are, but I sure wouldn't run a 950HP, 8,500 RPM stock GEN I block! There are just too many (comparatively) dirt cheap aftermarket blocks to even think about it. At that build level, we're talking about a $25K+ engine...$1500 or so for an aftermarket block is a very small part of that overall cost.
I remember about 30 years ago reading an article about a 9000 rpm, 900 hp stock block motor that was being successfully campaigned. It was then stated at the end of the article that this was probably the limit for these blocks.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Just to clarify, the bolts relies on the threads that thread all the way in to the block pulling on the blocks threads while the studs are threaded on both ends resulting in more clamping force. A head or main bolt with threads all the way from head to the end would snap before you got it to torque spec. Anyway I was going to get into it but I have better things to do, must be getting soft in my old age 
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
They already have a number of circle-track crate engines. 
http://media.gm.com/content/media/us.../1201_lsx_454r
Safety Car
Joined: Jan 2009
Posts: 3,736
Likes: 56
From: anchorage ak
So does any one make a main gurdle for gm blocks, if such a thing exists. I remember seeing something along that line years back but don't remember who or for what.
Last edited by bluedawg; Dec 1, 2011 at 01:33 PM. Reason: Can't spell worth a damn.
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
Press release from today - it's moving that direction They already have a number of circle-track crate engines.
http://media.gm.com/content/media/us.../1201_lsx_454r
They already have a number of circle-track crate engines. http://media.gm.com/content/media/us.../1201_lsx_454r
I wonder how much you have to shell out for this motor ?
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
It's in the press release - $23,200K...which honestly ain't bad.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
But they are available for aftermarket caps.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
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From: Oxford MA-----You just lost the game!!!!
Press release from today - it's moving that direction They already have a number of circle-track crate engines.
http://media.gm.com/content/media/us.../1201_lsx_454r
They already have a number of circle-track crate engines. http://media.gm.com/content/media/us.../1201_lsx_454r
Scott
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
But we digress - sorry
Last edited by billla; Dec 1, 2011 at 11:45 PM.