O.K my engine has 2 bolt mains and i would estimate it around 350hp. i would like 400-425 which i think i can achieve with intake alluminum heads and another cam if needed.I have been looking at crate engines because of this block. Is 400-425hp under 6K revs reliable with two bolt main caps. I am capable of bolting the heads and intake on and probably the cam swap.I have heard of modifying the main caps but for the labor i would have to ay for a teardown and the heads and such i could just buy a crate engine.

people have done it. Just make sure you use studs on the main caps instead of the stock bolts

Check out this thread

http://www.chevelles.com/forums/showthread.php?t=38173

Studs don't make the caps any stronger as they are stiil a cast caps the flex.

[This message has been edited by CNC BLOCKS (edited July 09, 2005).]

2 bolt should be fine for that rating. If you want you can put studs with a girdle but 400 give or take should not be an issue as long as your bolts or studs are a good quality...ARP comes to mind. Anything past the 450 mark would warrant more strength of course

[This message has been edited by mike73z (edited July 09, 2005).]

Save your money 2 bolt is fine till you start pushing 500 and even then a two bolt block modifyed for splayed 4 bolt caps is stronger than a 4 bolt so don't bother getting a 4 bolt block.

------------------
Jamie
'75 LT
Man Don't ypu hate it when the car's engine is back together and you gotta wait on the hood!

<font face="Arial,Verdana" size="2">Originally posted by becnjam:
Save your money 2 bolt is fine till you start pushing 500 and even then a two bolt block modifyed for splayed 4 bolt caps is stronger than a 4 bolt so don't bother getting a 4 bolt block.

</font>

This is a pic of a 4 bolt main cap in 2 peices and this engine made 415 on the dyno and lasted one season and GM rates there 4 bolt blocks at 350 horse and to say a 2 bolt block is good for 500 horse, As an engine builder I would not consider a 2 bolt main for 500 horse application as I have seen many broken main caps over the 29 years in building performance engines and on 2 bolt block over 300 horse the bearings never look good as the caps are flexing and seem to be loose in the registers.

http://i7.photobucket.com/albums/y276/CNCBLOCKS/brokencap.jpg

Is that an oil pump gear thats broken in half?

<font face="Arial,Verdana" size="2">Originally posted by tomsti:
Is that an oil pump gear thats broken in half?</font>

Yes thats a oil pump gear. I have to disagree. Yea maybe that motot blew but I have seen and have many friends that have 450 hp Small blocks 1 is a 4 bolt the other 2 have 2 bolt 383s. they have been beating them up for a few years now. Dont seem to have any problems

quote:
--------------------------------------------------------------------------------
Originally posted by tomsti:
Is that an oil pump gear thats broken in half?
--------------------------------------------------------------------------------

Yes thats a oil pump gear. I have to disagree. Yea maybe that motot blew but I have seen and have many friends that have 450 hp Small blocks 1 is a 4 bolt the other 2 have 2 bolt 383s. they have been beating them up for a few years now. Dont seem to have any problems.
======================================

The oil pump gear is not from that engine but is showing that powder metal gears that Melling performance is using are not as good as the old steel gears.

As and engine builder and 29 years of building engines we don't use 2 bolt mains in anything that would be over 300 horse as we dyno about every engine we build an I would not want to put a 100% laod on a 500 horse engine using a 2 bolt mains and on those 383 2 bolts I'm sure the main bearings if taken apart would not look as good if compared to a good 4 bolt block using at least the 2482 center caps.

We are machining a block for Kings Crankshaft Co. as one of his customers broke 2 main caps and the engine is only 480 horse. (circle track)

Here is a pic of the block that we are sending Rick King.
http://i7.photobucket.com/albums/y276/CNCBLOCKS/SPLAYEDCAPS020.jpg


[This message has been edited by CNC BLOCKS (edited July 10, 2005).]

[This message has been edited by CNC BLOCKS (edited July 10, 2005).]

The engine that had the broken main cap came in to be refreshened didn't even know the cap was broke till it was taken apart.

I know of a couple of 2bolt, stock main cap, sbc motors that have gone low 10's / high 9's in a 2700-3000 pound car (+-600HP) for a whole season. But usually when they go away they do it without descretion of how many components they take with them. I have to agree with CNC in 400-425HP is WAY beyond what the 2bolt configuration was ever intended for. Can it be done... not only 'can' it, but it is done all the time. Probably because most guys that think they have 400-425HP 'really' have somewhere around 350-375, and use &lt;20% of that 99% of the time on the street.

But it's your pocketbook! Just remember Mr Murphy is standing behind you twirling his magic wand of engine carnage and saying,, "go ahead, make my day" http://www.nastyz28.com/ubb/wink.gif

The car is a weekend cruiser not a race car. I would probably take it to the strip to see what it is capable of but that's about it. I guess i will save for the crate engine route.

According to the #'s i read this block could be 2 or 4 bolt.Here are the #'s incase i am wrong. front pad has T1109CKJ and 13R424056 and on the back behind dist has 3970014.Can these #'s tell if it is a 2 or 4. Thanks.

The ONLY way to tell if any block is 2bolt or 4bolt is to pull the pan and look for your self. Even in block numbers that were listed as being 4bolt only, some have slipped through the line in 2bolt configuration. Remember the main caps are just a machining process that happened LONG after the casting was complete and shelved.

<font face="Arial,Verdana" size="2">Originally posted by Marv Davis:
The ONLY way to tell if any block is 2bolt or 4bolt is to pull the pan and look for your self. Even in block numbers that were listed as being 4bolt only, some have slipped through the line in 2bolt configuration. Remember the main caps are just a machining process that happened LONG after the casting was complete and shelved.</font>


YES! Very similar to what I mentioned in the "Block Castings" thread on the hi-per engine board. Just because there is a casting number, does not mean that it's 100% for sure. We switched compatible cores due to necessity to keep the line running.


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Pic of My Camaro Z28 (http://members.aol.com/justbugg/camaro.jpg)

Southern72... Why would you want to save for a crate just 'cause' your core is a 2 bolt.

I fully understand what CNC is saying and I respect his opinions, but look at the pic he posted.

Is that my eyes or is that a 4 bolt main cap????

The crate engines you buy may be 4 bolt main, but the weakest part of the main is still the same as in any stock 2 or 4 bolt engine. The main cap!!!!

The cap in CNC's pic would have broke just the same if it was a 2 bolt. No diff.

I say go with your plans and put on the heads and cam swap and have fun.

Alot of this "2 bolt vs 4 bolt", and cap strenght debates scares people out of building what they want, and spending more money for something just about like what you would build..

Yes a 4 bolt is stronger, but is a 4 bolt stock any stronger than a 2 bolt stock??? IMHO no. Both still has the weak bolts that pull on the block's threads, both still has the same metal caps, both still has the same bolt angles. Heck IMO stock 4 bolt blocks in some cases are weaker than 2 bolt blocks cause of the angle and placement of the outter bolts.

And the stuff CNC and others are talking about are full race engines. CNC said that him self.. (dirt track)

Those engines are pushed to the limits at all time. Built with alot more power, and turned to alot higher RPM, for alot longer.

When are you ever gonna run a weekend, street, street/strip, cruzer car at 7,000 rpm for an hour or 2 hours straight?????

<font face="Arial,Verdana" size="2">
Yes a 4 bolt is stronger, but is a 4 bolt stock any stronger than a 2 bolt stock??? IMHO no. Both still has the weak bolts that pull on the block's threads, both still has the same metal caps, both still has the same bolt angles. Heck IMO stock 4 bolt blocks in some cases are weaker than 2 bolt blocks cause of the angle and placement of the outter bolts.

[/B]</font>

The problem with 350 2 bolt blocks is there is not enough surface area of the cap in the register and they tend to flex alot more compare a 400 2 bolt the cap is the same width as a four bolt cap and has more surface area and does not flex as much as the tiny 350 two bolt cap as we have seen the block registers messed up do to the caps moving around and do to the caps moving the bearings never look good either.

I have been building racing engines and machining blocks for 29 years now I should know what works and what doesn't.

Any 2 bolt block over 350 horse is a time bomb with a lit fuse. (trust me)

So by their own addmission, those that say they have witnessed a 2-bolt get destroyed was in race cars.

Not that I have that much knowledge in the subject but I would guess the demands on a street motor and a race motor would be slightly different. If your not going to race it alot I wouldn't worry about it.

I have a 2-bolt with 340+HP and am adding AFR heads and a 100 shot of nitrous...I would be extremely surprised to see the mains go before something else(but I just race it once every 2-3 weeks).

------------------
81 Z-28 355 Home Ported World S/R Heads(1.94/1.5) XS268 solid cam (230/236@.050, .477/.488 Net Lift), 650@ DP, Tremec TKO 5-speed, 3.42s, Nitto Drag Radials. 13.4@102.9 w/ 1.95 60ft time.

there is a lot of good information in this post. I beleive that we have have missed the boat here. 300 400 450hp is not the real killer. Its the RPM that really kill the engine. A 2 bolt main will not hold up as well as a 4 bolt above the 5000 rpm range. Build the 2 bolt, keep it real with respect to rpm and you will be happy. (in your street car) If your going to the track step up and build a 4 bolt motor.

Well, I have been running a studded "weak" 2 bolt 207 block in my camaro for a year now in road racing. No problem, and it makes over 350hp/450ftlbs at the rear wheels. Its also running a low boost turbo system on pump gas. It never sees 6000rpm because it peaks at 5200rpm.

I have seen many 2 bolt main engines running over 400hp in circle track with no issues. I think that it is an RPM instead of a HP problem. HP loads increase linearly. RPM loads increase geometrically. My engine builder will happlily build a circle track engine to run over 400hp on a 2 bolt main block if RPM is limited to 6000rpm. Any higher and he wants to see a 4 bolt block to keep the main caps from moving.

Let me weigh in on this as an engineer, not as a master engine builder. There are many,
many things I don't know about building engines, but about bolted joints I have some
experience.

The bolts or studs themselves should be considered very stiff springs, and the block and main cap can be visualized as if they are made of rubber. They deflect in very similar ways; they're just stiffer. 2-bolt blocks are slightly stiffer in the webs than four-bolt blocks simply because they have a few less holes drilled in them, however the difference is not measureable, and based on failure data, not significantly weaker- other areas experience fracture failures far earlier, so it is correct to conclude there are other areas stressed significantly more. An iron 4-bolt main cap doesn't have additional material strength than a two bolt cap as they're made from the same material. To gain additional strength, they would have to contain additional bulk in the stressed areas or be composed of different materials. Of course, this is news to nobody. Adding two extra bolts unquestioningly increases the stiffness of the bolted joint and reduces the crankshaft induced fatigue on the fasteners. This will provide some additional support for the cap, so if the cap is experiencing deflection in the bolts and suffers additional stresses because the bolts are not keeping the caps firmly against the block, then four bolts will help distribute the load more effectively. This will help in a situation where you have somewhat elevated crankshaft forces for extended periods of time- such as
when towing or hauling heavy loads. However, for short term periods of greatly increased stresses, the incremental increase in support may not be sufficient to contain these stresses because the additional bolts and associated bosses on the main caps can be too far away from the stresses to handle the loads generated in the bearings, resulting in exactly the fracture shown here. This is the kind of fracture you'll see if you have nitrous, detonation, or very high engine output and suddenly gain traction causing the bearing forces to skyrocket instantaneously.

Steel caps addresses this very effectively by providing a much stronger material.

Splayed outer bolts are kind of a mixed bag- the benefits are that the forces in the block are more effectively distributed. However, forces in the caps are also distributed, while forces from the crankshaft remain concentrated- so, when you distribute the clamping forces while the forces to be opposed remain concentrated, the result can be deflection of the main cap. Fortunately, the material strength is capable of handling this added factor as well. The other problem with splayed main caps is that it is impossible to use studs which, through increased stiffness are quite effective at distributing clamping loads on the threads more evenly than bolts. Bolts also cut into the precious soft grey iron threads in the block upon every installation/removal, so for racing the splayed caps can result in very little additional clamping force capabiltiy in the outer bolts because repeated installation/removal dimishes the ability of the outer threads to engage the fastener. So, the splayed main cap bolts have a less than possible purchase on the block material.

As for whether HP or torque creates forces in bearings, the answer is both. The only vibration attibutable to HP are vibration, while the only (significant) forces attributable to piston/rod/crankshaft dynamics are attributable to torque. RPM does not increase main cap stresses in a balanced engine. This is intuitive, if an assembly is balanced one must only support the weight of the rotating mass- such as a flywheel. Spinning the flywheel doesn't make it heavier or induce loads on the supports. If the engine is out of balance, this is not true. Thus, bearing loads generated by torque are not increased just because the torque is generated at a speed higher than zero.


If each throw of your crankshaft is not balanced, the answer is more complicated. It is possible to have out-of-balance forces offset by cylinder pressures, however the effectiveness of this would be different at each RPM. This is used in generators that always operate at fixed speeds, but the wide RPM range of vehicle engines make this impossible. So, forces that are added to torque induced forces may increase or increase bearing (and cap) loads depending on where the excess mass is located. If the counterweight is too heavy, it will somewhat offset combustion forces, if it's too light it will increase them.

[This message has been edited by Douglas Staley (edited July 13, 2005).]

<font face="Arial,Verdana" size="2">Originally posted by Douglas Staley:

The other problem with splayed main caps is that it is impossible to use studs .</font>


You may want to look at this block with splayed caps as it does have studs installed as these caps are 3/16 of an inch taller then the stock caps you must use studs and these caps are 7.500 wide and when installed actually sfiffen up the bottom end as the pull on the pan rail instead of just the main webbing.

Also as I have said before we dyno about every engine we build and the dyno puts a 100% load which can't be duplicated in a drag or street performance engine.

We probably machined about 60 blocks last year for splayed caps and with splayed caps and a front billet cap and a strap on the rear main cap we rate those blocks up to 580 horse.

If you compare the Chevy 2 bolt cap to those used in the Ford and Mopar engines the chevy caps are very small compared to the Ford and Mopar as they have bigger registers they sit in and are quite a bit wider and more stable.

The key word in our shop is DEPENABILTY and we feel to build a 400 plus horse engine cost alot of money and the customers we have all know that a 2 bolt block is not what they want to start with unless its going to machined for splayed caps.

Again the block in this pic does have studs.
http://i7.photobucket.com/albums/y276/CNCBLOCKS/SPLAYEDCAPS020.jpg

When I saw that split cap, the first thought that came to mind was detonation.

Just as important as 2 vs 4 bolt in keeping things together in the cap area are; component weight,balance-static and dynamic,indexing,windage,clearance,cap and block finish and alignment,studs (which arent necessarily stronger, just better at holding a clamping force owing to the fine threads).

Regardless of all that you can still break a bottom end quick with detonation, as evidenced by the broken cap in the earlier pics.

I personally watched a 63 chevy 11 traverse the quarter in a tunnel rammed heavily nitroused 2 bolt(but studded) 350 in 8.54 seconds. It did it over and over all weekend.

I am not saying that a 2 bolt is better or a 4 bolt is better, but I am saying in most instances it has more to do with other problems when a cap failure is encountered than just 2 bolt vs. 4 bolt.

It is generally accepted that the 4 bolt chevy block is the one to use for street and mild race performance applications, however, I would not hesitate to use a 2 bolt block if that is all I could get.

In serious racing applications, I would say that at some point, the cap material/attachment would be a limiting factor, but at those levels and applications anything less than an aftermarket block & billet cap/studs combo is probably a bad idea anyway, and any kind of endurance racing would be especially hard on stock blocks and caps.

My answer to the original question is yes.

Well again this is not a race car. i go to some car shows and might engage with a riceburner from a redlight or two on the weekends but that's about it. i might put the heads and intake on and later i can always buy a 383 shortblock.

<font face="Arial,Verdana" size="2">Originally posted by 70CitrusZ:
When I saw that split cap, the first thought that came to mind was detonation.
</font>

The broken cap was not from detonaion as we machined the block and supplied all the parts for that engine from water pump to flywheel and the customer assembled it them selves we fit the rings, bearings and degreed the cam in for them. And I dynoed and tunned the engine for them as this engine had a 38 pound crank lite weight everthing.

Like I said before we had no idea when the cap broke as it was discover during a rebuild and the pistons and rod bearings showed no signs of detonation and even all the main bearings looked good we replaced the center caps with with billet 4 bolt repalcement caps. This engine has won many championships in its day and know is going to be used in a street rod.

GM rates that block at 350 horses at 5700 RPM and this engine turned up to 7200 and made 415 horse and was raced every weekend.

I would say GM wasn't far off on the horse power rating.

I stand corrected, you can use studs on main caps with splayed bolts- but you can't stud the splayed outer bolts. Your picture does show studs on the inner positions but bolts on the outer positions, if my eyes aren't deceiving me. You could screw studs into the outer positions by hand after putting the caps in place, and then add the nuts, but you can't permenantly mount studs in the splayed outer bolt positions unless you never intend to remove them again! That said, otherwise I think my point stands...

<font face="Arial,Verdana" size="2">Originally posted by Douglas Staley:
I stand corrected, you can use studs on main caps with splayed bolts- but you can't stud the splayed outer bolts. Your picture does show studs on the inner positions but bolts on the outer positions, if my eyes aren't deceiving me. You could screw studs into the outer positions by hand after putting the caps in place, and then add the nuts, but you can't permenantly mount studs in the splayed outer bolt positions unless you never intend to remove them again! That said, otherwise I think my point stands...</font>

Douglas

I hate to burst your bubble but this is a pic of a Brodix block and the center splayed caps use studs on the outer holes as this block came from Brodix this way.
http://i7.photobucket.com/albums/y276/CNCBLOCKS/blowerengine015.jpg

Wow, how do you get the caps off with the splayed studs in place?

CNC- Where in the NorthEast are you located? I'd be interested in your prices if you are around upstate Ny(building a motor this winter)

2 bolt is good to 500 HP, so you're safe http://www.nastyz28.com/ubb/wink.gif

<font face="Arial,Verdana" size="2">Originally posted by Douglas Staley:
Wow, how do you get the caps off with the splayed studs in place?</font>

Doug

The outter studs have a bullet nose design as not to bottom out the threads and we use an allen wrench to get them out and install them as this engine we see every 2 years for a rebuild and the studs come out fine.

<font face="Arial,Verdana" size="2">Originally posted by AllGoNoShow:
CNC- Where in the NorthEast are you located? I'd be interested in your prices if you are around upstate Ny(building a motor this winter)</font>

We are in Maine and the CNC shop is 1 hour from the New Hampshire line and about 5 minutes from Portland International Airport and the engine shop is about 20 minutes for the CNC shop.

<font face="Arial,Verdana" size="2">Originally posted by 1978LT:
2 bolt is good to 500 HP, so you're safe http://www.nastyz28.com/ubb/wink.gif</font>

If your talking a Big Block Chevy there should be no problem but if your talking a 350 small block I can tell you have no performance machine to build racing engines and test them you may want to call some real high machine shops and tell them you want them to build a 500 horse engine and they have to use a stock 2 bolt main block I think they would hang up on you.

Over the last 29 years I have dealt with lot of machine shops all over the country and I know that any one building a 500 horse engine in NOT using a stock block with 2 bolt caps as we would be scared to put that on the dyno and put a 100% load to it. Again DEPENDABILTY is the key word here.

And if GM rates ther 4 bolt block at 350 horse then a 2 bolt is rated even more HP. I think your reading to many Hot Rod magazines.

If some one is going to build a true 500 engine W/O nitrous it cost a lot of money to do that and they sure and hell aren't going to use a stock block that has 2 bolt caps on it.

I will send this post to some of the shops I deal with I'm sure they will get a good laugh out of this one.

Thanks for the laugh

<font face="Arial,Verdana" size="2">Originally posted by 1978LT:
2 bolt is good to 500 HP, so you're safe http://www.nastyz28.com/ubb/wink.gif</font>

Take the time and read this link as there is some good factual info there.

http://www.chevelles.com/forums/showthread.php?t=38173

CNC BLOCKS-Yes I was referring to BBC. I know better than to assemble a 2 bolt 500 HP SBC http://www.nastyz28.com/ubb/wink.gif

CNC blocks....

Got any aftermarket used 4.125" bore or bigger SBC blocks sitting around?



------------------
'81 Viper Blue Z-28
383 Stroker
11.33 @ 119.9 N/A
10.18 @ 133.8 N20

<font face="Arial,Verdana" size="2">Originally posted by Stroked-Z:
CNC blocks....

Got any aftermarket used 4.125" bore or bigger SBC blocks sitting around?

</font>

The only blocks I have is a brand new Dart Liitle-M with billet caps 350 mains and its still the box it came in and I also have a brand new Bow-tie block with 2 bolt caps and that is still in the crate.

I think I have an old cup block but its 4.185 and has a dry sump rear main cap on it.

well...how much power can an 2 bolt BBC handle?

CNC-The 5.0 Ford crowd around here gets away with 2 bolt mains. How?? I know for a fact my buddy just had his dynoed (stock block, rods, pistons, 11 psi supercharger) and it consistently put out 425 to the WHEELS. Are Ford main caps sturdier or does he have a time bomb waiting to explode? http://www.nastyz28.com/ubb/wink.gif

I appreciate your insight on the subject of blocks. And again I would NEVER build a true 500 HP 2 bolt Chevy, or any other small block for that matter! I'm perfectly content with 300-350 HP with a 2 bolter http://www.nastyz28.com/ubb/wink.gif

<font face="Arial,Verdana" size="2">Originally posted by 1978LT:

CNC-The 5.0 Ford crowd around here gets away with 2 bolt mains. How?? I know for a fact my buddy just had his dynoed (stock block, rods, pistons, 11 psi supercharger) and it consistently put out 425 to the WHEELS. Are Ford main caps sturdier or does he have a time bomb waiting to explode? http://www.nastyz28.com/ubb/wink.gif

I appreciate your insight on the subject of blocks. And again I would NEVER build a true 500 HP 2 bolt Chevy, or any other small block for that matter! I'm perfectly content with 300-350 HP with a 2 bolter http://www.nastyz28.com/ubb/wink.gif</font>

Read this as I have already ansered this in referance to the Ford and Mopar 2 bolt caps in this thread.


If you compare the Chevy 2 bolt cap to those used in the Ford and Mopar engines the chevy caps are very small compared to the Ford and Mopar as they have bigger registers they sit in and are quite a bit wider and more stable.




[This message has been edited by CNC BLOCKS (edited July 15, 2005).]

<font face="Arial,Verdana" size="2">Originally posted by CNC BLOCKS:
Read this as I have already ansered this in referance to the Ford and Mopar 2 bolt caps in this thread.


If you compare the Chevy 2 bolt cap to those used in the Ford and Mopar engines the chevy caps are very small compared to the Ford and Mopar as they have bigger registers they sit in and are quite a bit wider and more stable.


[This message has been edited by CNC BLOCKS (edited July 15, 2005).]</font>

That's what I thought. I just never had a Ford and a Chevy apart at the same time to compare. Thanks man!