2 or 4 bolt block

[chip46wis]

This is one of my favorite controversies-----2vs 4 bolt--just a quick true story from some time ago.A friend known as Mr big block around here built a 481 in. BB 2 bolt 12.5 compression ect ect and put it in a 69 camaro,I wont tell you the shift rpms as most wont believe me-but it was over 7000 He ran this car street and strip for 5 years with NO problems---

[arkracing]

Originally Posted by Mudder67

This is all good to hear. My 2 bolt 383 stroker is being assembled this week. It's getting studs.

No worries mate.

[gator2511]

I ran a two bolt block in my vette for years. Strip and street racing, 440 hp. Never a problem.

[bigjimzlll]

Detonation is what kills....It will kill a 2 bolt or 4 bolt cap. although the 4 bolt may live a little longer. I've seen blocks/caps that ehen pulled apart look as if they were welded. The caps move and actually transfer metal from the cap to the block and vis versa.
Which ever block you use, use a quality fastner and make sure the caps fit good in the register. align hone/bore the caps and balance the assembly.

[FUNMUDDER]

IMO, the 2 vs. 4 bolt is the same idea as buying tools. If you can buy the socket set you want for 60 bucks, 1/4 3/8 and 1/2 in with ratchets and extensions, but you can buy the hole kit with wrenches and screwdrivers and so on for 85, you fork over more money for the better item. Thats just my way of thinking, it may not be right though. For the little amount more of money, id get a 4-bolt.

[chevman-67]

This is a good topic!!! Now from expierence I have ran both blocks never had 1 better than the other!! I have spun alot of bearings in both!I just blew a set of bearings in my 4 bolt block with no more damage than my 2 bolts that I have blown.1 block is no better than the next for ANY TYPE OF STREET USE WE WILL EVER SEE THAT IS LEGAL FOR STREET.Therefore YES they are the same price for a new core if you want 1 buy it.

[71400lb]

Uh oh!
My truck has a 400 SBC 4 bolt main(original motor was a 350)...it's basically stock, 4 barrel Quadrajet, it has a towing cam(Comp Cam)and dual exhaust...it's been rebuilt(bored .30 over) and the previous owner(guy who rebuilt the engine)said it's putting out about 325 horsepower.

He also told me the engine came out of a 72 Nova, but I can't find any records where a 400 SBC came in any 72 Nova's! Why would they put a 400 SBC 4 bolt main in a Nova anyway?

It has run perfectly in the year I've owned the truck, but
should I be worried about this engine?

Thanks,
71400LB
1971 Cheyenne 3/4 Ton 2wd
400 SBC/400 Turbo/3.73 Eaton/Open

[Tx Firefighter]

You fellows sure are getting worked up over this.

Let me tell you a little Tx Firefighter secret here....your local GM dealer is your best source of 4 bolt 350 blocks. See, those Goodwrench 350 engines are 4 bolt. If I look in the core pile and see a greasy engine with 350 Goodwrench stickers on the valve covers, I buy it. They charge 100 bucks for any small block core engine.

I get two or three a year that way. Never got a bad core yet either, just wore out.

[CHEVYE]

i've ran 2 and 4 bolts and have had no difference in the 2 whatsoever. whenever i have a 2 bolt done, i make sure that they stud the bottom end and i've never had trouble with one.

[pjmoreland]

What does it mean to stud the bottom end? Just curious.

[wolfthing2000]

Ark and Mudder, I am doing the same as you with a 383 build.

[wolfthing2000]

Studs and nuts for fasteners and not bolts

[bigjimzlll]

Originally Posted by 71400lb

It has run perfectly in the year I've owned the truck, but
should I be worried about this engine?

Thanks,
71400LB
1971 Cheyenne 3/4 Ton 2wd
400 SBC/400 Turbo/3.73 Eaton/Open

Do not worry. It will last a long time in a mostly stock configuration. Higher compression and more RPMs will hut them.

[pjmoreland]

Thanks wolfthing2000. That makes sense. I guess the studs can be run all the way into the hole to maximize thread engagement.

[wolfthing2000]

PJ, you are exactly right but do not overtorque the studs to the bottom because that could cause a crack. I believe they locktite the studs in and don't realy worry about torque on this end, just securing the stud.. The other end/ fastener end is fine thread, takes more torque and because the threads are spread out it holds better. ( I do not want to get into the exact science of this, just that fine thread torques better).. All in all if set up with good alloy hardware and not re-using old rod bolts etc. the 2-bolt set up is great.. Some have said that the outer bolts on the 4-bolt caps will work loose and then you are with a 2-bolt that has been weakened by not having the close proximity of cap retention, like a 2-bolt, adjacent to the 2 inward bolts. I think this is why the 400s of early 4-bolt caps were dropped and they went 2-bolt.

The true hardcore strength set up is 4-bolt splayed caps , where the bolts retain at an angle to the adjacent cap mounting surface pulling the outer edges of caps against there marting register and not being aligned with the downward force on the crankshaft. BUT this is for hard core motors remember and not for street engines.

How much horsepower and bottom end grunt do you need anyway?? Once the 400 HP 383 truck hooks up off the green light the vehicle beside you is now in your rear view mirror anyway!!! If he is ahead, let him win........he deserves it!!!,,,,,,,,,,,,,,,,,meanwhile just drive your truck and enjoy it.............we're not building dragsters for crying out loud!!

[wolfthing2000]

I do guess I deserve you an apology:::::::::::::::::::::::::: some of you might be building dragsters!!!!

Sorry guys!

[Brainchild]

2 Bolt mains are fine IMO,what they need is 4 bolt rods

[fastwillie 696969]

im going to go with a 6 bolt engine on my next project motor