I was looking at a 454 block today, i was talking to a old racer who used to race old nitro dragsters, he has a highly well regarded machine shop that does a lot of work on race engines. He said he dont think 4 bolt blocks are any better that 2 bolt and he believes a lot of this stuff about 2 bolts being no good is so the big companies can sell after market blocks. He said he wasn't sceared at all to make m***ive hp with a 2 bolt. You hard core racers out there school me, tell me what you think?
Kind of depends on your definition of "m***ive hp", but a 2 bolt big block Chevy will work fine for most applications.
I wouldn't say that 4-bolts are a conspiracy since they've been regarded as the racers choice since before aftermarket blocks where even really an option. Most cars probably don't really need em, but if you want to build a bullet proof motor you should have the sturdiest foundation you can get especial if you're planning on turning some R's (esspecial with a big block chevy). <O
I may have worded this wrong, i dont think he meant it was a conspiracy, i think he meant a lot of poeple will tell you 2 bolts are no good to sell 4 bolts. He also said before he would use a 4 bolt he would use a older model 2 bolt "and this i havn't checked on" and turn it into a 4 bolt using spayed main caps that the outside bolts angle in, but he would use the 2 before doing that, he felt like it would hold up just fine.
A 2 bolt block with splayed caps is stronger than a straight 4 bolt block. But like Squirrel said a plain 2 bolt block will tolerate most street applications.
Unless you are revving it into the outer stratosphere, the two bolt is fine. If you want to spend money, spend it on rods first. Four bolt caps and a forged crank are just money down the drain if your rods are junk.
If you take a 2 bolt block and put ARP studs in the mains you have the equivalent of a factory 4 bolt block. We've done this for years and in the case of the BBC we found that the earlier 2 bolt block made a little more horspower than the 4 bolt due to the core design of the 4 bolt was too m***ive in certain areas and caused bore distortion losing some compression when the heat was on. The later blocks didn't exhibit this to a great extent as internal cores were changed over the years to save iron (weight) and like anything else "practice makes perfect". Frank
When I worked at the machine shop we built our built proof 4 bolt blocks using 2 bolt blocks with after market caps. That was before you could buy all this trick stuff now. I ran a 468 for four years going through the traps at 7200 rpm on a junk 2 bolt block. I can't remember the last time I saw a crank fall out of an engine unless it was a nitro car! Like mentioned above, put your money in rods, get it balanced and you will be fine. Kinda late but what are you building and how much power do you want to make?
Thanks for all the good info, this is going to be a race only engine, how do ya feel about filling this block with grout?
Id be more concerned about quality rods its not too often the mains or crank go south unless under nitrous or forced induction then a four bolt should be chosen along with a steel crank. my.02
2 bolt good to 8,750 RPM. Want to buy it? We ran the **** out of the two bolts. Still As has been stated little more iron in the right places and less core shift that the 4 bolts. Besides nobody wanted a two bolt, 4 bolts were better...ahh have seen no proof of that. We never, ever lost a main bearing in a big block and we tried like hell. Using sticks or automatics. Still do. Prep the bottom for studs and good oiling as well good bearings and you'll break something else before issues with the bottom.
i dont use big blocks that said these guys are on the money .i run 30 nights 38 laps each 8.200 revs non stop .two bolt block with studs.also some times cast cranks work great flex has its good points .ch***is dyno 580 at the wheels .i hope this helps.
I agree growing up all we would hear about is the 4-bolt main 350 etc.My friends 67 nova has a 350 2- bolt and it is a street application and that thing has some torque.Even though it's an automatic she pulls like hell and throws you back in the seat when hit hits it.
I would answer with this. What do the big boys run on raceday? 2 or 4? I think you know! If your gonna race it...the more, the better!
Whenever Chevrolet installed the engines into cars ... the High Horsepower ... solid lifer engines were ALWAYS 4 bolt main blocks. This helped rodders think that the 4 bolts were better. 427 - 425, L-88, LS-6 ... all were 4 bolt ... I believe that a 2 bolt ( properly prepared ) with good ARP bolts will do well ... I have turned the 468 inch BBC engines 7500+ a bunch ... with 2 bolt mains. I believe that good bolts ( or studs ), proper bearing clearances, a good balancing job and careful ***embly ... are neccessary for a long life @ that RPM level.
Thanks again for the info, i think i'm sold on the 2 bolt block ive found after hearing from all of you, just wasn't shure if i needed the 4. Anyone have any ideas on engine grouting?
I ususally use either tall deck 427 blocks or early 454 blocks fitted with the caps off of a 366 junker block to get 4 bolt mains. Never had a problem. I also ran a stock crank but aftermarket rods and pistons. Spun the 427it to 7500+ all the time and the bottom end stayed together just fine. Valve springs hated me however.
Typically speaking it's not the rpm's that kill 2 bolt motors, it's "RPM's" + "Cylinder Pressure". Once you see they've started makin' those tiny snot wads between the caps and the block on a routine inspection,you've seen the handwriting on the wall. Grout works!
A lot of this depends on the engine tune & the tuner. End up with lots of detonation...it won't make a difference whether it's two bolt, four bolt, or cross-bolted mains...you're going to have cap walk...at the very least. Get your tune right & a two bolt 454 BBC block will stand up to a surprising amount of power. Use GOOD lightweight pistons & pay attention to bearing crush/main bore diameters...
I don't think you need to fill (as you say, grout) a block until you want to make over like 750 hp. I'm at about 675, regular, unfilled block. Edit: I don't know where I got the 750 number from. Just made it up. My point is, you can make decent power without a lot of so-called trick stuff.
I was at 650hp on a truck block with a short fill with zero problems. I also added around 350hp worth of hose to that engine though
From what I've heard....the four bolt main bearing retainers were developed for truck engines. It's not the high RPM that lead to problems for two bolt blocks, it was the excessive "lugging" of engines in trucks carrying heavy payloads or trailers. That lugging would evidently start fatigue problems with the two bolt fasteners.
Whats interesting is that the main caps off the truck blocks are much beefier than the p***enger car main caps. Also the cylinder walls seem to sonic check thicker on average. The truck explanation makes sense if you look at these low rpm torquer truck blocks.
This is not going to be a street engine, race only, forced induction alcohol. No i'm not building it, i'm having it built, I was just a little sceared of the 2 bolt. Let the good times roll!
You can get 4 bolt blocks for cheap.........so cheap theirs no reason why not to start out with one. Especially if you know its a race only peice...thats my opinion, Littleman
Yes, i could buy a 4 bolt block, again the man doing my engine work is a respected old drag racer. He personabley believes that the 2 bolt is better when using a early 454 block. He believes if anything the extra 2 bolts makes it weaker, he said if you just think you have to have 4 bolts then the way to go is use splayed caps with angled bolts, but he does not even believe that is neccesary. Now he used to race nitro dragsters " and win " so i'm inclined to listen and learn. This is why i ask for ya's opinions, i'm learning, and believe me, i listen everyone of you and take notes. thanks.
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