The 4 bolt main LIE !!! Or is it???

[Jrgunn5150]

It's the internet, everyone is swinging for the fences lol, buy once cry once, done right the first time.

I just like my junk to go down the road.

I'll take my unknown miles, not rebuilt, 170 dollar junkyard engines over anything that's been analyzed and inspected to death. I can always just go get another. Irony is, the less I care, the less they blow up. Learned that lesson back in 08 or so when my Dart block got ruined and I have 9 stock 5.0's sitting around to go run that weekend.

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[HotRodPC]

All Gen 5 and Gen 6 BBC blocks are factory 4 bolt, with parallel drilled bolts. The only way to build a splayed cap BBC is to use a MK4 2 bolt, or buy an aftermarket block.

You're absolutely correct on the oil galley. My machinist drilled right into them. His approach to this was to chuck up 3 studs in a lathe and cut them down so they would bottom in the galley, but let oil flow around them. I didn't care much for that idea, so I made plugs that bottomed in the galley, then drilled through them from the side. It's hard to explain.

Next time I'll just buy a Dart Big M block. The machine shop costs, and material cost for me to do this was only about $1K less than a new Big M.

As for the 2 bolt vs 4 bolt argument, I'm in the splayed cap fanclub.

I guess the oil restriction might be hard to explain, but I 100% get it. Many don't call it that, but it is OIL RESTRICTION, you're restricting the oil to the top end since it's getting plenty as it is, so no sense in sending to much oil up there leaving the bottom scavenging for oil since it flows up by pressure but only comes back down by gravity and that takes much longer since it's not under pressure. So by restricting the oil going up to the top end, ensuring you're keeping enough in the pan. But yes, I get your technique too. That's usually necessary on anything you're going to be running high rpm for any length of time at all. I for sure restricted my small blocks EVERYTIME cuz they were spinning 6500-7000rpm. Me too, my vote would be for splayed mains if I felt the need. It's not cheap though. First buy the caps, then drill and tap the block, and finally, Line bore the block and new mains.

 

[Craig Nedrow]

I have only blown one engine, 216 Babbitt bearing in a 1949 Chevy. Every engine I have built was balanced, I believe this is key. I ALWAYS drive hard, personally seen 10000 rpm on 283s and 327, never blew up, two bolt. My 350 circle track motor still is with me after being in three different rigs, all pedal to the metal. The 489bbc is studded two bolt, but balanced to .02 grams, not the normal 2 gr. I have seen factory charts that showed how much in balance force was by RPM, a real eye opener. My block is a Mark 4 out of a motorhome. If interested, here is the build. I am a machinist by trade and have worked in an engine shop, this is my rendition based on 40+ years of messin with engines, studying, and hands on.

https://www.gmsquarebody.com/threads/bbc-489-build.45389/

 

[Sgt Gus]

I started to build a 2-bolt 454 cid big block ..
Got pretty far into the build before I decided to do a 4-bolt ..

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This motor was mostly stock, rods, crank and pistons were Oem, never been apart since leaving the factory ..
Came from a motorhome with low mileage on the clock .. Was intending to low ball the build and roll the dice ..

Then I got to thinking about horse-power ..
I'm sure the 2-bolt could handle 400 or 500 ponies and stay together doing so ..
But not so sure about 600+ and taching to 7,000 rpm's ..

Okay ... For peace of mind I choose to go with a seasoned 4-bolt block with hi-po parts .. Goodbye Oem ..

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Forged steel 4340 stroker crank, H-beam rods and forged .080" over pistons took the 454 BBC to 500 cubies ..

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A 4-bolt main block is better for high-performance applications that involve extreme horsepower, high RPMs, or forced induction (like nitrous or a blower). For a standard street engine, however, a 2-bolt main block is often more than sufficient.
In the future the motor just might see a blower ??

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Got room for it and still be able to close the hood ..

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Keeping it a sleeper ..

Do you run into heat issues with the domed pistons at the heads? I believe the heads on out bb run an easy 25° more than the coolant. Gauge Temp sensor in the head of course.

 

[Craig Nedrow]

Sadly I have not run the motor yet, sick wife, hernia, etc. Hope to have it in the truck and running but not driving in a couple months. Doing body work now....

 

[idahovette]

Hope your wife is on the mend................does she have the van done yet?....is she slackin' on the job?..... Seriously, hope she is getting better

 

[Shorty81]

Hope your wife is on the mend................does she have the van done yet?....is she slackin' on the job?..... Seriously, hope she is getting better

^^^^^^^^^what Perry said^^^^^^^^^^^ !!!

 

[Craig Nedrow]

Ornery as ever and feeling good, bout of us are. We are gonna stay where we are at. So we mostly finished the new garden area. Next week rack on van, maybe A/C, paint rack, and etc. one week. Then back on the Nova, and K20.

 

[Sgt Gus]

Sadly I have not run the motor yet, sick wife, hernia, etc. Hope to have it in the truck and running but not driving in a couple months. Doing body work now....

Prayers for healing Brother.

 

[Craig Nedrow]

Hey Sgt Gus thanks brother. We are doing good this year, and plan on staying that way. Jan is onery as ever, and we are working on her van rack this week hope to get the rack assembled, solar panels placed so then I can cut, (shiver) a hole in the roof for the A/C/ heater. WIll show pic as we progress on her Van build page.

 

[idahovette]

So @Craig Nedrow not moving, huh? Decided to stay home and deal with everything? My Bride and I moved about 10 years ago and it just about killed me. That's when most of my back trouble began. NOT gonna move again EVER!!!!!!

 

[CountKrunk]

Last time we moved we hired movers to load up and unload the truck. Best decision for sure.

 

[HotRodPC]

I have only blown one engine, 216 Babbitt bearing in a 1949 Chevy. Every engine I have built was balanced, I believe this is key. I ALWAYS drive hard, personally seen 10000 rpm on 283s and 327, never blew up, two bolt. My 350 circle track motor still is with me after being in three different rigs, all pedal to the metal. The 489bbc is studded two bolt, but balanced to .02 grams, not the normal 2 gr. I have seen factory charts that showed how much in balance force was by RPM, a real eye opener. My block is a Mark 4 out of a motorhome. If interested, here is the build. I am a machinist by trade and have worked in an engine shop, this is my rendition based on 40+ years of messin with engines, studying, and hands on.

https://www.gmsquarebody.com/threads/bbc-489-build.45389/

100%, Balancing is Key for sure, without a doubt. This 10,000 rpm, for sure on a 283 due to the short stroke I see it happening, and if the 327 too, I'm going with it was a small journal engine and not a large journal. Those small journal engines loved loved loved spinning up the rpm high and tight. ALL SMALL JOURNAL engines were also factory forged cranks. No Cast cranks in small journal engines. Those smaller journals made it easier to spin the RPM and the forged crank and balancing helped it stay together, even on 2 bolt mains. I spun a small journal 327 to 8000 with the cam I had in it. It made peak power to 7200 rpm so that's where I shifted, but I could easily rap it to 8000 just to max out my tach. That's screamin !!! I'd put that truck in 1st and just hold it there at 6000 for like half a block and my buddies are pulling their legs up in the seat thinking the engine is coming through the floorboard. LOL, then I'd bump that ratchet shifter to 2nd and slam the back of their head on the back of the cab. Ohh man, I'm telling you, I beat up on people just taking them for a ride. My daughter 3 at the time, called it the hoppin truck. Cuz I could hold it in 1st, stab it and release, stab it and release, stab it and release, and no seat belts in a 64, but she's sitting next to me while I do this and she's bouncing like a basket ball on the seat and did hit the ceiling in the cab a couple of times. She loved it. So she'd beg for going for a ride in the hoppin' truck and make me do that thing daddy. LOL It was a fun truck. My daugher was born on a Friday morning. She went home Saturday morning from the hospital and was at the Street races with me Saturday night getting introduced to all the friends and race buddies. I did have ear muffs for her, and no I dind't race with he in the truck, but I did race that night. My grandma wanted to kiil me. You can't take that baby to the street races. LOL Wanna bet?!?!? But yeah, Grandma got to keep her about every other Friday night, and I'd pick her up Sunday morning about 6 or 7am on my way home from Saturday night street racing cuz they was over about daylight. But she did go to the street races with me many times and loved it.

 

[Ricko1966]

^^Your small journal cranks are going to have much less bearing speed. Look how much less distance a small journal bearing has to travel vs . A large journal multiply that times however many thousands of times per minute.its huge and the more rpm the bigger the spread.

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[HotRodPC]

^^Your small journal cranks are going to have much less bearing speed. Look how much less distance a small journal bearing has to travel vs . A large journal multiply that times however many thousands of times per minute.its huge and the more rpm the bigger the spread.

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Not sure I understand what your getting at with the math here.