SBC Chevy Build - Do you need a 4 bolt main block?? Will a 2 bolt block work?? 
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- Опубликовано: 18 сен 2024
- In this video I describe building a 406 Small block with a 2 Bolt main. Why didn’t I use a 4 bolt main?
Watch and find out!
#horsepower #chevrolet #chevy #sbc #racing 
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I grew up watching my dad race a 55 Chevy Gasser with a 327 with a M22 Muncie 4spd. He made 500hp and never had an issue with a 2 bolt block. He turned 7,500rpm all the time. He had some special things he did with the oiling system on the cranks and cams. He opened the oil passages and ran a high volume oil pump. Back in the day having a high volume oil pump was a big deal. But back in the 1970’s dad had very few engine failures. The key to shifting at 7,500rpm was keeping the engine well oiled. Dad’s little 327’s would gap the Big Block Mopar’s back then. They could not believe the little 327 would turn those RPM’s and say together. Dad never had the hood up at the track. He always said races was won in the shop. We pulled the 55 Chevy two door post Gasser on a two rail trailer. Our tow vehicle was a 55 Nomad with a built 327, 4spd. We always had parts. I remember going to the Nationals in Indy one year. And this was a rare time he had engine problems. We pulled the 327 out of the Nomad and put the two 4 barrels on the tow rigs engine. We finished the race week with the 327 out of the Nomad. People could not understand how we was winning races with the tow rig engine. These 2 327’s was built exactly the same except the gasser ran two 4 barrels. Dad already had a high volume pump in the tow rig. He only needed to change the single 4 barrel on the Nomad to the Twin 4 barrels. I was only like 10yrs old, but I remember the tow rig engine was 2-3 tenths faster than the Gassers race motor. He had been playing with match porting on the heads and intake, but it was untested. So he just used it for a backup in the tow rig. After that week of racing and everyone was leaving, we was in the pits putting the race engine in the tow rig to drive home. Thats when drag racing was super fun. 🇺🇸🦅🏁🔧💸
Wow, what an awesome experience and memory, thanks for sharing. AG
We always used 500hp as the deciding point.. Below 500 a 2bolt was fine, above 500 we went 4bolt. If I couldn’t find a factory fourbolt I went splayed on the center 3 caps with a two bolt block. Splayed two bolt to me is better than factory 4 only because the outside bolts are angled.
At 8k I have seen the crank rods and pistons take the pan out n put everything on the track.. at 6 k and 500 Hp a stock two bolt will live forever.👍🏻
Tighter quench decreases detonation and increases mixture motion. Both good things..We run em tight enough they just leave a shine on the heads... Keeps the rods from stretching lol 😂 Great Video Allen!
And how tight would that be??
Thanks Phil. AG
@@jeremymyers5643 Down to .020 on sbc race engines and .033 on bbc.. These are with steel rods and turned in excess of 8k rpm. You’ll see just a faint print or clean area on the head where they’re not hitting but close enough that the surface doesn’t turn black.. Not recommended unless you’re really trying to squeeze every last bit out in a max effort application but proceed with caution..
Hey AG,
Tim here, my Pontiac has 2 bolt mains.....i've made a documented 590 hp/625 lb ft with it......yes its a drag application, but 2 bolt mains WONT be a deciding factor if catastrophic engine failure happens, it wud be in tune/valvetrain......if ur using a GOOD rod, i DONT see any issue, i walked over my stock rods yrs ago on my Poncho.....LOTS of damage, NOW i got Eagle H-beams, my man Jeff at Kauffman racing assured me i'm fine.....all i'm saying is a proper rod for the abuse shud be employed.....i think ur just fine.....and i wish you and ur son GREAT luck, wud LOVE to hear about a great season!!!.... GREAT vid, i enjoyed!!!.....PEACE to you sir!!
Yeah, always upgrade the rods on a Pontiac if you're increasing power, those factory cast iron rods are junk for a performance engine, unless they're forged Super Duty rods.
Also although Pontiacs have 2 bolt mains, the caps are doweled as well. Cap failure happens when the caps move around that's why extra bolt mains are helpful. But if you have dowel pins keeping the cap from moving even better because there is more meat in the main webbing.
And Chevy 4 bolt mains are great for a plow truck or heavy towing when there is a very heavy load. But for higher RPM lighter loads, 4 bolt mains aren't as important. But for a heavy mudder truck with huge heavy tires splayed caps are the only way to go with a sbc 400 block or the crank can get spit out in the mud with a factory 2 or 4 bolt main block. The weak main webbing busts right off. Splayed caps the angled bolt goes into the strongest part of the block. Halo girdles also help spread the load pulses.😎👍
@@itseithergonnaworkoritaint7852 thanks brother, yes i got dowels for the caps, now i spin it to 6200 w/o worry (but thats max, my 4.210 crank donk like high rpm)....bit she's holding now........gotta say, i POUNDED on my stock rods for 7 years, it saw 6000 rpm often.....then 1 more time, let everything go.....was bad......only salvage was intake, carb, and headers.....all rest was destroyed.......it was fun!!!...HAHA......yea, ur mud pullin trucks see dif loads than a drag car.......i DEEPLY appreciate ur comment....TY sir!!!....PEACE!!
@@TimothyArnott-m7z
You're welcome, sounds like you had some fun. Yeah those 455 rotating assemblies aren't light and the piston speed is zooming with that stroke plus the main bearing speed from those huge mains don't like to RPM. But with all those cubes you really don't need to especially if you have good gearing.
Yeah, cast rods anything over 5,800 they can't handle the harmonics, they start forming pre crack cracks that eventually turn into cracks. Cast rods are ok for an engine that never sees over 5,800 RPM, they'll last forever. Over that they start degrading from the harmonics.
A catch 22 for that is running turbo boost because of how both the intake and exhaust is under a load going down and up to push the exhaust through the turbo that helps cancel out the harmful harmonics. This is where you can find the limits of the bolts and or test the strength of the cast iron.😎👍
@@itseithergonnaworkoritaint7852 hahahaha, yes, luckily i will stay NA......maybe down the road a 150 shot, but i like NA in general......and YEA, wish i didnt have such LARGE mains......i know they thought it wud be good, but, WAY to much heat generated at that speed....a stroker crank with 3" mains is a MUCH better choice......but my '70 455 block is holdin up.....7'0s 1/8th, 11'0s qtr at 99/120......i WANT that 10:99....with a 9, but it escapes me......i'm right there, all pump gas (10.44:1 static, alum heads, NOT Edelbrock, Kauffman Racing)......THANKS for the chat my brother, i appreciate ALL of it!!!.......ICE for life!!
I'll never understand why Pontiac decided to cast their connecting rods when most every other OEM were forging their rods.
The 2 bolt 400 is stronger because of the increased bolt spacing versus 350/400 4 bolt main, bolt spacing is increased w/ 2 bolt 400 to accommodate larger stock 2.65 journals.
Thanks FZR, the larger journals is an important point that i forgot to mention in the video. AG
I got my old square body stuck in a river and sent the connecting rod through the oil pan. I got pulled out but I had to cross the river because I was on the wrong side. I drove the truck across the river because it still ran. My help abandoned me, so I drove that truck home 10 kilometers with a horrible knock and no oil. I'm impressed with the small block Chevy.
Great experience, thanks for sharing. AG
Great video! I can’t wait to assemble it with you.
Me too, thanks Son. AG
With the 400 block, I think the 2 bolts are stronger than the 4.
Thanks David, that is a common belief also. AG
Another fine video AG! Look forward to your next one..👍👍👍
Thanks Steve. AG
I gotta admit, you are one of my favorite engine building channels on RUclips! I like your no nonsense presentation.
Thanks for the nice compliment Robert. AG
Brings back memories Mr G. Late 70's tech college built 400 with fuelie heads. BUT, 6000 RPM for an extended run with the stock valvetrain resulted in a misfire. Engine death came weeks later when the misfire said the bent valve that caused the misfire ( which was missed in the troubleshooting) decided to leave the engine. Catastrophic failure indeed! Keep up the good work.
Thanks Kevin. AG
Excellent video! I especially liked your explanation of the forces the connecting rods endure. I genuinely wish that I could sit in on the class you're teaching later this month. I am also very interested in seeing Michael's engine come together and the follow up on his success this racing season. All good stuff, Allan. Thanks again for another interesting and informative video. I'm learning a lot! Cheers!
Thanks for the comment Todd. AG
Thanks for another informative video! I would like to see , if possible, a video on quench = piston height, cylinder head volume ( cc's) and head gasket thickness, etc. Thank you for what you are doing!!!!
Thanks Mr., we will get to that in time. AG
Here's an idea for you, build a 377(400 block with a 350 crank)so you can run a 6.125" rod with pistons that have a 1.150" compression distance. The longer rod shorter stroke will be less detonation prone because of the extra dwell ATDC. And engines with a shorter stroke make more power per cubic inch. Look up the HRM article from June 1997, "The 350 Engine Chevrolet Should Have Built" is a great example of that.
With anything longer than a sbc 400 rod with a high lift cam you're going to need a reduced base circle cam with the 3.75" stroke. Not the case when running a 350 crank. Plus you would be able to rev to 6,500 all day long and up to 7,000 on occasional short bursts.(As long as you run at least studs in the 2 bolt block, a halo girdle would help too)
With the right heads, cam and compression ratio your HP goal should be no problem. Although it will be slightly down on max torque compared to a 406 but not enough to notice in a light race car. Probably would be better with a little less torque and a bit more high RPM HP?🤔😎👍
Great information, thanks for taking the time to contribute to my channel. AG
Thanks for sharing your experience, Alan- would you mind sharing more details on the build- head specs, cam specs? This sounds almost exactly like the specs of my 400 that I’m building.
I look forward to your videos, so keep them coming.👍🏻
Sure Leo, we will make more videos about this engine with all the details. AG
That engine is going to run great!!!
Thanks Grand. AG
Thanks for sharing your wisdom with us!
Hey Mr. Gold I'm building a 2 bolt chevy 454 with very wide caps the engine will be show will run a blower can you take about that sometime thank you love the videos keep them coming
Thanks for the nice comment RK. I have never built a blower motor but my friend Bill Little has build many. We will try to feature him in a future video. AG
@@goldsgarage8236 thank you so much that will be cool 😎
The reactions I get when I tell people that a friend has a 55 Chevy that runs 10.teens with a 355 2 bolt engine are always amusing, with most saying that engine will never last.
Then I tell them that engine has many hundreds of passes on it, with no main cap movement. And as it is burning Methanol, it never detonates!
Thanks alleyoop. Great info. AG
I'm no fastener expert, but I've read from various sources that an up grade to a two main would be studs. So that's what I do on both my big and small blocks for what it's worth.
Thanks Joe, AG
Love the budget build series of videos… but it seems on quite a few videos (from various presenters) there is a point in the build where it goes “sideways” and the builder uses some “unobtainium” head or valve train, rather than off-the-shelf items. “I had these expensive heads in the back and this high end valve and rocker setup leftover that I’m putting in at a discounted price”. I have a ‘76 Vette that has 110k miles on the engine and want to do a performance rebuild, but certainly don’t have heads and other performance parts sitting on the shelf. (Nor does my local engine builder - and I don’t want Marketplace crap to gamble on).
Perhaps discussing what heads, that are affordable, (AFR 195’s etc) with reasonable rockers would be useful alternatives. (Obviously affordable is a relative term).
Otherwise, interesting videos which address the theory.
Good suggestion Mark, I have a new set of heads "affordable" still in the box that i will discuss on a future build. AG
Thanks for your thoughts on sbc , for what it is worth I think you need to up your compression ratio. With the cam or static I would go static first,depending on weather you want to be in the middle of the pack and reliable or closer to the front of the pack and little less reliable , that is if the class lets you run race gas.as I am sure you know that lower compression ratio will cost you torque. Thanks Dwayne newzealand.
Thanks for sharing your knowledge and experience Christopher. AG
I love this channel
Thanks Mongoose, more to come. AG
Michigan modifieds run more than 500hp here in Michigan. There upwards of 600-700hp now, and upwards of 8500 rpm. You better be upping your game.
Thanks for the info Jay, you have me worried now! AG
I don't have to watch thr video to tell you "YES". I've built my fair share of 600+ 2 bolt main SBC. I use SCAT 9000 cast cranks and the longest rod I can depending on piston and the budget.
Thanks for the info Arturo. AG
Thannk you for the video
Always look forward to yourvideos
Thank you Nerrad. AG
hey Alan, Jerry here down in Ky. People talk and ask, does it have a 4 bolt main block? I say why are you so worried about it? You are not making that much horse power. In the 70's we were turning 327's and 302 Z 28's to 8,000 RPM's all day long and not having any problems on a 2 bolt block. In 1976 we had a A/AA dragster with a 392 Hemi with a 3/8 stroker crank and turning it 8,000 RPM's on a factory 2 bolt main block and was National Record Holder at Beech Bend Park,,,,, For a little peace of mind on my 406 sbc 500 + HP, I like to use ARP main studs
and by the way if you are not familiar with a 392 Hemi, they are a 4 inch bore and a 3.900 stroke, so they are not a factory high RPM engine to begin with and in the spring of 76 or 77 we were at a points race at Indianapolis Race Way Park, and the local newspaper wrote an article saying that we qualified 8th in the Top Fuel class running on alcohol. Jegs Caughlin owner of Jegs Warehouse was pacing back and forth in our pit and Joe said, "Jegs can I help you?" and Jeg's said " How do you get this junk yard junk to run so fast?, I've never been passed in the middle of the track by one of these long stroking motors !!",,, Of course Jegs was running a 426 Hemi, bigger bore and shorter stroke
That is a great story Jerry, and a great accomplishment. I responded to your text last night. AG Thanks for sharing. AG
Heavy H-beam rods built for high compressive force are becoming popular because of high boost turbo applications.
I swear I heard this was a race motor. 0.042" to 0.045" quench isn't bad, but my mother's daily driver has less.
How about putting a call in to Cometic for a 0.030" head gasket?
I'm building a 2 bolt 010 with splayed caps (not cheap to machine).
It's an expensive process for sure, thanks for the comment. AG
Great video. Im building a 406 for my Chevelle. My goals are the same as yours power and rpm wise. Can you share the cam specs?
I was thinking about using a speedway oval track cam. It's 229 @ 50 and 106lsa.
Sure, I will share all the details in future videos about this engine. AG
good stuff. do you ever build any old FE engines?
Thanks Lone, not sure what FE means? AG
I heard you talk about powered metal having good tensil strength.metal is partly your profession,yes?
Thanks David, yes, my corporate career was in steelmaking. i have a diploma in Mechanical Engineering. AG
If you dont beleive in when you lift an engine will break, then try open headers on stock engine and lift right off at end of 1/4 mile once .
good point! AG
A 2 bolt block is fine for what your doing with it .
Thanks for the affirmation Andrew. AG
Frost plug
Freeze plug
Core plug
Welch plugs
All the same thing mate
Correct. AG
Bung....😅
Great video, it's very hard to find a 400 sbc that is std. bore, How much can the block be bored out safely? I find a lot that have been bored +.030 and are rusty, can the shop do+.010 more?
Thanks Jan, usually they can but it should be sonic tested beyond .030" AG
Alan, did the shop sonic check the cylinder wall thickness before boring 0.030”
I don't think they normally to a sonic test unless it is more than .030" We did sonic test for Roberts 302 for .060" however, AG
2 bolt is fine use it.
Thanks Bo!. AG
Dowl pin the caps.
Thanks Racer. AG
Did I see just 2 bolt mains on the DZ 302 block ?
It’s not a DZ, it’ a 68 MO block.
Found a few 400 blocks on marketplace but don't know what you're getting and people lie 😢
I would never touch a gm 400 block again that I personally didn't own and have when running that would almost guarantee it to be problem free. For high performance anyway.
@@jeremymyers5643 yeah it's risky as hell unless it's $50
I'm just curious. Is my cast factory GM crank ok for 500 hp. 2 bolt 400. 69 Camaro street car. No racing????
The crank yes, the rods only if the bolts are upgraded and the beams are polished and then shot peened and match balanced. Unless you can do that yourself you're better off upgrading your rods because it'll cost less.😎👍
Scat 6 inch full floating rods.
@@ericuncapher9922
Those should be good.😎👍
Oh, if you're going to have a cam with more than .500" lift you should get a small base circle cam so there isn't any cam to rod clearance issues.
I just ordered a Howards roller cam 525 lift 225 dur at .050. I hope it fits. The guy from Howards said it would. But he didn't know or have small base circle part number. Yhaaaaaa!!!!
@@ericuncapher9922
If the short block is assembled waiting for a cam you can look through the cam tunnel and rotate the crank then watch for the shoulder of the rod to travel above the cam bearings. If it does you will probably need the small base circle cam. If it doesn't you probably won't. If those are the Scat stroker rods you'll probably be ok because that's not that much higher than.500" lift?
My 383 basically has a .516" lift regular base circle roller cam but it only has 202°/212° @ .050" without any issues. Also I have 5.7" rods too which is in my favor as well. Longer rods don't angle away as much as a shorter rod will is something to consider on this comparison too.
The sbc 383 I built for a friend needed a small base circle cam because it is a Howards solid roller .585"/.585" lift and it didn't clear. He has 6.00" H-beam rods, those don't have much clearance though.😎👍
It's1969 Z 28 not Zards 28 😢
Zed 28 where I live, not where you live! Who is correct??
I think he says "Zed 28" the way Canadians refer to the letter "Z".😂
@@alleyoop1234
If you call the letter "Z" Zed when it's used in other words it clearly sounds like "Zee" which one do you think is right?😁
1969 Z28 or Zed 28 I just wish I had one that is my favorite car love the u tube channel lots of good information
@@itseithergonnaworkoritaint7852 Zed is correct. That's why the entire english speaking world, except the US, says Zed, not Zee..
How do I contact you
226-980-7499
This video was really gutless and lots of rambling. Didnt really give us solid information that matches the title of the video
Then don’t watch, but stop with your unnecessary, complaining comments. He’s sharing his opinion and experience.
Thanks Leo. AG