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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I'm planning a 383 build and I have 2 blocks
One is a 2 bolt main 4" bore 1pc rear seal roller block
The other block is a 4 bolt main 2pc seal flat tappet block
I'd like to make this build a hyd roller, so if I use the 4 bolt block there will be added expense of retrofit roller lifters
If I use the 2 bolt block it will save me a couple hundred $$
I doubt that I'll be racing much, so it isn't even close to being a max effort stroker.
Is there an advantage to 4 bolt mains that I could get by without - considering that it's an engine that other builders have dyno'd at about 400 hp?
If your true intentions are not to race it, rev it over 6k constantly, or have it produce more then about 400hp then a 2 bolt is just fine. I'd use the newer 2 bolt in that situation. I would reccomend buying new main cap studs though just for added security and if you add performance down the road, you are ready for it.
I killed a 350 2 bolt block but I was reving it to 6700, racing it, and it produced about 500-550hp.. ran 10.70s@125mph. Was a 385sbc. All forged internals didnt matter. My guess is excessive crank deflection on then main caps.
I'm planning a 383 build and I have 2 blocks
One is a 2 bolt main 4" bore 1pc rear seal roller block
The other block is a 4 bolt main 2pc seal flat tappet block
I'd like to make this build a hyd roller, so if I use the 4 bolt block there will be added expense of retrofit roller lifters
If I use the 2 bolt block it will save me a couple hundred $$
I doubt that I'll be racing much, so it isn't even close to being a max effort stroker.
Is there an advantage to 4 bolt mains that I could get by without - considering that it's an engine that other builders have dyno'd at about 400 hp?
Thanks
Use the roller block; have it magnafluxed before any other work is done on it. Additionally, as recommended above, use an ARP stud set for the mains rather than bolts, and you'll be good to go.
I'd use a 2 cap block up to around 550-600hp or so without much anxiety on a street\strip build. Use ARP main studs and shoot for .002 to .0025 bearing clearances. Use a windage tray and crank scraper to reduce oil entrainment. Use an 8" harmonic damper for best results. Obviously you'll not want to live on the rev limited but occasional blips should be fine.
Or you can do what I did with the engine I built for my Express van. Convert to splayed main caps. A splayed 2-bolt block is stronger and more durable than a factory 4 bolt block.
You have to start with the 2 bolt to install billet splayed caps. So that's the one to use. Also the factory machining is probably decent on the 1pc RMS. The other one..... might have some of the 1970's machine work in it. Better to just relegate that to the scrap heap. Vortec blocks are super cheap and available, and aftermarket blocks aren't very expensive either.
You have to start with the 2 bolt to install billet splayed caps. So that's the one to use. Also the factory machining is probably decent on the 1pc RMS. The other one..... might have some of the 1970's machine work in it. Better to just relegate that to the scrap heap. Vortec blocks are super cheap and available, and aftermarket blocks aren't very expensive either.
GD
X10000000000000 I have seen guys wasted alot of money on 2 bolt blocks when using a 3.750 stroke crank. Look even when GM used a 2 bolt 400 block they used the same wide register, 2 bolt blocks don't like stroke or RPM. I installed a lot of splayed caps on 2 and 4 bolt caps once they pass a sonic test. Machine work on the later blocks as mentioned seems to be much better as far a s locations go.
Any time main caps are replaced, the block needs to be line honed so factor in that expense as well.
As nice as it is to "build an engine", calculate the cost of all the parts and get an estimate from a machine shop for all the machine work that should be required. In the end, it can be a lot cheaper to buy a replacement crate engine with all that work already done for less cost.
You can get a complete 383 engine, less intake from Blueprint engines for $4399. That's with a roller cam and aluminum heads. Rated at 430 HP
The advantage of studs is how the clamping force is applied. Mains or head bolts need to twist the bolt to apply clamping force. This can distort the area around the threads which can cause weakness. With a stud, the stud itself is simply snug in the threads. Tightening the nut doesn't turn the stud so all the clamping force is applied by the nut turning on the stud.
I've broken a few engines at the track. Common causes for me are failed rod bolts or failed rods. I've only damaged a crank or a block after something else has failed. Crank and rods are now billet so the chance of them failing now is slim. I found I-beam rods lighter and stronger than H-beam rods.
Aside from the advantages AlkyIROC mentioned, studs also tend to provide more consistent clamping forces since there's less friction and\or foreign objects (read: garbage in the threads) providing resistance. This, in theory, should help prevent cap walk as the studs\nuts should be clamping evenly and none of them under-torqued.
Aside from the advantages AlkyIROC mentioned, studs also tend to provide more consistent clamping forces since there's less friction and\or foreign objects (read: garbage in the threads) providing resistance. This, in theory, should help prevent cap walk as the studs\nuts should be clamping evenly and none of them under-torqued.
Check this thread out and go to the 3rd reply this guy got a lesson as some idiot told him a 2 bolt was good for 500 horse LMAO
Keep in mind it was a circle track car... They typically run a lot higher RPM than a typical street\strip car and at the bleeding edge of compression to stay within their rule limitations. I'd be willing to bet they were likely having detonation issues. I'd have no qualms running at that level with a 2 bolt main cap without boost. Cap walk that bad with 420hp naturally aspirated? Please. Either it was tuned poorly or the machine work\assembly wasn't performed correctly (or at all).
A quote from "How to Build Max-Performance Chevy Small Blocks on a Budget" by David Vizard.
Unless you're trying to convince everyone here that David Vizard doesn't know what he's talking about... I personally will put my faith in Vizard. I'm betting he's spent more time building and testing engines than most of us put together.
Keep in mind it was a circle track car... They typically run a lot higher RPM than a typical street\strip car and at the bleeding edge of compression to stay within their rule limitations. I'd be willing to bet they were likely having detonation issues. I'd have no qualms running at that level with a 2 bolt main cap without boost. Cap walk that bad with 420hp naturally aspirated? Please. Either it was tuned poorly or the machine work\assembly wasn't performed correctly (or at all).
A quote from "How to Build Max-Performance Chevy Small Blocks on a Budget" by David Vizard.
Unless you're trying to convince everyone here that David Vizard doesn't know what he's talking about... I personally will put my faith in Vizard. I'm betting he's spent more time building and testing engines than most of us put together.
He also say put a crank in the block if it spins its fine WRONG One of my customers tried that with an old truck block where the caps were out of shape were and .002 over size from 12:00 to 6:00 Nice e call Vizard.
A Vizard has more knowledge then GM ya right GM has done more testing on what works using a 2 bolt VS a 4 bolt the Vizards, Get a life
Go ahead put over 500 horse to a 2 bolt let me know how it works out it a waste of time. Some of his advise does not apply to what I do as I don't take chances with peoples money. If your a buildig budget deal and want to take the risk go ahead.
500 hose maybe with a 3.250 stroke 3.750 stroke its not going to work
Didn't see GM making much power at all in any production stuff with the sbc, regardless of it being 2 bolt or 4 bolt.
Can you source where Vizard says to just spin it and says its fine? Seems contrary to just about everything I've ever read. As a matter of fact he usually provides lots of data about what he finds is acceptable and what isn't. Page 35 of "How to Build Max-Performance Chevy Small Blocks on a Budget"
I think a few bad experiences have jaded you to the thousands of successes. The world isn't black and white. There's too many variables to say what will and won't work.Too many different levels of expertise. A 600hp SBC might live for a hundred thousand miles if it's never beat on, or a 300hp SBC might live two nights at the dirt track because it's flogged within an inch of it's life from start to finish. Or a 300K mile 5.3 with a pair of ebay turbos might put us all to shame for $800.
500 HP isn't at issue here. Doesn't make sense to argue about what it takes to get that with reliability intact.
The OP says "other builders have dyno'ed at around 400 HP". Given the usual results from a typical amateur copying a professional build (no offense meant), I doubt 400 HP is even in the cards here. But even if it is, that still only requires making peak torque at around 3800 - 4000 RPM which will be in the 460 or so range, and peak HP at around 5200 when torque will be down to around 400. All these #s are assuming pump gas of course. Not exactly a high-stress application for a block.
The OP would do better to use the later block, dodge the 70s crappy factory machine work and other built-in unrepairable (at an economically sensible level) flaws, and just build yerbasic 10:1 350 with some half-decent aftermarket heads and a 230ish duration hyd roller cam well-matched to the heads' flow properties. Splayed 4-bolt mains aren't needed for that. Factory 4-bolt mains are useless in such a situation (or just about any other besides a truck for that matter). In every way, the stated goal fails to benefit from, let alone require, any kind of 4-bolt anything, especially not if it requires money or effort to make it happen.
Didn't see GM making much power at all in any production stuff with the sbc, regardless of it being 2 bolt or 4 bolt.
Can you source where Vizard says to just spin it and says its fine? Seems contrary to just about everything I've ever read. As a matter of fact he usually provides lots of data about what he finds is acceptable and what isn't. Page 35 of "How to Build Max-Performance Chevy Small Blocks on a Budget"
I think a few bad experiences have jaded you to the thousands of successes. The world isn't black and white. There's too many variables to say what will and won't work.Too many different levels of expertise. A 600hp SBC might live for a hundred thousand miles if it's never beat on, or a 300hp SBC might live two nights at the dirt track because it's flogged within an inch of it's life from start to finish. Or a 300K mile 5.3 with a pair of ebay turbos might put us all to shame for $800.
I have also seen plenty of stock 4.8s and 5.3s that were well maintained yet still failed catastrophically with half that many miles. Metal fatigues and things break.
I have also seen plenty of stock 4.8s and 5.3s that were well maintained yet still failed catastrophically with half that many miles. Metal fatigues and things break.
Well, I guess I can't feel too bad about never finding good deals on a 6.0 that isn't somehow fornicated, then.
I find 2 or 3 trucks a week with 6L that have bad engines. My last 2 6L were $400 each. One was running with 80K miles. The 2nd was a block and crank fresh from the machine shop and a couple of box's of parts. You guessed it a LQ9 with oil pressure loss from bad cam bearings. However it did not spin them.
No such luck up here. A long block with accessories goes for about $1000 with 150-200K miles on it. We pay about $400 for a complete 200K 5.3 or 4.8 around here.
No such luck up here. A long block with accessories goes for about $1000 with 150-200K miles on it. We pay about $400 for a complete 200K 5.3 or 4.8 around here.
The last 5.3 I bought intake to pan water pump to flexplate cost me $150 at Pick and Pull. Someone was already thoughtful enough to have removed the whole front clip and the transmission. Couldn't pass it up. I also picked up one with a slightly burned intake one for $100 a while back.
This must be why my buddy keeps trying to convince me to move down there. He lives down in Beeville from around September\October to April or May. He just avoids the Minnesota winters. lol
Thanks for all the replies guys.
There's a lot of info there that I wasn't aware of prior to this.
I have a 2 bolt block that came from a TBI truck that never turned over 5k because it couldn't
I remember finding this out when I tried flooring it in park and either there was a rev limiter built into the computer, or the ign module just was incapable of producing spark at that RPM.
Anyhow - The truck was a dog and went through a lifetime of usage that was fairly free of stress.
That's kind of a good thing to know considering the fatigue of parts before it's first rebore is minimal.
So that's a plus
I have to confess that this is for an engine that will be used in my pickup.
Guys here are more knowlegeable than the guys on the Chevy truck site.
It will be a 9:1 CR 383 with a cam of about 218 deg @.050"
Last edited by ironhead88; 07-23-2019 at 06:46 PM.
07-07-2019, 11:34 PM
