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-   -   Better core block for sbc 383, 4-bolt flat or 2-bolt roller? (http://www.hotrodders.com/forum/better-core-block-sbc-383-4-bolt-flat-2-bolt-132918.html)

Cousin_Joe 02-05-2008 06:53 PM

Better core block for sbc 383, 4-bolt flat or 2-bolt roller?
 
I was planning on building a 383 out of a 1973 4-bolt main block that I picked up in pretty good shape. I went to buy a set of 98 vortec heads, and the guy threw in the block for free, so I said I'd take it! It's a 2-bolt main, but being from 98 it is a roller. He said that he pulled the motor when he heard the bottom end making some noise. I haven't gone thru everything yet, but I did find a nice 1-inch metal shaving in the oil pan to support his claim. I obviously have not had the new 98 block inspected yet, but all things the same, the question is... Which block would you use to build a torquey 383 for the streets? Thanks! :P

Red neck blazer 02-05-2008 07:01 PM

Better core block for sbc383,4-bolt flat or 2-bolt roller
 
I would go with the 4-bolt.You can alway spend a little extra and pack it with roller parts. But thats just me.

Arcuden 02-05-2008 11:12 PM

I would probably go with the late-model two-bolt. I prefer a roller valvetrain and I don't like retrofitting since it is really expensive. Additionally, that late-model block is a one-piece rear main seal which will be better than the old two-piece design.

You only need be concerned about using that 4-bolt block if you're going over 500 horesepower or running at sustained RPM, neither of which sound likely in your case.

CNC BLOCKS NE 02-05-2008 11:26 PM

Quote:

Originally Posted by Arcuden
I would probably go with the late-model two-bolt. I prefer a roller valvetrain and I don't like retrofitting since it is really expensive. Additionally, that late-model block is a one-piece rear main seal which will be better than the old two-piece design.

You only need be concerned about using that 4-bolt block if you're going over 500 horesepower or running at sustained RPM, neither of which sound likely in your case.

A 2 bolt with 3.750 stroke will cause the caps to walk as we have seen this to many times thats why the 400 2 bolts had wider caps that make them more stable with the longer stroke which adds more side load to the caps.

A 383 with Vortec heads should make 500 foot pounds of touque.

Here is a link to look over http://ls1tech.com/forums/showthread.php?t=652566

And on those 1 peice seal blocks you can use a 2 peice rear seal crank with the right adaptor.

Bat 21 02-06-2008 02:34 AM

Just have them install 4 bolt splayed main caps when you take it in to get machined. The caps with arp bolts are only a couple of hundred at Summit. I'm using 2-2 bolt blocks now over 500HP, had the splayed 4 bolts installed.

curtis73 02-06-2008 04:25 AM

Swapping a roller cam into an old block costs a lot. Machining a 2-bolt block for 4-bolt caps is cheap. Not to mention a 2-bolt block will take a good bit of abuse. I'm running a 2-bolt right around 430 hp and I don't worry a bit about it. 116k miles with no issues.

Roller cams are super nice, but retrofitting one is expensive and not worth it. Go with the roller block. If you need 4-bolt mains, have it machined.

CNC BLOCKS NE 02-06-2008 07:10 AM

Quote:

Originally Posted by curtis73
Swapping a roller cam into an old block costs a lot. Machining a 2-bolt block for 4-bolt caps is cheap. Not to mention a 2-bolt block will take a good bit of abuse. I'm running a 2-bolt right around 430 hp and I don't worry a bit about it. 116k miles with no issues.

Roller cams are super nice, but retrofitting one is expensive and not worth it. Go with the roller block. If you need 4-bolt mains, have it machined.

Tell the guy in the link I posted its not worth it!!

And I wish I could base all my info on one block that has gone 116K miles with no issues.

Why the hell did GM even build a 4 bolt main block

Here is a another good link.
http://www.chevelles.com/forums/showthread.php?t=38173

DoubleVision 02-06-2008 07:36 AM

I would go with the Vortec roller block. I stopped using flat tappet blocks a long time ago. If you use the Vortec block make sure you use the timing chain for Vortec engines by Cloyes, if not, a standard timing chain will contact the block, been there done that.

MI2600 02-06-2008 07:40 AM

Curtis, put your block down and slowly back away. He's always right!

CNC BLOCKS NE 02-06-2008 07:50 AM

Quote:

Originally Posted by MI2600
Curtis, put your block down and slowly back away. He's always right!

I am not always right but we deal with a couple hundred blocks a year and VIA emails and phone calls close to 500 about block questions and problems with blocks.

And I am sure we have a box of broken caps and and caps that have walked in there registers because the 2 bolt cpas are not as good as people think!!

I do this type of work for a living every day and I have seen what works and what doesn't and whats DEPENDABLE and whats not.

Big differance when you do this every day and you base your info on more then one block or engine.

k-star 02-06-2008 10:27 AM

Block
 
Before this turns into another 2 vs 4 bolt wizzing match lets all take a deep breath...

It's all application driven. Carl spends alot of time with the dirt track roundy-round guys. They spin engines 5000 rpms off the turns and 8500 plus at the end of the straght-a-way. He gets to see what happens to blocks in the high demands of those applications.

Engines that are used for drag racing are a different deal,,as well as street engines. I have had some disagreements on this issue in the past with Carl. I am thinking ( with out putting words into his mouth) he is only trying to give the guy the best case for his build.

I personally have use many studded 2 bolt applications in 400+ hp street strip 350 engines with zero cap issues, but anything can break. I had one customer split a .030 350 4 bolt block in one cylinder due to detonation. 6 or 8 bolts in the mains would not have saved the engine...It just broke another week link.

It is always better to do what works then what you can get away with. If your good at setting up the tune and pay attention to whats happening inside the engine then at that power level and a street engine the 2 bolt is fine....IMO... a 4 bolt would be added insurance.


Keith

BBCMudbogger 02-06-2008 10:34 AM

Just to stimulate a little more discussion, do rotating assembly harmonics come into play in a discussion such as this? I have been reading these posts and thinking that application may be a factor as well.

Cousin_Joe 02-06-2008 12:29 PM

Thanks for the feedback
 
Thanks for all the feedback guys. I appreciate the different perspectives, and that is why I posted to begin with. My goals are for this to be a street motor, that will be driven daily (for the summer). My '70 Impala is no lightweight racer by any means, and I just figured after a lot of discussion that I would go with a 383 build, as the a little added torque in my heavy '70 might be more fun. I'm looking at a cast crank, and hyper pistons. I'll probably spend more time on the highway than I will burning out, not that I don't want to have some fun. If I didn't want something a little more than what I've already got, I'd be polishing the old stock 350 2-barrel. I was weighing in my mind if I would be farther ahead with the roller block/reusing the lifters than I would be with the traditional hydraulic flat setup all brand new. Thanks! :)

curtis73 02-06-2008 01:12 PM

Quote:

Originally Posted by CNC BLOCKS N/E
Tell the guy in the link I posted its not worth it!!

And I wish I could base all my info on one block that has gone 116K miles with no issues.

I was talking about retro roller cams not being worth it. That thread is about 4-bolt mains.

I never said I only had one engine. I just gave him an example that I currently have. I'm no machine shop, but I've built enough engines that I thought my experience might help the guy out... but if you disagree, feel free to post your own opinion, but there's no need to discredit another person's post or draw misled conclusions from them.

rreruption 02-06-2008 01:31 PM

the roller block def on the 2bolt caps that all depends on how much engine youre going to be running what cr,and cam and what not.I would say take your 4 bolt caps off your other motor and have them machined to fit on your vortec block,get a kit from scat for your 383.If you can 6" rods are better but dont use any less than 5.7" rods.If this is going to be a highway cruiser I'd stick lower cr like about 9.5:1 with an .043 head gasket and a smaller cam like a 270hr magnum cam,A performer intake with a 650 holley vacuum secondary,and headers you dont really need more than a 2.25" exaust pipe.I would suggest a good bowl job,backcutting the exaust valves,and having screw in studs and guides installed.
try..
383ci 9.5:1
Vortec heads
1.52 roller rockers
270HR magnum comp cam
double roller timing chain
Performer or cyclone intake
650cfm holley or Q-jet 750cfm
headers long tube
X-pipe 2.25"
50 series df flowmasters or youre prefence some like the dynomax super turbo


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