lyonsh

Well, it looks like the crankshaft is going to have to be replaced (less expensive to buy a new one than machine the old). So while we're at it, we thought about building a 383. I know you can buy a 383 crank. And since we're replacing rods anyway, might as well buy the longer ones.

Here's my question: Is the 383 crank/rod setup a "drop in" to a 350 block (72 L48 Vette; already bored .030 over), or is there some additional machining required?

I'm kind of embarrassed to ask this, but I've never rebuilt an engine to anything other than stock. So it's never been an issue before.

Secondary question: if we go to a 383, are there any other particular things we should know about that kind/brand of components we should use (rods, pistons, lifters, roller rockers, etc.)?

TIA. :cheers:

gkull

It cost the same for a 3.875 stroker engines which makes 396 ci ruffly. This past year I built two strokers 383 and 393 ci

lyonsh

Thanks, I'll check into that.

Maybe I should clarify my questions: Is any additional machining of the block needed to provide clearance for the rods with the stroker crank?

PatsLs1vette

usually the block has to be relieved alittle bit down the oil pan rail....i believe gkull has some pics of his block where he relieved it.

ScubaJKD

Having just gone down this road I will give you my 2 cents after lots of research. Yes the block will have to be machined for clearance. Don't go with anything less than a 5.7 inch rod. Without going into alot of detail 5.7 rod and longer gives you a better stroke ratio. If you want to save some bucks you can build this up with a 400 crank, GM Pink Rods, and Kieth Black Pistons. Really depends on your application. Also you have to decide if you are going to internally balance. If so you can use a 350 harmonic balancer. If not you will have to use a 400. Hope this helps some

On my motor I decided to step things up a bit. I went SCAT Crank, Eagle 5.7 SIR Lightwieght Rods, TRW Lightwieght Forged Pistons, 10:1 Compression, Edelbrock RPM Heads 70cc 1.60/2.02, RPM Airgap Intake, COMP Cams HD Roller 280H, Roller Rockers, Internally Balanced, Fluidamper, Lightwieght Hays Flywheel. :yesnod:

:seeya


[Modified by ScubaJKD, 9:57 AM 1/3/2002]

72 Stingray

lyonsh,

The 383 in my car now was built using the "old school" method of using the 400 SBC rotating assembly modified to fit a .030" 350 block. I did have to do some minor clearancing on the bottoms of some of the cylinders to get everything to clear but each block casting may be different (mine is a 4-bolt truck block out of a '79 van). No big deal really. The biggest PITA is that you need to assemble the bottom end one cylinder at a time to find your clearance issues, take it apart, clearance the block, clean it (again), and then put it back together. Hopefully you'll get enough clearance the first time and won't need to do it again! As far as the longevity and power of this combo... well, it's been together since 1987 and has had no issues even with not being treated nicely at times. :) Also, I was only 17 and on a very limited budget when I built it. I may replace it with something better in the near future, but for now it will do. If you can drop $1500 on a nice new Scat or Eagle forged 4340 rotating assembly, go for it. http://www.sallee-chevrolet.com/Scat...mbly_Kits.html

The torque levels and street manners between my engine and a comparably built 350 are noticeable. I'm running a 230 degree @ .050" cam with .480" lift and my 383 soaks it up so it doesn't even sound or idle much differently than the original 350 that was in the car previously. Not too intimidating. A good friend had a 355 (with the EXACT same heads, I bought them from him) in his Chevelle with the same cam and it was pretty lopey but didn't have near the same low end. The 383 put my 72 into the 13s without really trying too hard or ever optimizing it for that matter. I hope to do that next summer as one last salute to it for a job well done. :flag

Just my experience...

Good Luck.

BTW... You will need a new flexplate/flywheel and a harmonic balancer for an externally balanced 400 SBC if you go the route I did. You won't be able to use the parts from your L-48. Other than that, everything else should work. Just don't buy parts that are meant to rev to 6000+ because that's not what this motor is meant to do. Also, be sure to check that your .030" cylinder bores give you the proper clearance with the new pistons (if you get new ones). If not, you may need to go .060". 388 anyone? :)

gkull

I'm having a hard time with posting this pic. But anyway I did all my own die grinding for clearance. Shops will do it for a fee. I just don't trust some flunky practicing on my motors when I have so much money in the parts.


This is my 393 4340 forged crank and 6 inch bushed Manley H beam rods internally ballanced fully studded motor. You have to install one piston at a time and rotate it 360 degrees. Or should I say grind till you can. I clearanced @ .040 on the pan rails and you also have to allow for crank end play. If you look at the right picture close the only completed cylinder is #2. Depending upon the rod bolt type is how much clearancing you need. It's not a big deal to do it's just time consuming. You have to wash the motor to clean all the metal fillings out after each hole because you can't nick the crank/bearings/pistons. That's why this motor has light rust. You have to be surgically clean before final assembly.





[Modified by gkull, 10:14 AM 1/3/2002]


[Modified by gkull, 10:14 AM 1/3/2002]

yellow 72

gkull, is there a prize for catching the difference in the two pics? :lol:
Studs in pic one and bolts in two :cheers:

gkull

Yellow 72 - I used the old bolts because your taking apart the bottom end and cleaning after each cylinder. The studs only went in when I was done.

I might add that Chevy small blocks taper wider at the rear. So the most grinding is required at the front passenger side.

That 393 ci stroke is 3.835 with a 4.040 bore 30 over would be the common advertised 391 ci.





[Modified by gkull, 10:26 AM 1/3/2002]

Tomi72

I've got a related question: is there clearance problems with rods and cam lobes when building a 383??? I hope to be building one next spring.

rgds Tomi

gkull

your wise to run what they call small base circle cams. years ago I did a 5.7 H beam rod motor and it required grinding on the bottom of the cylinder bores. I'm not sure if this was just rod design or if the shorter rod caused more angularity.

some guys ding out the oil pan rail for clearance. I just went ahead and bought a 8 quart road racing pan designed for up to 4 inch strokers. another smart investment is a SFI 168 tooth flex and a ministarter.

lyonsh

Thanks for the help guys, this answers my questions really well. :cheers: