I'm building a 383 to drop in my 69 and found a balanced moving assembly, Eagle part B13004L03053. The rub is that this has a 153 tooth flexplate. I don't yet have a starter or a transmission so I've got some flexibility and I'm asking for recommendations.

Background:
I chose the moving assembly based on the engine (L98, being machined now, deck and clearance for 383), heads (AFR 190 w/ 65cc chambers) and behavior: I'm want a mild cam and pump gas, so chose an assembly with 5.7 rods and +18 pistons, which should set me at around 9.6:1 comp ratio.
The Vette is technically a 69 but it's heavily modified with an '80 Dana batwing and formerly had a 427 and manual trans. I'm leaning toward a 5 speed manual, as this is for simple cruising and weekend trips, will never find itself on the strip (at least not with me behind the wheel).

 

Hi. have a similar kit, but internally balanced. With internal balancing, you can run neutrally balanced flywheel/ or flexplate and harmonic balancer.. Also, my sense is you get a better balance. For starter, I bought a PowerMaster 9004. My 383 has more compression than yours, and it turns the motor just fine. it can also be mounted for 153 or 168 teeth on flexplate or flywheel.

 

In an earlier thread I believe you mentioned that you already had the rotating assembly.
If so, you could look into getting it rebalanced with the larger flywheel, if you want to run that.

If you don't have the rotating assembly yet you could buy an internally balanced rotating assembly.

I'm building a similar engine and bought a Scat rotating assembly for my build.
Internal balanced cast steel crank, 6" rods (recommended by the machinist doing my block work) and D-dished pistons for 9.7:1 compression.

I looked on Summit for externally balanced 168 tooth flywheel, all I found were for 2 piece rear main seals.
I assume your block is a one piece rear main seal.

Here are the Chevy Performance flywheels, # 14088648 is for a 168 tooth with a one piece rear main seal.
https://www.chevrolet.com/performanc...els-flexplates

I assume that would be externally balanced, you'd have to check.

 

I did; I'd bought a ton of stuff from my neighbor, a former builder for racing, and that included a SCAT 383 forged crank with forged pistons and 6" rods. I was going to use those but then with some research realized that that would force me into an aggressive cam and piston slap when it's cold, neither of which I want. So choosing an assembly with hypereutectic pistons and 5.7 rods.

As I understand it, going with the 383 requires an externally balanced assembly; am I mistaken?
Regardless, is there anything wrong with using a 153 tooth flywheel? I thought that this just constrains the starter choice. Yes?

 

My 383 one piece rear main Eagle kit with internal balance is https://www.summitracing.com/parts/esp-b13055l03068

 

Sorry, after I hit "Post Reply" I realized I probably didn't answer your question regarding the 153 tooth flywheel.

I did my research a few months ago, then promptly forgot most of what I learned once my parts were ordered.
You can find internally balanced 383 rotating assemblies, mine from Scat is. However I don't know about with the pistons and rods that you want.

As far as the flywheel, I don't know why a 153 tooth wouldn't work, I went with a larger flywheel for the larger clutch.
I believe the LT-1 came with a smaller clutch, I suspect for less rotating mass and quicker revs.

 

I would use a larger chamber and a flat top piston before I used a dish and a small chamber. I just built a 383 with 72cc chamber and single valve relief pistons for 10.4 to 1 compression......which is fine on pump gas.....this setup had the piston .010 in the hole and a .028 head gasket for .038 quench....right on the money.....it was an Eagle Assembly too. No worries on the 153 fleaxplate.....that is why most Mini High torque starters have to sets of holes. I use the CVR 5323...IMHO the best starter on the market bar none.
All the new aftermarket heads have the fast burn heart shaped chamber pioneered on the L31 Vortec.......they are super efficient....so much so that you make the same power with 3-4 degrees less advance than the old school "D" chamber......it is also very detonation resistant......
Point is you can run more compression these days.....I like building in max compression for the application becasue it makes for a crisp, torquey, good sounding engine....and leaves room for cam changes in the future (You wouldn't believe how many want a bigger cam after getting spec'd a "mild" street cam)......
I built this 383 for high average torque and it runs a healthy cam 230/236@.050...but a small Dart 180 head and Performer EPS intake with the divider milled and a 750HP Holley........it will sound awesome and have enough torque to pull hell off a cross....all on 91 octane.....
My 12 year old Silverado has a tiny cam and 10 to 1 compression and runs very well on 87 octane.......it is all in the chamber and the tuning......

Jebby