I posted this question over on the general 4x4 forum and it kinda took off into a "Ford" direction. I thought I'd try again here. The subject was briefly hit on the LCML.

I am want to gain some more low end torque or lugging ability on my Chevy SB 305 and was curious to know if I could use a heavier flywheel. Anybody ever gone to a heavier unit? I am running the sbc in a fj40.
I know the Toyota f, 2F engines have a monster sized flyweel on them to help produce that low end torque. Toyota must know something. Do different Chevy truck applications have heavier flywheels than cars? Can I heavier flywheel ? My engine came out of a early 80s Chevy car. What would the pros and Cons be? Any suggestions appreciated.

bennett

The flywheel on my F motor weighs a lot more than a stock chevy one. Although I am not sure of just how much heavier.

Pros: More low end torque, less stalling (Due to more weight spinning down there, making it less likely to stop spining)

Cons: Slower reving, more wear on start (Or so I am told)

I also have a 305 (darn thing won't quit) I use the 168 tooth flywheel which is larger and heavier than the 153 tooth flywheel.
It will help a LITTLE to keep your engine from stalling. I also use a 12 inch clutch (from trucks) as compared to the 10.5 inch clutch that most cars have.

I had to buy a different starter when I swapped flywheels...this turned out good cause it cost less and worked better:)

The heavy flywheel is one of the main reasons I like the 2F on the trail! There's been plenty of times when I've reached for the ignition switch thinking I've stalled the motor when ...chug, chug, chug; it kicks back to life again.

Here's a link to a guy who made his own inertia ring:
http://home.off-road.com/~ne4wi/docs/tech_inertia.html