Tom_K

Thanks to all who helped me determine that my 427 had the wrong flywheel (had a 454)

So I will be ordering a new one. Question: What do I get and or should I go lighter?
My Car:
68 Vett conv. 427/390HP -(has hotter cam) 4.11 rear, currently swapping to a Tremec 5-speed with overdrive.

I am inexperienced with big blocks.
On high revving 4 bangers in light weight cars, light flywheel are great.

On the 427 is a bit lighter better?
Also - I see flywheels ranging from $89 - $500
Is there a best way to go?
Looking for fun sport and spirited driving. The car will not be raced and be driven frequently in the summer.

Thanks!

TK

naramlee

I have always run under 3500lbs, and have always used lightweight aluminium flywheels, from 350, LS1, LT1,302 and 408w... it's your preference but they all seemed to work just fine for me and my car's weight

I've always felt the 10:1 ratio of cubes to weight was fine with lightweight drivetrain, and I love the sound of a snappy rev

OldCarBum

I asked this same question on the forum a couple of months ago and got a full bag of mixed comments.
I'm sure you will, but if not search for the thread I posted which is full of good information.
I ended up purchasing a 24 pound, mid weight, billet steel flywheel from McLeod Racing for my 496.

jackson

Before you just slap a 427 flywheel on it ...
Suggest In lieu of irrefutable verification from builder-machine shop...

Suggest pull heads / view crank and measure stroke to verify if crank is 427 (3.76") or 454 (4") stroke.

? Maybe they put a 454 crank in a numbers matching 427 block?

But whatever ... Pretty sure Perfection Clutch and/or Pioneer manufacture an iron 153T flywheel weight just under 16lbs.Yes flywheel Not flexplate. And under $100. I've used one in a 2 pc rms sbc 355" circle tracker ... not sure but maybe same neutral flywheel fits pre-70 BBC (427)?

OldCarBum

You will also need to know if the motor is internally or externally balanced.

Big2Bird

You should be able to tell pulling the pan, right guys?

blue427

the balancers are different on an internally balanced and an externally balanced engine.find a pic of them and you've got your answer.

derekderek

Yes, but if someone used the wrong flywheel, they could have also used the wrong balancer. Also as mentioned it could well be a 454. I would think a 427 with that flywheel would vibrate at idle rather badly. And, if a 427, you could use a 350 flywheel. I would use the heavy standard 89 buck version. Light flywheels are for road racing, mainly.

Hemi John

Or.... if it does have a 4" stroke crank (454) and had the right flywheel but 427 balancer which could be causing vibration.

You need to check the back of the harmonic balancer for an external weight and either talk to engine builder or pull oil pan and confirm stroke and balancer/ flywheel needed. blocks on 427 and 454 engines are the same. Easy to swap crank for extra cubes and power if engine was rebuilt.

Just playing a guessing game without knowing crankshaft stroke

TimAT

Light flywheel= builds RPM quicker. Less inertia to get things moving.
Whatever you decide on for a flywheel, get one that's SFI approved. Might be a little more cash, but the quality is better-

Vette5311

derekderek

at this point, I don't even think I would trust the builder. He might have thrown a 454 together and told the guy it was a 427 because that's the parts he had. If that's the case, he's going to tell you the same thing even if he knows different. Drop the pan measure the stroke.

Sunracer

with 4.11 gears you won't have trouble launching and a high rev cam will make it fun to drive with a lighter flywheel

cagotzmann

I switched my ZZ383 from a steel to light weight Alum Flywheel. I gained 1/4 mile time plus extra MPH @ the end. So the car performed much better but at a cost.

Since I have a T56 Magnum 6 speed with a Twin disc clutch I now have some gear rattle noise @ 2200-2500 RPM. This is because the twin disc clutch doesn't have vibrational dampeners in the clutch discs, and with a light weight flywheel you hear gear rattle noise. If you have vibrational Dampeners in the clutch discs you shouldn't have a problem. The twin disc setup was to reduce or replicate a C6 clutch pedal feel.

derekderek

Okay, here's a thought. This engine has been rebuilt. Get one of those $10 eBay borescopes. They some of them USB into something some of them Bluetooth to your phone. And then take out a spark plug that stick it in there and see if you can read the part number on the piston. And that'll tell you if the 427 or a 454 piston. With the different pin height they're not interchangeable. And if there's nothing there, you can drain the oil and stick it up through the bottom and see if you can read a part number on a piston from underneath.

derekderek

That's right, this engine is not in the car. They just take off the damn oil pan.

Surfer69

One issue I had with lighter flywheel is they are usually thinner than standard. So you have to watch your TO brg and pivot ball setup and make sure it will work. I had to go back to thicker since there is not a lot of adjustment in the stock vette clutch linkage. Don't know about Tremec setup though. My .02

naramlee

they make adjustable pivots to fit w/e height you need, just search adjustable shift pivot for X tranny but iirc they are mostly the same

OldCarBum

On the McLeod mid weight steel flywheel, they take a standard 33 pound big block flywheel and machine 9 pounds of steel off the middle of the flywheel to remove the weight so everything is the same.

drwet

I ran into this problem when I was building my last engine. I decided to go with a mid weight steel flywheel. Turns out the manufacturer just milled 9 lbs off the face of the flywheel. The result was my clutch disc interfered with the flywheel bolts. I wasn't about to change the clutch and pressure plate, so I returned the flywheel and bought an aluminum flywheel with a steel insert. It checks in at about 17 lbs. Its great but it does take a little getting used to. You have to carry just a little more RPM off the line, and yes, I have stalled it a couple of times. Very embarrassing when it happens at a busy light. I have a 427 small block so I have plenty of torque. I would not use the lightweight flywheel with a much smaller engine or in a heavier car.