383's and drives
 

Guys,
Repowering my 1986 SBC/Alpha Formula using a couple of stout 383's. The engines require a 8" 400 damper and was equipped with a balance plate for rear crank. They are 2pc rear seals. I'm having a difficult time locating a suitable flywheel for this setup. Does anyone know a proper mercruiser part number for such a setup eliminating the balance plate? I would be bolting up to bravo coupler and using the 86 bell housing. Thanks in advance for any knowledge.

I don't have a hard and fast answer for you but...sounds like you have a pair of externally balanced 383s set up with 400 cu in style cranks. You might have luck with a "Big Block" fly wheel. I believe 396/427/454 engines are externally balanced and might solve your problem.Keep in mind that you don't necessarily need a "Mercruiser" flywheel to get this done. Check with Michigan Motorz and others for what you need.

Good luck and keep us posted on what you use.

Thanks and I will give them a call tomorrow. I was told something similar.... I was also told Mercruiser flywheels are essentially GM truck units. The key is finding the right one. I know the guys at Michigan are pretty knowledgeable and can probably get me in the right direction.

As far as I know balance plates, they are for use with a neutral balance flywheel....so, the motor is correctly balanced.

The plate is mounted between the crank and the flywheel.

Check with your builder...but I believe what I said above is how these are to be used.

Plate kinda looks like this, right ?
http://www.northernautoparts.com/Ima...6690_thumb.jpg

BTW: To be able to get rid of the balance plate, you'd have to have your engine balanced by a pro. Therefore, time to take the motor apart to weigh everything.

yes, that's the plate I have. From what I understand, your correct. It's used to enable a neutral balance fflywheel; typically the older 350's......However, I'm also thinking a 400 flywheel would work since it isn't neutral and would negate the need for the plate. More research to do.....

do not use 454 flywheel on small block ext balance engine.you need a 400 truck clutch flywheel. the 454 flywheel is balanced way diff than the 400. i (thought i) bought a 400 flywheel. it was 454. my bow rails vibrated back and forth about 6 inches at idle the engine was so far out of balance. i think the flywheels can be had on jegs. the balance plate from what i hear is pretty close to the stock 400 flywheel.

Thanks for all the info....problem solved. While mercruiser uses several versions of flywheels on the 5.7's, I have one the most common sizes. 222-9520. It is a 168T 14" gm unit, 14091599.

As we know, 383's can be internal or external balanced. Since my engines are external, the plate can be removed providing a correctly weighted flywheel is used. The plate is only used to allow a neutral wheel. After lots of research, GM 3986394 is the proper unit to eliminate the plate....

Ayuh,.... If that's GM's flywheel for a 400 SBC, standard clutched transmission, you've got the Right one,...

Our couplers bolt onto the pressure plate bolt holes,....

Btw,.... I doubt that Bravo coupler will fit under yer flywheel cover,..... Use the right Alpha coupler,.....

The coupler ain't the weak link, it's the Alpha gears, 'n shafts,....