383 flywheel part number

[Yukonmuscle]

I've got all my motor parts together to build my vortec headed 383 except for the flywheel. The motor is externally balanced. Does anyone have a part number for the flywheel that I need? The crank is a on piece rear main

 

[Bondo]

Re: 383 flywheel part number

Ayuh,.... Are ya usin' the straight bolt patterned starter, or the staggered pattern,..??

That determines whether ya want the 153 tooth, or the 168 tooth flywheel,...

 

[Yukonmuscle]

Re: 383 flywheel part number

Ayuh,.... Are ya usin' the straight bolt patterned starter, or the staggered pattern,..??

That determines whether ya want the 153 tooth, or the 168 tooth flywheel,...

Not sure what the starter bolt pattern is. I'm reusing the starter off my 2010 5.0l that originally came in the boat. I'd have to look when I'm at home if the year and engine doesn't narrow it down

 

[Bondo]

Re: 383 flywheel part number

Not sure what the starter bolt pattern is. I'm reusing the starter off my 2010 5.0l that originally came in the boat. I'd have to look when I'm at home if the year and engine doesn't narrow it down

Ayuh,.... The block can be drilled for either starter, or both starters, ya gotta know what you've got,...

If the new block ain't the same as yer old block, ya won't be reusin' the starter,...

Who'd ya get the rotating assembly from,..??
What do they recommend for the flywheel,..??

A standard Chevy or aftermarket flywheel, in the configuration, 'n size ya want will accept the coupler used on boat motors,...

 

[Walt T]

Re: 383 flywheel part number

I used the the same flywheel on my stroker that came off the original motor. The balancer is what you need to have and should have come with the kit. Bondo is right though. If you're reusing the starter then its the same.

 

[Yukonmuscle]

Re: 383 flywheel part number

I used the the same flywheel on my stroker that came off the original motor. The balancer is what you need to have and should have come with the kit. Bondo is right though. If you're reusing the starter then its the same.

Both blocks are drilled for both types of starters. Looks like bolts are side by side on the starter. Doesn't makes sense that the factory flywheel can be used without adding more weight to it because it needs to balance a bigger crank throw. The harmonic I have is def weighted differently then the factory one, the flywheel should be too. I sent an email to eagle to see what they recommend for a flywheel but haven't heard back yet. The only info I have found so far says I need a flywheel for a one piece rear main with a 23.4oz/inch weight on it. Found that info on the scream and fly forum I believe.

 

[Scott Danforth]

Re: 383 flywheel part number

usually your machine shop would re-drill your flywheel to get the balance right.

there are also bolt-on balance weights, however I have only seen those used for flex plates. i know on aluminum flywheels, it is usually a 50 oz weight recessed in the back side.

 

[Bondo]

Re: 383 flywheel part number

Both blocks are drilled for both types of starters. Looks like bolts are side by side on the starter. Doesn't makes sense that the factory flywheel can be used without adding more weight to it because it needs to balance a bigger crank throw. The harmonic I have is def weighted differently then the factory one, the flywheel should be too. I sent an email to eagle to see what they recommend for a flywheel but haven't heard back yet. The only info I have found so far says I need a flywheel for a one piece rear main with a 23.4oz/inch weight on it. Found that info on the scream and fly forum I believe.

Ayuh,... I'm surprised ya got the straight bolt patterned starter, the flywheel measures just over 12" right,..??

I ain't seen a small flywheel on a Merc in awhile,... 'cept the 3.0ls,...
Bigger motors turn over Easier with a bigger flywheel,...
Seein's ya need a flywheel, I pop for a new starter(newer permanent magnet type) to match a big flywheel,...

Anyways, Ya need a flywheel of yer choice, that matches the starter ya choose,...
Yer GM dealer can sell ya 1, or any of the Aftermarket on-line shops,...

As for the proper Balancin' of yer motor,.... This is from Eagle products,....

Most Eagle rotating assemblies are sold unbalanced so that the machine shop can choose to balance it however they wish. We do offer most assemblies balanced from us. You must specify you want a balanced assembly in order to get a balanced assembly! If you do not specify, an unbalanced assembly will be shipped.

Because of that quote, you can buy 'bout Any flywheel that fits, as the whole rotatin' assembly needs to go to a Machine Shop to be balanced Anyways,...
They'll either drill holes to loose weight, or add babbit to add weight where ever it's needed,...

The bolt on balance plates Scott mentioned don't work so well on a boat motor, because it moves the flywheel 'bout 1/4" aft,...

 

[Walt T]

Re: 383 flywheel part number

Flywheel is already balanced. You would have known if it wasn't. Its just a round object that is balanced, doesn't matter the crank is bigger. Have it balanced though if you like. Certainly no harm. If it came with a balancer I think that means it's balanced. I've used a few Eagle kits always buy the balanced ones.

 

[Scott Danforth]

Re: 383 flywheel part number

Walt,

the OP has an externally balanced stroker crank. it needs added weight in the balancer and the flywheel

 

[Yukonmuscle]

Re: 383 flywheel part number

Walt,

the OP has an externally balanced stroker crank. it needs added weight in the balancer and the flywheel

I have emailed eagle on Wednesday, no response. Called yesterday morning and got a voicemail at the tech dept. no return call. If I don't hear back by lunch today I will call again. The crank is externally balanced as said before, it is new but didn't come in a kit. I'm sung an eagle crank, scat 5.7 rods and kb d dish pistons. The balancer I'm using is a new pioneer for a 400 crank..... The flywheel needs to be for a 400/383 crank but made for a 1 piece rear main which gm never produced.

 

[Walt T]

Re: 383 flywheel part number

Most of them are. As I said, no harm in balancing the flywheel. My information has been the flywheel is already balanced. If one is using a flywheel or flex plate helps determine which balancer is used. Of course that's not God's word, I'm wrong a lot. Let me know what your sources are. Mine is from Bill at Mountain High Performance. I'll certainly let him know if he is incorrect.

 

[Yukonmuscle]

Re: 383 flywheel part number

Most of them are. As I said, no harm in balancing the flywheel. My information has been the flywheel is already balanced. If one is using a flywheel or flex plate helps determine which balancer is used. Of course that's not God's word, I'm wrong a lot. Let me know what your sources are. Mine is from Bill at Mountain High Performance. I'll certainly let him know if he is incorrect.

I'll post when I finally get an answer from eagle. Thanks for everyone's input so far

 

[Yukonmuscle]

Re: 383 flywheel part number

Finally heard back from eagle. Their recommendation, since I didn't buy a balanced assembly from them is to use the 400 harmonic balancer and to use my factory 350 flywheel. Weight will have to be added to the fly wheel as the 350 flywheel is not weighted properly. Called a few of the engine builders around here and they all send their custom assemblies to the same shop which is about an hr from my city. Sooooo...... Called them and they said the same as eagle for the harmonic and flywheel. They take the crank, rods, pistons, pins, pin retainers, rings, bearings, harmonic, and the flywheel and balance it all. $300 doesn't seem too bad a deal for that.

 

[Walt T]

Re: 383 flywheel part number

Was it more expensive to buy balanced from Eagle? Its my understanding that the companies that sell these kits just weigh rods, pistons, etc and make 'balanced' kits by keeping the parts that all weigh the 'same' according to what standard they use. Having it all balanced by a machine shop is DEFINITELY the way to have it done. I am all for that. $300 for that is a good deal I agree. Even with the fact that most of those parts are already close enough in weight that nothing will have to be done. Balancing a crank with a flywheel on it is not something most machine shops are equipped to do. This is usually done for engines running above 5000 rpm all the time. But I highly recommend a full balance if you can do it. I think its well worth 500 bucks let alone 300 even for a stock engine you're rebuilding.
I always buy the balanced kits even knowing that the marine engine is never running above 5000 rpm. Would you have bought the balanced kit knowing it costs more so you wouldn't have to send it all out? Let us know how that all turns out, ask the machine shop exactly what they're doing, I'm curious. Back in the day building drag boat motors that ran 7-10000 rpms balance was absolutely critical. We measured pushrods and they had to be exactly the same. Each and every cam lobe was measured carefully. Obviously something that expensive has to be done right as you don't get second chances. Drilling or grinding rods and removing tiny pieces of piston best left to the pros. If you see a bathroom scale, drill press, and a bench grinder in the 'Hi Tech Balance Shop' area well maybe the ad that said "State of the art computer controlled balance technology' is taking liberties. If you ask how they calibrate the scale and they show you the owners 400 lb wife as their 'base check weight' well then you can assume that scale has some stressed out springs and maybe you should ask to see records of the spring replacement for that particular model of scale. If they just shrug and show you a stack of 15 new scales in the back room all awaiting their execution by the 400 lb 'check weight' well maybe you should check into a different shop.

 

[Walt T]

Re: 383 flywheel part number

From Car Craft magazine:

Internal Vs. External Balance
Here's where it gets fun. When Chevy engineers pulled out their slide rules and put their pencils to the drawing board in the late '60s to design the 400ci small-block, it meant adding counterweight to the crankshaft to properly offset the longer stroke. There wasn't room in the crankcase to move the crank counterweights away from the crank centerline because the weights would hit the block. Instead, the designers added weight at the flywheel/flexplate and harmonic balancer ends of the crankshaft, creating an externally balanced engine. The 400 is the only Gen I small-block that requires offset balance weights on both ends of the crank. This means that most standard 383 rotator packages use an externally balanced crank that requires a 400-style offset weight balancer and flywheel/flexplate.

While externally balanced engines have survived for decades, heavy external weights are more likely to put a twist in the crank at higher engine speeds. To minimize this, many 383 cranks are also offered internally balanced. This requires Mallory, or heavy metal, to be added to the crank throws to offset the amount of weight normally added to the balancer and flywheel/flexplate. This is a more expensive process, but internal balance does offer durability advantages. Several crank manufacturers offer an internal balance option for 383 stroker packages either as separate cranks or complete rotator packages.


383 Stroker Small Block Chevy - Car Craft Magazine All Pages