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Discussion Starter #1
Installing a 383 stroker kit into my 96 ss and the kit is externally balanced. So what do I do with the original flexplate and dampner ? Can I reuse them as is or do I need a new set. I assume the original flexplate and dampner was balanced with the original motor and would be out of balance on a new stroker kit. What is a 400 style flexplate and dampner which was recommended. Does the flexplate and dampner have a specific weight added (like a ford has 28oz or 50oz weights) I am assuming I would NOT use neutral balanced items with an externally balanced stroker kit. Thanks guys
 

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Are you sure it's externally balanced front and rear? If a crankshaft is externally balanced, then the entire rotating assembly uses both an external balance flexplate and an external balancer damper. These external balanced items have weights added to them in positions indexed to the counterweights of the crankshaft. An internal balance rotating assembly is balanced by balancing the counterweights rather than relying on external weights on the flexplate and damper. For some reason, the LT1 is mixed. It uses an external balance flexplate and an internal balance (or neutral) damper.

For an externally balanced rotating assembly, you need to take the flexplate and damper (with hub) to the machine shop and have it balanced WITH the rotating assembly. They will weigh the rods, pistons, rings and wrist pins to get the bob weight, then use that on each journal, bolt on the flexplate and damper, and then balance it. They drill holes and or add mallory steel to appropriate locations on the counter weights to get it to balance up to a certain rpm. For internal balance, they do pretty much the same, except they don't need the flexplate or damper to do the balance. FYI, mallory is extremely expensive! Also, where they drill the holes and how big they make them can have an impact on windage. A cheap balance job may not be the best job.

Why are you buying an externally balanced kit?
 

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Discussion Starter #4
The stroker kit is sold over the counter as is with all the parts needed and is advertised as externally balanced to one gram. It is a 350 to 383 kit. I could have it rebalanced with the addition of my stock dampner and flexplate but its hard to justify the added expense when the kit has already been balanced. My interpretation is that the 350 flexplate must have a standard weight attached which is the same for all 350's and when they balance the stroker kit at the factory they just add a standard 350 flexplate to the balance machine so that when I install the kit I just add my 350 flexplate and the balance should be the same. This would also allow anyone with damaged flexplate to just replace the flexplate without having to tear down and rebalance the reciprocating parts. The same would go for the dampner. If all the 350 dampners are neutal than I can just add any replacement dampner without changing the balance. So I am trying to verify that, indeed, the 350 dampner and flexplate is the same weight for all production LT1 engines and that those production engines are externally balanced with a weighted flexplate and neutal dampner. If the kit was internally balanced then I would definitely have to find a neutral flexplate and neutral dampner. However, external balance is probably cheaper and that is why the stroker kit companies use externally balanced kits.
 

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It sounds like some of your concerns are with replacement or cost savings regarding the balancer and flexplate. I would take your kit and have it rebalanced with the OE flexplate and OE balancer/hub, so that if you have a failure in the field(on the road) the replacement parts are readily available. this is worth the extra cost at this point for piece of mind later. As for thier specific weights, it has everything to do with inertia and rotational forces, at this point some of those operational theories are a bit further down the road unless your trying for every bit of power possible, and in that case there are other things to get after for the same money.

Chris
 

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The stroker kit is sold over the counter as is with all the parts needed and is advertised as externally balanced to one gram.......
OK.....just stop!

You have no idea what's involved in stroking an engine.....correct?

Don't answer......I already know the answer.

WHAT YOU NEED to do, if you're absolutely set on installing a stroker motor.....Is to buy a completed/finished stroker WITH a set of ported heads and a cam to match.

THEN....you'll need to have a good mechanic install this engine.

Oh yeah.....you should have a PCM with an aftermarket tune ready for install with the engine.

You may need to upgrade your fuel injectors (30 or 36 LBs), throttle-body (52 or 58mm).....headers, cat-back exhaust, ect, ect, ect.

BUT FIRST AND FOREMOST.....you need to buy a complete LONG block!

KW
 
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