I am looking to put a ZZ 383 in my 95 Z71 350 5spd. First off, I'm running a Holley 670 TBI @ 14psi and am wondering, new custom chip aside, if it will be adequate. Second is, which flywheel will I need, as it comes with a flexplate. I'd like to keep the 12" clutch. Also, will there be any other modifications necessary for the fit? I heard the exhaust ports were larger too, will I need to change the manifolds/headers to something beside the Edelbrock T.E.S. I have? Thanks.  

Lots of good news, you already are prepared to reprogram the computer so you know that's coming.

You will require an intake which can be a standard high port or Vortec bolt pattern GM recommends these; P/N 12496820, P/N 12366573, 12496822, or 10051103.

Your existing flywheel bolts up.

You shouldn't have any problems with your Edlebrock headers.

Bogie  

Good, thanks for the reply. I am currently using an Edelbrock performer TBI intake and the specs on that engine says it has both Vortec and non Vortec intake bolt patterns. I am assuming that this is ok to reuse?

As for the flywheel, I know it bolts up, but are you saying that it is the right one for the balance of that motor?(just clarifying)Also I'm looking to replace the flywheel, so a stock one is ok or should I get an aftermarket one? (part #?)

And the Holley 670 is fine right?

Thanks again for all the info, this was the best source so far and I've been looking all day!  

Welcome to the 383 Twilight Zone, there are 383s and there are 383s, some need external balance like the old 400, some don't, and some sort of.

Your's is a sort of, but that's OK as it's the same "sort of" that 350s need since the inception of the one piece rear seal.

Your old 350 flywheel, for a one piece rear seal, is what's required for your GMPP 383. Don't forget to put a pilot bearing in the end of the crank. You should probably have it (the flywheel) skimmed as well to put a fresh friction surface on it.

Where the Twilight Zone comes in is where people get confused because of so many ways to build a 383. The collective "you" have to know how the 383 you own came to be from which parts.

- 383's built from 400 cranks all use 2 piece rear seals and require 400 style dampers and flywheel/flexplates for external balance. Unless you have them internally balanced, this you better know before assembly!

- 383's built from purpose built aftermarket cranks require that you carefully keep track of what you're buying. Some are essentially new small journal 400 shafts. These need to be balanced like old turned 400 shafts. Some are made as 2 piece seal 383 shafts but balance can be a dogs breakfast with some balanced to external 400 specs and others to internal 350 specs and some probably in between.

- The one piece seal 383 shaft usually is like the one piece seal 350 engine shaft where it's almost but not quite internally balanced, it's just slightly off because the one piece rear seal knocks off a chunk of counterbalance from the end of the shaft. So these require a unique flywheel/flexplate The flywheel you have makes up that difference just as it did for your 350.

However, there's been plenty of reports over the years about shaky engines that were either home builts or came from less than reputable builders or the final installer didn't read the fine print, what-ever.

All of the above is why you'll find what seems to be conflicted information and confused people.

Bogie