Flywheel/clutch/presure plate compatibility issues. Help needed soon.

[AyWoSch Motors]

As some of you may know, I got a new 350 for my 86 Seirra. The one last thing keeping me from putting it in is the debacle I'm having with the flywheel and related parts. And I'd like to get/order parts, soon so I can maybe get it this weekend or thereabouts.

So it originally had a 305, and im upgrading to a L98 350. Problem one, is the truck originally had an 11in clutch, and the clutch it says I need for an 86 with a 350 is a 12in, and the guy at the parts store said I'd be an idiot to run that 11in clutch with that engine.
So my question there is, do I get a new 11in clutch, and stick it on my old crap, and hope for the best, or do I get a new 12in clutch and pressure plate and hope it fits my flywheel.
I wouldn't mind upgrading to something bigger as long as it fits.
That brings up the second question, will a 12in clutch fit my flywheel I have.
I had the original 305 flywheel and pressure plate, and they're still in good shape, but the 86 truck 305 flywheel wouldnt fit the 86 corvette 350. The center bore size in the crank snout and the bolt pattern was too small. So I looked my parts pile and stack of flywheels, and found 2 that fit the engine, but only one had the right bolt pattern for the pressure plate.
Problem with that is it's really rusty, so I'll have to get it resurfaced or buy a new one.
That brings up the third problem which is price and what to buy.

To resurface the flywheel I have, itll be $55-60. To just buy a new one on summit that says it fits itd only be $77-80 and brand new. But then what am I looking for for specifics. How do I know itll fit my crank, and how do I know itll fit a 12in clutch.
Then theres that side if it. To buy just an 11in clutch, its $108.99 at the parts store, but also at the parts store, yet a new 11in clutch, pressure plate, and bearing is like $120ish, but it's only $98.99 to get a new 12in clutch, pressure plate, release bearing, pilot bushing, and alignment tool. Way better deal, that I'd be happy to do, but I cant unless I know it would fit what I have.
I think best value and quality would be to get brand new everything so I dont have to worry about longevity, but I just need to know exactly what I'm looking for, what size, and what specs. I may be stuck with the old stuff I have, but that's okay too.

It's a half ton, short bed, 4x4, with a Corvette L98 and a SM465 muncie. Its not going to be hauling alot, its not a racecar, just a daily.
What would be best?
Thank you.

 

[AyWoSch Motors]

@bucket @SirRobyn0 @Blue Ox
I know you guys are all real knowledgeable about those sorta things. (As well as many others, just throwing names out there).



And for reference, the flywheel that I have that fits, after I sanded some rust off.

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And some things I was looking at...

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[SirRobyn0]

@AyWoSch Motors I'm not really knowledgeable in the differences between the 11 & 12 clutches, but this is what I would do.

At the shop we virtually never resurface flywheels for the exact reason you just stated, a new one is barely anymore $$ than a resurface, so if it were me I'd get new flywheel and clutch. I'd get the 12" stuff and run with that, provided that the tooth count for the starter is the same on both flywheels and as few as I know they will be. I'd check over fitment when the parts arrived but AFAIK the bellhousing are all the same so I think it would all be interchangeable.

IDK, really how helpful that is but it's what I've got. Hopefully one of the other guys comes along with better knowledge in this area.

 

[bucket]

So the Corvette 350 is probably made in '85, due to the large flywheel pattern and it should have the 2-piece rear seal. That flywheel you have should be fine, as long as it's neutrally balanced like a 265-350 small block takes.

11" clutch will be fine unless you plan to tow a bunch of weight around all the time.

 

[bucket]

Also, I've always had good luck doing a home "resurface" on a flywheel that isn't in too bad of shape to begin with. Do I recommend it? No. But it's what I do for my own stuff and it has been fine.

 

[SquareRoot]

I went thru this recently when I converted from auto to my nv4500. After much back and forth I ended up with an 11 inch clutch, which was spec'd by AA for their bell housing. The 12 inch was overkill and more trouble than it's worth. Same with flywheel. I just bought a new LUK from Summit and was done with it. Been running smooth as butter for 6k miles now.

 

[AyWoSch Motors]

Well thanks for the suggestions guys and for helping to reassure me that I was thinking in the right way.
I went out today to O'Reilly's, and bought a brand new flywheel and a new clutch/pressure plate kit which also came with new release bearing, pilot bushing, and alignment tool. Turned out to be way cheaper than what I was going to do.
I was able to return the other clutch, the release bearing, and the pilot bushing that I has bought ahead of time when i was originally going to use my stock parts, so i made my money back on those. The whole kitten kabootle today cost only $193, and i got all brand new parts.
All set for 12in clutch (which might grab a little tiny bit harder, which would be okay), all fit together and with my engine, and all properly specced for a 350 in a half ton.
I'm happy I went with all new.
Should all work out, I don't see why it won't, but we'll see.
I'll let ya know either what goes wrong, or how well it works.

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