I know many of you have a 383 in your LT1. I was wondering will the stock flywheel bolt up to it or do you have to get a new flywheel? I see that most kits come with a flex plate but what if you have a M6?

thanks
matt

 

This would be best posted in the DriveTrain Forum, transfering.

 

The flywheel doesn't "know" how long the stroke of the crank is. IOW, choice of flywheel has nothing to do with the motor being a stroker or not. The only relevance I can think of is wrt balancing. A stock flywheel/flexplate has a small counterweight. If you are getting a new rotating assy it and want to reuse the stock flywheel/flexplate the rotating assy will need to be balanced against the counterweight. The counterwieght can be removed and the whole assy, neutral balanced as an alternative.

Rich Krause

 

Im not worried about the balancing aspect of it. I want to know if the stock flywheel will bolt up tyo the 400 crank? If not where and how much am I looking at?

thanks
matt

 

The LT1 uses a one-piece real seal. The crank is different from a 400 crank. In the "old days" we used 400 cranks in a 350 block and with a 30 overbore, voila, a 383. If you are stroking your LT1 you will need a 3.75" stroke crank with a one-piece rear seal. In that case, your old flywheel should be fine.

Rich Krause

 

Then what if the block is using a 400 Nodular iron crank? in a LT1 block with a 1 piece rear main?

matt

 

You can't. AFAIK, all "400" cranks were 2-piece rear seal.

Rich Krause

 

Here is the link to it...He told me it has a adapter on it to make it a 1 piece seal. http://web.camaross.com/forums/showt...hreadid=273376

HELP...matt

 

Matt:

Production small-block V8 and V6/90-degree Chevrolet crankshafts were redesigned in 1986 to use a leak-resistant one-piece rear seal. The diameter of the crankshaft flywheel flange was reduced to fit this new seal. The engine block, oil pan, pan gaskets, and flywheel were also redesigned to accommodate this one-piece seal.

Crankshafts designed for one-piece seals have a smaller flywheel bolt pattern than pre-1986 production cranks. All small-block and V6/90-degree cranks which use a one-piece seal require a counterweighted flywheel for proper engine balance.
Unmachined crankshaft forgings and most heavy-duty crankshafts (except P/N 14096036) use pre-1986 two-piece rear seals. These cranks can be installed in late-model blocks which are machined for one-piece seals by using crankshaft seal adapter P/N 10051118.

10051118 Crankshaft Seal Adapter
A leak-resistant one-piece rear main bearing seal was introduced on production small-block V8 and V6/90º Chevrolet engines in 1986. Crankshafts in these engines were also redesigned to accommodate the new one-piece seal design. This adapter kit allows you to install an early-style crankshaft designed for a two-piece seal in a block which is machined for a one-piece rear seal. This seal adapter can also be used when installing a heavy-duty crankshaft in a cast iron Bow Tie small-block or Bow Tie V6/90º block machined for a one-piece seal.

Technical Notes: The crankshaft seal adapter kit includes a two-piece aluminum seal retainer and related hardware. It does not include a gasket and two-piece seal; use pre-1986 two-piece rear seal P/N 10121044, retainer gasket P/N 12555714, and dowel pin P/N 9441003. The large outside diameter of the seal adapter requires a 1986 or later oil pan and gasket set. See the Chevy Power manual for installation instructions. Hex bolt P/N 10051121 and washer are used to hold the two halves of the adapter together. Bolt P/N 10051123 is used to hold adapter to cylinder case.

You can use a 400 crank in an LT1 block with the adapter, but the flywheel flange will still be the wrong size to use a flywheel intended for a one-piece rear seal crank.

Rich

 

so what this means is I have to get a flywheel for a 400 crank with a 2 piece rear main? Is there a certian size I need and will my spec stage 3 clutch mate up to it? I know it is a 168 tooth flywheel. So do I have that right?

thanks
matt

 

The stock LT1 flywheel/flexplate has 153 teeth on the ring gear and a 12.75" external diameter. 14" flywheels found on early small blocks and big blocks have 168 teeth. I believe the spacing of the teeth is the same.

Call you clutch manfacturer to be sure you are getting a flywheel that will work.

Rich Krause

 

Hey rich...you think this flywheel will work?
http://cgi.ebay.com/ebaymotors/ws/eB...category=33732

matt

 

No, I think it's a 14" flywheel.

Rich Krause

 

so what size will I need to get?

thanks
matt

 

12.75". 153 teeth with the bolt pattern to match your crank.

Rich