Gen IV to SM465 in a K5

[Oilbrnr]

So I'm the second owner of my '77 K5. The original owner put a Goodwrench 350 in it back in '91 and it now has ~40k documented miles on that motor. In his later years, he didn't drive the truck much, and the last two or three years it just sat. (he went into a retirement home). Valve stem seals are leaking bad, clutch chatters some, TO bearing just started to whine, and the original Quadrajet needs shaft bushings, etc. In other words, the time has come to do something!

I have a 2007 4.8L that I would like to swap in. I'm keeping the SM465/NP205 for my own personal reasons. A tranny swap is not an option.

Is Advance Adapters the only source for a flywheel/PP kit as far as anyone is aware of?

http://advanceadapters.com/product/3751/712500M.html

Thanks for any input!

[DirtyLarry]

Well, I don’t have the answer but I would love to know what exactly is in the AA kit for $621.00!?

I don’t have any swaperoo experience with the late model LS small blocks but I suspect all you need is a 4.8L/6.0L manual trans flywheel then use the clutch and pressure plate spec’d for your original 350.

For my 8.1L conversion I used the 8.1L flywheel and the same Centerforce clutch I have had behind my old 350, 454HO and now 8.1L. Not the same part number of clutch, but the same exact clutch and pressure plate behind 3 different engines.

To make the ‘78 pressure plate work on the 8.1L flywheel I had to remove a few dowel pins that were pressed into the flywheel then open the mounting holes on the pressure plate a little larger to accommodate the larger metric mounting bolts. I would suspect a Gen III or IV small block would be similar.

[Oilbrnr]

Originally Posted by DirtyLarry

Well, I don’t have the answer but I would love to know what exactly is in the AA kit for $621.00!?

LOL, well here is the kit BOM:

No. Qty Part No. Description

1. 1 711500M 168 FLYWHEEL
2. 6 716141A 11mm FLYWHEEL BOLTS
3. 1 LC165552 CLUTCH ASSY. 11" P.P.
4. 1 716155 PILOT BUSHING SPACER
5. 1 716328 T/O BEARING (new style)
6. 5 720028 10mm X 1.5 BELLHOUSING BOLTS
7. 5 720038 10mm LOCKWASHER (for bhsg. bolts)
8. 6 723761 XRP DOWEL BOLTS (pressure plate)

So I guess roughly $400 of the kit is for the custom flywheel. I'm not clear yet which Centerforce PP and disk they are using, but that alone is around $250+.

I guess I could call Novak too and see what they might offer, can't find anything specific on their site unless I'm just not seeing it.

[DirtyLarry]

Whoops, I missed their BOM.

I doubt there is anything custom about that flywheel. Unless, of course, they removed a few dowel pins like I did and call it a custom. Call around and find a used 4.8L/6.0L flywheel. I bet you can bolt your existing clutch and pressure plate right on to it and reuse your release bearing as well. Heck, even the new 8.1L flywheel I picked up was just a tad over $100 from a GM dealer.

No sense forking over big bucks to AA or Novak if you don’t have to.

[Oilbrnr]

Well, this is what has me wondering though:

GENERAL INFORMATION:
Since Vortec flywheels only fit a Vortec block and the engine crank is recessed .400”, there are a couple of things that must
be addressed. Usually our bellhousing kits include a new pilot bushing. A problem occurs because of the 1.090” diameter that
our bushings fit into on a standard GM is now .400” closer to the back of the block, creating a pilot bushing engagement
problem. This kit comes with a pilot bushing spacer for the manual transmission applications. The spacer in this kit sets the
pilot bushing in the correct location. NOTE: The grove on this bushing must be facing out when installed into the engine
crank.
The second issue is the flywheel. The flywheel in this kit only fits the recessed crank and bolts to the crank without a
flywheel spacer. There are some Vortec blocks that do not have the recessed crank. This kit will not work on these blocks.
One block that we know of is the 6.0L with cast iron heads and the 4.8 engine coupled only to a stock manual transmission
in 1999 to 2003. A custom flywheel would have to be made to work on these block.
The pressure plate and clutch disc are also included in this kit. These components are specifically designed for the Vortec
engine. The bolts have also been included to allow proper alignment of the pressure plate to the flywheel.
The release bearing in this kit is a custom bearing. When coupled to a stock transmission, the Vortec engine used a internal
release bearing. Our full bellhousings are not compatible with the stock internal setup. This bearing design is manufactured
to replace the internal bearing with a conventional bearing setup. Do not use any other type of release bearing with this
conversion. Premature clutch failure could occur.

[Oilbrnr]

dupe post

[69MyWay]

Originally Posted by DirtyLarry

Well, I don’t have the answer but I would love to know what exactly is in the AA kit for $621.00!?

I don’t have any swaperoo experience with the late model LS small blocks but I suspect all you need is a 4.8L/6.0L manual trans flywheel then use the clutch and pressure plate spec’d for your original 350.

For my 8.1L conversion I used the 8.1L flywheel and the same Centerforce clutch I have had behind my old 350, 454HO and now 8.1L. Not the same part number of clutch, but the same exact clutch and pressure plate behind 3 different engines.

To make the ‘78 pressure plate work on the 8.1L flywheel I had to remove a few dowel pins that were pressed into the flywheel then open the mounting holes on the pressure plate a little larger to accommodate the larger metric mounting bolts. I would suspect a Gen III or IV small block would be similar.

Can you tell me if your flywheel had a ridge in the face where the clutch cover bolts on - so that the face of the flywheel wasn't smooth all the way across?

I'm putting a 8.1 in a project vehicle mated to a Richmond six speed - which is just like a Muncie 4...etc. The flywheel Raylar sent me for my motor has the ridge (face isn't flat) and I' can't come up with a traditional clutch application.

TIA!

Chris

[DirtyLarry]

Originally Posted by 69MyWay

Can you tell me if your flywheel had a ridge in the face where the clutch cover bolts on - so that the face of the flywheel wasn't smooth all the way across?

I'm putting a 8.1 in a project vehicle mated to a Richmond six speed - which is just like a Muncie 4...etc. The flywheel Raylar sent me for my motor has the ridge (face isn't flat) and I' can't come up with a traditional clutch application.

TIA!

Chris

Hello Chris,

Welcome to the board. Yes, the 12582964 8.1L flywheel that I used is perfectly flat. As mentioned above, all I had to do was remove the unneeded dowel pins and expand the mounting holes in the pressure plate to accommodate the larger metric bolts in order to reuse my existing clutch and pressure plate. Been running this now for 4,000 miles without a single issue.

Call Ray or Larry and see what the story is with the flywheel they sent you or if they have a recommendation for a clutch. It almost sounds like they may have sent you a marine flywheel.

The 12582964 flywheel is the part number that GM lists for a replacement for my 2001 Silverado HD with an 8.1L. The flywheel bolts are GM pn 12563485. Also used a 8.1L specific pilot bushing but didn’t document the pn.

Here is a not so good picture of the rear of the engine. Too bad I didn’t get one without the clutch and pressure plate on there.

If you are going with the MEFI-4 engine controller, I don’t recommend it. Converting mine over to OBDII with a PCM32 this winter. I am tired of fiddling around trying to program this stupid thing.

Good luck with your project.

Don, sorry your thread got jacked.

[69MyWay]

Cool - and thanks for letting jack the thread a bit.

This is a MAJOR relief...and I would agree I have by some strange reason a marine flywheel.

I learned Centerforce makes a kit DF612909 specific for the 572 - which uses the same flywheel. Perhaps, the dowl holes and bolts would not need to be modified on that one.

Originally Posted by DirtyLarry

Hello Chris,

Welcome to the board. Yes, the 12582964 8.1L flywheel that I used is perfectly flat. As mentioned above, all I had to do was remove the unneeded dowel pins and expand the mounting holes in the pressure plate to accommodate the larger metric bolts in order to reuse my existing clutch and pressure plate. Been running this now for 4,000 miles without a single issue.

Call Ray or Larry and see what the story is with the flywheel they sent you or if they have a recommendation for a clutch. It almost sounds like they may have sent you a marine flywheel.

The 12582964 flywheel is the part number that GM lists for a replacement for my 2001 Silverado HD with an 8.1L. The flywheel bolts are GM pn 12563485. Also used a 8.1L specific pilot bushing but didn’t document the pn.

Here is a not so good picture of the rear of the engine. Too bad I didn’t get one without the clutch and pressure plate on there.

If you are going with the MEFI-4 engine controller, I don’t recommend it. Converting mine over to OBDII with a PCM32 this winter. I am tired of fiddling around trying to program this stupid thing.

Good luck with your project.

Don, sorry your thread got jacked.

[jays68yak]

Not to bring up an old thread...but only cuz I came by this in a search. Ive done several 8.1 swaps in my personal trucks. For the one that has a sm465 behind it I got a stock 427 flywheel. Since those were internally balanced like the 8.1 is. The flywheel was something like $30 at kragen. Used the same clutch plate and pressure plate I had behind my 454. No issues 2 years later. The 8.1 is different from the 4.8/6.0 and other LS series engines. It doesnt have a lot of the changes that they do, IE crank offset and what not. Just thought I would toss out my 2 cents.