Will a SM465 hold up to an 8.1l?

[rs74]

I am picking up an 84 K30 SRW and wondering about an 8.1/SM465/205 setup. I like the fuel injection but want something more than a 454. So for me it is either look at the 8.1 or a Cummins.

[MalibuSSwagon]

DirtyLarry ran that combo for years in his K10 before doing the NV4500 swap. So assuming your SM465 is healthy I'd say do it.

[americanmusc1e]

Keep in mind that the SM465 came in up to 2-ton trucks from the factory.

If you ever had one of these transmissions apart you'd understand. Just the mainshaft alone weighs around 70lbs. I heard somewhere that it's "official" torque rating is 465ft-lb. Not sure if it's true or not, but I had mine behind a 450 ft-lb 383 and it didn't flinch. You'd have to spend a lot of money on a clutch that will hold 750+ ft-lb to break the SM465.

You can break the roll pins holding the shifter in place though. The SM465 likes to be shifted with steady pressure. Don't expect it to shift fast, and for sure don't just try to jam it in a gear. I opened mine up to check it's condition before mating it to the 5.3, and i found a pile of what I thought was roller bearings in the bottom of it. Turns out they were roll pins. Whoever had it before me probably kept breaking them off and then just knocked them out to the bottom of the transmission.

[slotard]

You might also consider a 502 for the engine, the 496 might have a little advantage down low but the 502 should breathe better up top (it's a larger bore and shorter stroke). I'm not saying the 502 is lacking in torque though. Or you can always put a 496 crank in a 502 for 540...

[americanmusc1e]

Originally Posted by slotard

You might also consider a 502 for the engine, the 496 might have a little advantage down low but the 502 should breathe better up top (it's a larger bore and shorter stroke). I'm not saying the 502 is lacking in torque though. Or you can always put a 496 crank in a 502 for 540...

Considering this is in the LSx swap section, I'm guessing he is referring to the late model Vortec 8100 8.1 motor. Which, according to wikipedia:

"Other important differences between the Vortec 8100 and older Big Blocks include a changed firing order (1-8-7-2-6-5-4-3), a new 18-bolt head bolt pattern, longer connecting rods, different symmetrical intake ports, different oil pan rails and the use of metric threads throughout the engine. The fuel-injection system for the Vortec 8100 is nearly identical to that used on Gen III engines, right down to the fuel and spark tables in the ECU"

[slotard]

Yeah, not sure why this is in LSx, I imagine he put it in the wrong section.

I have no clue what he has to begin with, if he has a core 454 it's easy to stroke it to 496 without the other changes. I'd be surprised if it could take enough bore to do 502/540.

[SierraMtns]

Originally Posted by americanmusc1e

Considering this is in the LSx swap section, I'm guessing he is referring to the late model Vortec 8100 8.1 motor. Which, according to wikipedia:

"Other important differences between the Vortec 8100 and older Big Blocks include a changed firing order (1-8-7-2-6-5-4-3), a new 18-bolt head bolt pattern, longer connecting rods, different symmetrical intake ports, different oil pan rails and the use of metric threads throughout the engine. The fuel-injection system for the Vortec 8100 is nearly identical to that used on Gen III engines, right down to the fuel and spark tables in the ECU"

Originally Posted by slotard

Yeah, not sure why this is in LSx, I imagine he put it in the wrong section.

I have no clue what he has to begin with, if he has a core 454 it's easy to stroke it to 496 without the other changes. I'd be surprised if it could take enough bore to do 502/540.

I have heard some people call the 8.1L chevys LS Big Block