SM465 Dilemma

[FUBAR_'78]

Hey Guys,

I'm looking for some advice on whether to keep/upgrade my SM465 or move on. I currently have a 78 K10 4X4. Dana 60 up front, 14 bolt ff in the rear. Running a carved 350, NP 205 T-case and Sm465. I picked up a Gen 6 454 block from a buddies salvage yard and once I my machinist confirms its good I'm gonna start a 496 stroker build. Hopefully when its all said and done it'll have around 500-600 HP and maybe a shot of NOS. The truck is primarily used for mud bogs and what i really need is tire speed off the launch which the Sm465 isn't delivering. The axles have 4.10 gears and the clutch is pretty warn so this are probably contributing factors. Im wondering, with a fresh 496 and clutch, would the Sm465 get the tires moving like the big dogs or is the Sm465 going to rob power? Are there any gearing selections for the trans that would improve this? Or should I start hunting for a NV4500? Thanks guys!

[nonstop]

The 4500 would be better if you are looking for an overdrive, which correct me if I'm wrong, you won't want in mud bogs anyway. Otherwise, the 465 will take what you can throw at it and then some! Gearing options are none unless you go for some of the expensive aftermarket stuff. If you're looking for a 4 speed with gearing options, check out the NP435, as Ford used different options. Finding a GM case will be a bit harder though. Beyond that, you might want to start checking some of the MD transmissions.

[13jraven]

What size tires you running? Rear locker?

I have had NV4500s behind two different 500+ HP trucks. One was in a 74 bronco I sold with a 408 stroker and my present K30 with L92. I really like the NV4500 and had great luck with them but I drive my trucks on the highway.

If the truck is just used for mud bogs, why bother with an overdrive? I rather spend the money matching that BBC and tires with the right gears. Plus the first gear on the SM465 is lower. And I cant remember anyone ever breaking one.

And unless you are planning on a running an AA bellhousing set up for your present manual clutch with z-bar, you are going to need hydro pedals from an 85-87. That is another cost to factor in.

I would put that 496, SM465 with 5.13 gears and a rear locker in your 14 bolt and call it good.

But what the **** do I know, I live in CA where it hasn't rained in years.

[bmchevy1979]

I would just go through the current sm465 and put all new bearings and seals the big block will give you the torque down low where you need it the 350 in my truck doesn't build enough steam until it gets to about 1500rpm and pulls hard to 6500 but the trans will only let me shift around 5500rpm so it pulls my truck down to low to grab another gear in mud but the big block has the curve to match the trans gear spread. If your gears aren't totally shot and your running 33's or 35's I would see how the big block changes things for you. You will likely be surprised by how far the extra torque helps

[wildwilly4x4]

500hp and a clutch dump launch is probably gonna kill your 10 spline 205 coupler, tranny output....and possibly the tcase adapter unless you've already braced it up. the 465 itself can handle that power with ease, as can the 205, but that little 10 spline coupler and thin cast iron adapter are the weak spot. ORD carries a short 32 spline output for the 465, but im not sure if it allows you to run the early 32 spline 205, or just a 32 spline 203.

The 4500 is just as strong as the 465, ratios are close enough to the same, plus you get OD...only bad part is you'll have to go custom to run your current 205 (unless your already running a 32 spline 205), or get an '85 and newer round pattern 205 and bolt it up to the 4500..( takes a little parts swapping, but can be made to bolt on with a few mods at home).

For mud racing id hunt down a th400/205 combo and run a loose converter, or find a factory 32 spline 465/205 setup from an '85 and later rig.

[Jimbo*]

As Wildwilly4x4 stated, find a later model 32 spline 465 with a round 305 input and the correct adapter and crossmember
The adapter is "shorter", and therefore cuts down on twisting leverage due to torque, and lessens breakage
There is also a rare, but not unobtainium, aluminum shift cover from the 1988-1992 round body models that shortens the shifter throw substantially--it would make quite a difference in a mud truck, even though it relocates your shifter 3 5/8" rearward.
Info on the top cover differences can be found here:
http://coloradok5.com/forums/showthread.php?t=203741