Best 454 all around build

[etedeschi72]

I've got an '85 Chevy K20 4x4. Its got a 454 engine connected to an SM465 transmission. I'm toying with the idea of replacing the SM465 with an NV4500 transmission at some point and replacing the 4:10 differential gears with maybe 3:73 gears. I don't go off roading and just use the truck on the road and for occasionally towing a trailer. Can anyone advise me on what a good all around setup or build where I get both good over the road and towing performance? Intake manifold, carburetor and whatever else etc. Oh, it's riding on 33x12.50x16.5 tires if that info helps. Thanks

 

[nvrenuf]

Your going to get all kinds of suggestions but here’s my .02


I’d keep the 4.10’s if you intend to ever tow with the 33’s - especially if you were to go to an overdrive trans.

For a carb in a non hot rod street truck, I highly recommend a quadrajet. There’s no need for a Holley and a well tuned qjet will yield better mpg’s than just about anything other that EFI.

A basic Edelbrock dual plane intake will work great.

The rest depends on how deep you want to get and spend. An Edelbrock Performer cam kit is pretty tame but a decent step up from stock. If you’re doing a complete overhaul and buying pistons I’d get something to step up the compression just a bit, the factory combo is about 7.9:1 compression so getting it up around 9:1 (not necessarily over) will make a good difference in power.

The original 80’s “peanut port” heads will be fine for you but if you get bit by the performance bug just know that while they work they don’t breathe well above 4k rpm.

 

[Shorty81]

My .02, keep the 465 and your 410 gear. My 454 was stroked and bored to a 496 with 781 iron heads. Truck makes gobs of low rpm power. Enjoy your truck for what it is, if you want fast or creature comforts buy a modern truck. The faster you drive the faster life passes you by... 496, 465, 208, 31" tires. 2 grand at 55, happy truck

 

[Catbox]

If it were mine and this is what I am going to be doing once other things are done in the project pile....
I would pull a L-29 7.4L Gen 6 Vortec big block out of a junkyard vehicle and build off of that.
Here my kid and his buddies pulled a Gen 6 and its matching 4l80 transmission from a junkyard Suburban.

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The L-29 has far better heads than the peanut ports.
They have a larger intake runner at 235cc (200cc PP) and the combustion chamber is modern shaped and small chamber around 100cc (119cc PP).
That makes for better flow and 9:1 compression ratio off the bat.

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What is also great about this engine over the Gen 4 is that it is a roller cam engine.
By putting a decent intake, headers, and a carb the internet tells me you will get around 375hp and 450ft/lbs.
This is the intake on my Gen 4 big block and it could be used on the Gen 6, but I also have a RPM version that I will probably use on the Gen 6.

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Here is the RPM with the carb that is on the truck currently as well.

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The headers and exhaust that are in the truck already will bolt right up and make all the good noises as well.
More power all around without cracking the engine open sounds like a win to me.
It gets even better if you want to change the cam out and find more power.

 

[Catbox]

If you just want to find a set of heads to swap onto your existing engine, the L-29's can bolt right on as well.
That will give your Gen 4 engine a nice full point of compression and it will make you more power all around with just those.
The internet states it is around 30 to 40 more horsepower.

I was originally going this way with the current big block in my truck to make it that much snappier, so I picked up a set of the heads.
To install the Gen 6 heads you just need the right set of gaskets to place them atop of your Gen 4.
These are what I was told to use, I just have not as I now have the complete engine instead of just the heads.

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This is the casting number you want from the L-29 and the years for the Gen 6 are 1996 to 2001.

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Another pic of the modern chamber...

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I also plan to upgrade my engine to a guided set of rocker arms with half a set of 1.7 and half a set of 1.8 rocker arms.
This is a set of just 1.7's I found in the swap meet a few years ago for $100...

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The pool is deep, make sure you do your homework and know what you are doing before you spend a buttload on stuff and it is all wrong.

DO NOT BUY GEN 5 HEADS OR ENGINES AS THEY ARE NOT THE SAME AS THE GEN 6.
THEY ARE POOP IN MY EYES.

 

[SquareRoot]

8.1, Sniper, Powerglide and 3:08. Covers all the bases.

 

[ma3600vz]

I would keep the the gears that you have now keep the sm465 for now if you want 5 speed I would get a early nv4500 I would also start with a junk yard l29 how a 8.1 swap would be pretty cool or a tall deck swap if you can find one and you really want to spend some money I think that a ht502 would be great I would run a quadrajet

 

[bucket]

So, an '85 K20 was not available with a 454 from the factory. Before deciding the best course of action for the needs, you need to determine what your engine actually is. It could be whatever someone stuck in it. Block and head casting numbers would be very useful.

 

[desertdog1]

I have a 83 C20 454 with SM 465 granny 4 speed and 4:10 rear axle. I also looked into replacing the granny with a NV4500, but I don't drive the truck very often so the large $$$ investment was not worth the hassle. It is not easy to find a used NV4500 where I live and you will need a lot of mods and special adapters to make it work. When I bought my truck 22 years ago it had a GearVendor over/under drive installed and my mpg was 11 city/13 highway when I engaged the GV. The GV has since stopped working so I am down to 9/11 mpg. I might get a rebuilt GV (about $1200+ the last time I checked.) I think the best mpg improvement would be a more open rear axle ratio (3:23, 3:73, etc.) but you would lose a lot of low end towing power. My 454 is a GM Goodwrench reman replacement engine (bored .030 over) but I think it is still only stock 230 horsepower. The 454 truck engines are not designed for high end horsepower but do produce a lot of low end torque, which is good for towing, but that 4:10 really makes the engine scream at highway speeds. A working Gear Vendor makes highway driving a lot easier.

 

[Craig Nedrow]

Nice setup to begin with the 4L 80 E has a .76 I believe overdrive calculate your tire size rear end gear in overdrive for over the highway RPM and set up your motor to work in that range. I have a small RV cam ebrock air gap intake manifold 750 Holly flow tech 1 7/8 headers. You don’t need to power brake to burn off the tires.

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[JD Miller]

Sm Blk chevy or Cummins diesel