Rod thrown, what now?

[Eargesplitten]

I threw a rod in my 180k mile ‘92 K1500 with a L05 a couple days ago and am trying to decide how to approach this. I’ve decided that no matter what I do this truck is never going to be a heavy duty long haul power machine so I’m not inclined to spend LS swap money on it.

From what I read a 454 will bolt straight in (manual transmission) albeit I should probably replace engine mounts and will need to beef up the front suspension to handle the extra weight. I found one known good fully dressed plus headers with 130k miles on it for $1k. I need to see if it includes the wiring harness and ECU. If it doesn’t have the ECU but does have the harness, do I need a whole new ECU or just a chip? Any feedback on this with the understanding that I’m just trying to get it up and running with a bit more low end grunt, not making a fast truck? Does the 454 need a bigger radiator? I’m thinking about going electric fans.

An l31 or another L05 are also options but big numbers tickle my lizard brain and with the gearing on this thing it wants to stay from 1-2k RPM anyway which suits the big block. An L31 or L05 also seem to be more expensive than this 454 from what I’ve seen.

 

[packer0440]

Big block and small block have the same bellhousing and engine mounts so it will go in. You will need at least a new chip, possibly ecm not sure. The fuel pump is also a higher pressure pump so that will need swapped. I assume you are keeping it stock so I would make sure you get the wiring harness since some of the sensors have different pigtails. Since your truck is only a 1500, you will need to upgrade the radiator to the bigger one. I assume you will be getting the accessories with the 454 which is good because many of them will not swap. Might need to reuse the pump off of the 350 if the engine comes with a hydroboost pump, and get AC compressor lines for a 454. Check out what headers come with the engine, as putting headers in a 4x4 (especially a big block) is a pretty tight fit.

IF you can get the right fan and shroud for a 454 I would stick with the clutch fan. Keeps everything plenty cool. Stock 454 trucks also have an auxiliary fan in front of the condenser, although it is designed only to run when temps get pretty hot so you could wire it differently if you like. Make sure you get a flywheel and new clutch if it doesn't already come with.

Assuming you have a light-duty trans, it will probably be OK but don't go nuts with it as they didn't really come behind 454s. 454s also came from the factory with a full float axle, much stronger than a 10 bolt if that's what you have. You would probably be ok with it, but again, don't go nuts with it. A 14 bolt semi-float would probably be sufficient if you ever decide to upgrade (or you happen to have it already).

The TBI 454 is a great motor for low-end torque and has considerable pulling advantage over a 350. With your gearing, I think it would be a good choice. Just thought I would lay out things that would probably need to be changed. Just remember, it seems like a lot, but an LS swap would probably involve just as much work. Putting a good 350 would be the absolute simplest solution.

 

[1998_K1500_Sub]

@packer0440, nice summary.

I wonder how the 454 would perform with the stock L05 radiator. He stated it's "never going to be a heavy duty long haul power machine". It's a curiosity.

Somebody in a recent thread said the AC lines for the 454 engines can be hard to find / purchase. OP, if it matters take note, assume it's the truth until you prove otherwise.

As @packer0440 noted, at least in 1998, the 454 got the NV4500 RPO MW3 transmission.

The NV3500 RPO MG5 (close ratio, C truck) and RPO M50 (wide ratio, K truck) showed up behind the small blocks, although the NV4500 MW3 was provided on some.

I might assume the clutch was different accordingly to match the engine torque and the input shaft of the transmission.

See the attached, from the 1998 FSM.

 

[packer0440]

@packer0440, nice summary.

I wonder how the 454 would perform with the stock L05 radiator. He stated it's "never going to be a heavy duty long haul power machine". It's a curiosity.

Somebody in a recent thread said the AC lines for the 454 engines can be hard to come buy. OP, if it matters take note, assume it's the truth until you prove otherwise.

As @packer0440 noted, at least in 1998, the 454 got the NV4500 RPO MW3 transmission.

The NV3500 RPO MG5 (close ratio, C truck) and RPO M50 (wide ratio, K truck) showed up behind the small blocks, although the NV4500 MW3 was provided on some.

I might assume the clutch was different accordingly to match the engine torque and the input shaft of the transmission.

See the attached, from the 1998 FSM.

I think I was the one who said about the lines, from personal experience. NAPA was the only place I could find that had some for a 454, and they had to order them from super far away. The 350/V6 lines are oriented sideways and will stick up straight in the air on big blocks (at least for the original R12 AC systems.). Later ones might be interchangeable.

 

[packer0440]

Also if the 454 happens to be from before 1991, you WILL for sure need a new flywheel, because those are externally balanced and have a counterweight on the flywheel and balancer.

 

[evilunclegrimace]

Rock auto has a listing for the A/C hoses for a '92 454.

 

[454cid]

I think swapping a big block into a 1/2 ton is a bad idea as a cheap way for a bit more power.....too many things need to be swapped. I would not use the original transmission from the 1/2 ton, or the 10 bolt tear axle.

 

[packer0440]

Rock auto has a listing for the A/C hoses for a '92 454.

That was the year I had to get as well. I think they were out of stock at the time I was looking around.

 

[Schurkey]

I’m not inclined to spend LS swap money on it.

Saves a lot of hassle, too.

I should probably replace engine mounts

Good luck with that, at least in a 4WD.

will need to beef up the front suspension to handle the extra weight.

Yes.

Does the 454 need a bigger radiator?

Yes.

I’m thinking about going electric fans.

No. It takes "real" (expensive) electric fans to cool a V-8. Even more to cool a big-block.

An l31 or another L05 are also options but big numbers tickle my lizard brain and with the gearing on this thing it wants to stay from 1-2k RPM anyway which suits the big block. An L31 or L05 also seem to be more expensive than this 454 from what I’ve seen.

Depends on what you can find for a "used but usable" 5.7L.
But you'll never get 7.4L torque from a 5.7L without spending money on supercharging, nitrous, aluminum heads, and/or extensive internal engine mods.

The fuel pump is also a higher pressure pump so that will need swapped.

7.4L TBI got higher-pressure pump in the later years, but not the early years.

A higher-pressure pump isn't going to hurt anything, provided the fuel return plumbing can handle the pump volume. Not an issue with OEM pumps, but can be trouble with high-volume aftermarket pumps.

you will need to upgrade the radiator to the bigger one.

Very likely. Strongly recommended.

I assume you will be getting the accessories with the 454 which is good because many of them will not swap.

Yup. Not so much the accessories themselves, but the brackets that hold the accessories.

Check out what headers come with the engine, as putting headers in a 4x4 (especially a big block) is a pretty tight fit.

Yup.

IF you can get the right fan and shroud for a 454 I would stick with the clutch fan.

YES.

Make sure you get a flywheel and new clutch if it doesn't already come with.

The small-block flywheel from a 1-piece-seal crankshaft will not bolt to a big-block crankshaft.

Also if the 454 happens to be from before 1991, you WILL for sure need a new flywheel, because those are externally balanced and have a counterweight on the flywheel and balancer.

ALL stock 454s are externally balanced with weights on the flywheel / flexplate and damper. Issue is, they don't all have the SAME amount of offset weight.

For example, with the 1-piece-seal 7.4L cranks, you have to know if it's a forged-steel crank or a cast-iron crank, 'cause the offset balance weight on the flywheel/flexplate is different. And I'm not sure that either one of those offset weights on the flywheel/flexplate is the same as what's needed with the 2-piece rear main cranks.

 

[packer0440]

Saves a lot of hassle, too.


Good luck with that, at least in a 4WD.


Yes.


Yes.


No. It takes "real" (expensive) electric fans to cool a V-8. Even more to cool a big-block.


Depends on what you can find for a "used but usable" 5.7L.
But you'll never get 7.4L torque from a 5.7L without spending money on supercharging, nitrous, aluminum heads, and/or extensive internal engine mods.


7.4L TBI got higher-pressure pump in the later years, but not the early years.

A higher-pressure pump isn't going to hurt anything, provided the fuel return plumbing can handle the pump volume. Not an issue with OEM pumps, but can be trouble with high-volume aftermarket pumps.


Very likely. Strongly recommended.


Yup. Not so much the accessories themselves, but the brackets that hold the accessories.


Yup.


YES.


The small-block flywheel from a 1-piece-seal crankshaft will not bolt to a big-block crankshaft.


ALL stock 454s are externally balanced with weights on the flywheel / flexplate and damper. Issue is, they don't all have the SAME amount of offset weight.

For example, with the 1-piece-seal 7.4L cranks, you have to know if it's a forged-steel crank or a cast-iron crank, 'cause the offset balance weight on the flywheel/flexplate is different. And I'm not sure that either one of those offset weights on the flywheel/flexplate is the same as what's needed with the 2-piece rear main cranks.

Interesting info about the balancing of the engine. I had read that small blocks became internally balanced when they went to a 1-piece seal, figured that applied to big blocks. Def makes it harder to figure out what you need!