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So I've been driving my truck with the 401 for a while now and it's not really living up to expectations. I do need to do some tweaking and so forth. But I discovered a problem. My newly rebuilt 401 is burning oil. At a non-trivial rate.

I've not been happy with a few of the compromises I've had to make with the 401 and 700R4 conversion and with the oil consumption, excessive heat, and a few other things, my long term plan is now to drive it until I can do another swap.

I know everyone says just do an LS swap. And I've thought about it. But this is Truck Norris. I'm thinking bigger. I really don't want to go diesel because I just don't feel like it. What I'm settling on is going big block Chevy. I've been reading up on what limited information is out there and I'm aware of the fact that there will be some tweaking to make it fit. I already have a hydroboost system ready to go in anyway and I can deal with the other things.

The truck already has J20 axles so I know they'll handle a mild 454 with no problem, including the weight.

I will need to pass emissions and my plan is going with factory or factory-like equipment from the donor. As long as it's 1986 or newer, it will work in my truck.

Thing is, I can go a couple different routes:

1. Go full custom with a reman block, aftermarket fuel injection, and build up a 700R4 to handle it. But the emissions passing is questionable.
2. Grab a TBI 454 out of an existing older truck and do a built 700R4 (because I want overdrive with the axle gears I already have so a TH400 isn't really an option.)
3. Grab a Generation V (1991-1995) with the 4L80E and t-case. Take everything I need from a donor truck and sell the carcass.
4. Grab a Generation VI (1996-1999) similar to the Gen V.
5. Grab a Generation VII (2000-2006) 8.1 with the Alison trans and t-case. Again, taking everything and keeping most of it.

I'm really not inclined to use the 8.1. Sure, it's bigger but there just isn't much aftermarket for it and that makes the work harder. Besides, with the taller deck, fitting it is that much harder.

Full custom with aftermarket injection may make it harder to get through emissions so that's lower on the priority scale.

A TBI 454 would work but it's down on power compared to newer versions.

My preference would then be either the Gen V or Gen VI. I can get pretty much everything I need from a donor truck and swap it in as a unit. There is enough of an aftermarket that dyno tuning it would be possible.

Like I mentioned above, I'm pretty well sold on aluminum heads no matter what, just to get weight down. And I'm not looking at trying to get 1,000 HP out of it. I just want a mild build that will give me decent reliable power running on pump gas.

So those here who know about the big blocks, what advice can you offer? Anything to look out for from a given generation of the engine? Any real benefits to one over the other?

Chevy TBI doesn't like to play with mods as it is a MAP system vs a MAF system. The aluminum heads could give you a bit of trouble there. You're also a bit limited with the power it can make even with tuning/mods. I would say option 1 or something different.

IMHO all you're really gaining with a big block vs an LS swap is low end torque, which for these trucks is important, but there are a bevy of other badass engines you could put in it to do that. In terms of reliability/mileage/part availability its hard to beat one of the LS swaps and you could do a 6.2L or the LSX 454 and I bet you'd be better off than swapping in an older carb'd version. Just my two cents.

I ran a 454 in one of my trucks for a while. The engines fit but generated a lot of heat in the engine compartment when idling. They do have lots of torque and with 35's it worked good.

I'm a big fan of the Gen VI engines. Full roller, MPFI.

I think an LS would be a better engine choice. Unless you are putting some mods to actually wake up the big block they are kind of dogs for their displacement.

HeavyMetalThunder_81 wrote:I'm a big fan of the Gen VI engines. Full roller, MPFI.

That's the direction I am thinking. But how hard is it to upgrade to full roller on a gen V since I'm doing a cam swap anyway?

Another one bites the dust.
440 Mopar comes to mind but that's just me.

I tried. I really did.

The Mopar sounds interesting but I have emissions to deal with so it needs to come from an 86 or newer truck. And chevy is just so much easier to find.

The good news is that I won't start the swap until after Ouray so the truck will be there with an AMC at least once.

8.1L's are known to have oil consumtion issues as well. Still, that's the route I would go if I where going to swap in a modern motor.

Loads of power and torque. More than a 6.0l. The base 8.1l puts out 30 more HP and about 90ft lbs more torque at a slightly lower RPM than the 6.0l.

Kaiserman wrote:8.1L's are known to have oil consumtion issues as well. Still, that's the route I would go if I where going to swap in a modern motor.

Loads of power and torque. More than a 6.0l. The base 8.1l puts out 30 more HP and about 90ft lbs more torque at a slightly lower RPM than the 6.0l.

The 6.0 has a ton of mods and tuners available though. The 8.1 really is limited in terms of the after market.

Stuka wrote:

Kaiserman wrote:8.1L's are known to have oil consumtion issues as well. Still, that's the route I would go if I where going to swap in a modern motor.

Loads of power and torque. More than a 6.0l. The base 8.1l puts out 30 more HP and about 90ft lbs more torque at a slightly lower RPM than the 6.0l.

The 6.0 has a ton of mods and tuners available though. The 8.1 really is limited in terms of the after market.

Yup. The aftermarket almost doesn't exist for the 8.1 because a great many parts don't swap over from the earlier gen big blocks. That and the fact that it's physically larger makes it that much harder to fit.

It's not a bad engine per se but as a swap candidate it has a lot of limitations.

6.0/4l80e swap is more than enough.

How about a 500CID Caddy motor with EFI? I will be 100lbs lighter than a BB Chevy...

ClovisMan wrote:6.0/4l80e swap is more than enough.

Maybe for a regular FSJ. But this is Truck Norris we're talking about. There is no fist big enough.

My old 401 (non EGR, performer intake, TBI) passed the IM240 emissions test just fine. If they don't know it's a swapped motor, they may not care about visual. <shrug>

I would think a 454 EFI motor would run cleaner than an aftermarket wet intake TBI'd 401.

There is no replacement for displacement .