Hey guys,

Restoring my late Grandfathers 76' K20 and I'm at a crossroads with the drivetrain.

Current engine is a 350/TH350/NP203.

I thought about stroking the 350 out to a 383, but that's been done a million times so I've narrowed it down to two options.

1) 496. My sister-in-laws dad has a 454 that needs rebuilt offered it for free; figured I could stroke it out and just do you usual big block build/Edel heads/intake, big carb, etc...

2) 408 Iron LS. If I did this I would just convert it to fuel injection and I think it would be really nice.

What do you guys think? I know the 496 would make more torque/power, but to be honest I could probably get good power out of the 408 for similar $$$ as well as big block parts aren't exactly cheap either. How would you build it? Obviously a high RPM screamer isn't what this would need.

Not really LS1 based, but pretty much all of the LS knowledge on this board posts here.

Edit: Will be mating to a TH400 and NP205. Will be using this really just for truck work and not a DD. The most it would tow is a average sized boat, and my Z28 to the track; with some offroading fun on the side (6" lift, 36-38" tires)

 

I vote for option 1. A FREE 454 means you can spend more money on goodies.

 

True, but I guess the only free part is basically the block... (Still a good start though )

 

If you want to drive it much, do the 408.

 

I'd go with the 408 unless it's strictly a toy and you're not concerned much about driveability and mileage. A 496 would be cool but LS parts are so much cheaper these days.

 

^ I'll go ahead and respectfully disagree with that statement that the LS parts are cheaper. FAST intakes have come down a little in price but are still almost $900 JUST for the intake (NEW... Used are ~$700). Then add in lines, rails, injectors, FPR, TB, bigger MAF, gaskets, new ducting and a tune and it will run around $2450 just for an intake swap. Heads? Starting at about a grand for decent ones. Stockers? = ~$600.

STOCK parts are a lot cheaper, yes! But the go-fast goodies are rather pricey for parts, depending what you want to do. -Compared to the older parts.

Do you have a tuner within a reasonable range? The carb engine will be easier to "tune."

 

You can bypass the cost of a FAST with a singleplane and 90* elbow, or just go LS3 intake and L99 heads.
From what I've been seeing, a good carb to feed a 496 is comperable in price to a FAST.

 

I think you need to price out a BBC top end that's comparable to what's available for the LSx before you make anymore statements. We're not talking SBC here...

 

^ There are different ways you could have worded that instead of being condescending. Last time I checked, this is a message board which is open to discussion from more than two people. If you want to have a private discussion, take it to a PM.

But you're right...............I don't know BBC part prices. but I WAS referring to the 408 he was planning on building. 408 LS isn't a BB last time I checked. it's still the SBC platform. As far as the 454/496, I was under the impression this was an older block. If it's NOT, then you could just say so and leave it at that.
To me LS means Gen III and IV. Unless I misread. I knew I should have stayed out of this thread.


And just for example.. I'm not sure what GEN the 454 is coming out of, so I just picked one.
Intake for the 454
http://www.summitracing.com/parts/EDL-7561/

Intake for the 408
http://www.summitracing.com/parts/FST-146102/

 

big blocks are very expesive to build and when done are gas hogs that love the **** out of gas, the LS will be your best bet, better performance, fuel economy and maintainance

 

Yes, technically you could get big-block parts cheaper- but I think comparing a dual plane edelbrock vs. a fast intake is rather contrary to the purpose, here. A low budget big-block build would make less power than the LS 408, which IMO would defeat the purpose of having a big block in the first place.

Basically, you'd have a marginally cheaper build that is slower, guzzles more gas, and is temperamental in cold weather.

Granted I've got nothing against big blocks, but with LS cylinder heads practically overflowing out of dumpsters these days (even the rectangle ports), there's no reason an LS build should be expensive (assuming you stay the heck away from all FAST products).

A lot of the popular rodding mags have come to the conclusion that the LS series has replaced the SBC as the budget build platform of choice. IMO either one you decide on, you should do it right, and that makes the LS the cheaper option.

 

Hey guys, thanks for the info.

I've decided to go with the 408 option. And no worries about the FAST, this is a truck motor and the fast is not worth it in the operating range this vehicle will see. Although I may buy a FAST 102 and put it on my Z28, and put the LS6 intake on the 408... I'll probably go with some AI ported 243 heads or spring for a set of AFR heads. Maybe even as cast Trick Flows. I have some time though, I've got to put new cab corners, floor, and front/rear fenders on this thing so that will take me all winter as I don't have a lot of time to work on it right now.

I'll update when I get into the drivetrain, I haven't ran across many LSx powered older trucks. I may even put a 4L80 in her.

 

Sounds like a plan. If you're going for low end torque you shouldn't need to spend a lot on high flowing heads like you would when going for lots of high rpm HP. And if you had the hook up maybe even a 6L80e. 6 gears would be very cool.