Do I rebuild my SBC or swap for an LS3?

[Vbb199]

I have to say, if i was an entry level mechanic and knew nothing, these "simple swaps" that are 5 paragraphs long explaining how simple they are would be far more intimidating than just the 1 paragraph posts that read "put another 350 in"

 

[DoubleDingo]

I have to say, if i was an entry level mechanic and knew nothing, these "simple swaps" that are 5 paragraphs long explaining how simple they are would be far more intimidating than just the 1 paragraph posts that read "put another 350 in"

Yep, a replacement 350 is a two-day job at the worst and you're back on the road, or farm/ranch working the truck like it is being used now. An LS is overkill for this application. BUT, those that have done the swap will disagree and push for the swap instead of a simple replacement.

 

[andybflo]

When taking the entire computer/harness from a donor, do you just cut the wires off at the firewall or are there other components inside the donor besides a dbw pedal?

You take the two connectors off the PCM (they're color coded) and chase those wires out. If you have a separate pedal box/DBW pedal, there's a short harness there (follow the pedal plug to the firewall, to the small box.)

The dash harness is separate. Leave it alone. You don't need it. Your square's dash/lights/accessories/etc are left alone.

Most harness builders will give you a battery, a ground, a switched ignition, and a small fuse/relay box as a second, essentially standalone harness.

Legitimately, if you need direction, part numbers, tuners, or who I used to clean up the harness, PM me. I'll toss some help your way.

 

[andybflo]

Yep, a replacement 350 is a two-day job at the worst and you're back on the road, or farm/ranch working the truck like it is being used now. An LS is overkill for this application. BUT, those that have done the swap will disagree and push for the swap instead of a simple replacement.

It's why I told him to define his mission.

I run far older tech on the road regularly than a Gen1 SBC. If it's something he wants to be a daily, though, they're a bad choice.

I've left plenty of my rides with factory motors that are far older than me. But they're weekend warriors (other than my Caddy, I drive that everywhere and it's pushing 80y old) and get towed by the LS powered squarebody.

 

[Frankenchevy]

You take the two connectors off the PCM (they're color coded) and chase those wires out. If you have a separate pedal box/DBW pedal, there's a short harness there (follow the pedal plug to the firewall, to the small box.)

The dash harness is separate. Leave it alone. You don't need it. Your square's dash/lights/accessories/etc are left alone.

Most harness builders will give you a battery, a ground, a switched ignition, and a small fuse/relay box as a second, essentially standalone harness.

Legitimately, if you need direction, part numbers, tuners, or who I used to clean up the harness, PM me. I'll toss some help your way.

I have to get to that point first. I have trouble trusting people on CL with a motor out of a “low mile” this or that. I want to see and hear it run. That problem was further compounded by crazy used truck prices. Everyone thinks a running 2001 Chevy truck is worth $10k now. I have a project I’d like to LS swap, but I need to find a totaled vehicle close to the 100,000 mile mark or preferably less.

 

[OneShot]

Good choice sir, just what I'd do.

I'd be interested in the intake.
Does it have the middle bolts at a different angle for TBI heads?

I will check when I get home. I'm on business travel at the moment. I'll get you the casting / model number too. I found an Edelbrock 2101 Performer intake on Facebook for $100 near me (neat!) that I think I'll go with.

Having a bit of trouble finding some 462 or 291 heads near me though.

Also, any recommendations on a good truck cam? I don't mind a bit of a lope at low RPM, just in case you were wondering

 

[Craig Nedrow]

I love these threads...I have had two 350 in my truck, and now I have a 454, my first big block. One 350 was stock with an AFB, ran will till it died. Second SB was a circle track motor I built years ago and was setting in the shop. Big cam sounded so sweet, except at the gas pump. It also had low vacuum. Found a motorhome 454 that had been rebuilt, nothing fancy, cylinders honed, rering, small rv type cam, Edelbrock air gap, heads rebuilt. Holly 750 vacuum secondary electric choke 4160 converted to a 4150 style secondary block. I tuned it with a AEM fuel meter and a Bosch wide band welded into my collector pipe. Had to change the squirter, jets on both ends, runs down the road @ 14.2 af, when I stomp on it (I do that alot) af is right around 12.4. Truck runs like it has fuel injection, starts up in the Washington Cascade mountains where I live in winter. I used this truck as a farm truck mostly trailering the hay I grew to customers. All this to say love that 454. At the moment I am working in an automotive machine shop building motors. Oh yeah while I farmed, I also did machine work 40 yrs worth. The SB is a great motor, can make 1hp per CI easy and relatively cheapy. Just for fun, the 454:

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. Also have LS1, and an LQ4 for swaps, maybe another time.

 

[mrdap]

My personal opinion.
If it's your work truck it's your second vehicle it's not your daily driver, it's not a road queen it's not a show Queen.
I just rebuild the existing engine as is and put some good valve seals rings etc in it.
LS swap is going to cost more money for sure, and for this kind of vehicle it's just not needed or justified. If you have access to better heads well it's all apart and they're either free or inexpensive than sure, by all means install the better heads or other parts while you have it all apart.
Just my two cents.

 

[Ricko1966]

By the time you buy and do everything necessary for an ls swap,you will have spent more money and time to have a used motor than you would to have a fresh 350. As the Vortec heads and no heat manifold my experience hasn't been in super cold, its just above freezing with moisture in the air the carb ices up until it is so air restricted it won't run. Much colder no problem a little warmer no problem. That's Kansas,now just for fun I was reading IDK car craft or something,I saved it somewhere I'll find it of the of the magazines took a small block with a cam dynoed it swapped on Vortec heads gained 30 hp,swapped on heads from summit,swapped on brodex and maybe it was AFRs but all the after market heads stomped on the Vortecs,didn't need a special manifold and weren't that pricey. I wouldn't spend the money for 30 hp.How about that ,it wasn't even 30 anyways here it is.

Eight Budget Small Block Chevy Heads Tested

We compare and contrast eight budget small block Chevy heads.

www-motortrend-com.cdn.ampproject.org

 

[Rusty Nail]

Holley >Edelbroke

Sbc > Ls

Getcha some (sbc) TPI #083 (Z-28 ,Trans Am) heads and build the snot out of them. You'll be way ahead.


Yep 083.

 

[Ricko1966]

I will check when I get home. I'm on business travel at the moment. I'll get you the casting / model number too. I found an Edelbrock 2101 Performer intake on Facebook for $100 near me (neat!) that I think I'll go with.

Having a bit of trouble finding some 462 or 291 heads near me though.

Also, any recommendations on a good truck cam? I don't mind a bit of a lope at low RPM, just in case you were wondering

Okay finding 292s good luck over the counter chevy hp heads,but they weren't put on cars from the factory so good luck finding some. 462s no bolt holes so aftermarket brackets, 50 year old design they'll need guides and valve seats minnimum and still won't run as good as modern heads. If you have to go old school double hump you want 041s or 186s yea 041s aren't technically double humps,but same heads different markings. Buy newer heads even just some 601s I think Rusty meant 083 heads which would be real good and wouldn't need seats installed

 

[Ricko1966]

I've changed my mind,J2 in the bed.

 

[mrdap]

Some good information being posted here

 

[Ricko1966]

Duplicate,sorry

 

[SquareRoot]

Some good information being posted here

Ya thunk?