Engine swap for street and towing

[Big Ray]

Save yourself a lot of time and money and find a 400sbc and rebuild it. Flat top pistons if you want, rv cam, quadrajet, long tube hedders, stock heads and make sure you use a big block rad. Gear it around 330 to 370 . You will be amazed at the torque these engines make. No need to change connecting rods.It won't make much power above 4,000 rpm but will be outstanding up until then. I've had a couple of these combos and still have one in my '72 k5. you won't get tired of the torque!

Got one in my K5. Love it.

 

[Craig Nedrow]

I have had two 350's and a 454.

Don’t bother with the 6L90. It’s hard to beat a 4L80 for comfort, durability, and ease of use. Gear the differential so at 65-70 mph the engine is starting to come onto its torque curve

Go with the big block. And since torque is the name of the game here, don’t limit yourself to big block Chevy. A 455 Buick or olds swap, or even a 500 Cadillac is a fairly easy project. Before I had my diesel Ram, I used my dads 455 olds swapped 81 GMC to haul my car to the various races. It’s a basically stock 71 455, the truck has 3.08 gears and the trailer loaded weighs around 6500-7k. It has zero problem pulling the trailer and interstate speeds.

Diesels are hard to beat, but with the cost of diesel fuel the added fuel economy isn’t nearly the advantage it use to be.

All Q-Jets are capable of at least 750 cfm. The small block carb will need some calibration changes for the bigger engine. Get with a Q-Jet specialist, they can provide the expertise and parts to get the carb right.

Matt is right I believe. I have had two 350's and now a 454. Here is the swap, super easy: https://www.gmsquarebody.com/threads/1973-k20-350-to-454-swap.29840/

I am a retired machinist that went back to work in a speed shop machining engines. The olds have big everything inside, and I love my 454. Runs great on 87 octane with 36 degrees of advance, tuned with an AEM A/F gauge and Bosch injectors. Snappy, great in the hills getting wood, smokes em' at will. I am also a farmer rancher and tow hundreds of tons of hay, the 454 is the best of the three motors I have had in it. This winter I am swapping a 4l80e which will reduce engine RPM by about 1/3. I now have a Engine Pro "RV" cam in it, but will switch to a COMP Cams Xtreme Energy 4x4 Cam and Lifter Kits K11-239-3, from Summit. Just got done machining a stroker 383. Also building a 400 sbc, always liked them. What you don't see is the thick walls and massive bottom end of the BB engines. Also the LS style motor, the cast iron blocks are much heaver then the 350. Have one up on the boring machine that I will work on tomorrow. Conclusion: Big block.....My K20

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[jaredpears]

So I think I’ve pretty much settled on a vortec 454 converted to carb and hei for the motor, and then I think I’ll be going with an nv4500 since they also came behind those motors if I can find one locally, my suburban is a k10 so it’s got a 700r4 in it right now and I know I that won’t last behind the big block. And it’d be nice to keep it non electronic. My local junkyard has engines priced out at 250$ pull it yourself. so I’ll see what I can get there and then just replace gaskets and maintenance parts before I throw it in. And then no more v-belts either!

 

[Bennyt]

So I think I’ve pretty much settled on a vortec 454 converted to carb and hei for the motor, and then I think I’ll be going with an nv4500 since they also came behind those motors if I can find one locally, my suburban is a k10 so it’s got a 700r4 in it right now and I know I that won’t last behind the big block. And it’d be nice to keep it non electronic. My local junkyard has engines priced out at 250$ pull it yourself. so I’ll see what I can get there and then just replace gaskets and maintenance parts before I throw it in. And then no more v-belts either!

Definitely would do a professionally built Quadrajet to maximize power and MPG.
V-Belts were on some of the 454's into the 90's so it might be hard to find a factory serpentine set-up.


As an alternative to a 454...I'd also look into a CAD 472/500. It would cost a few dollars to set it up correctly, but you get Diesel Torque, plenty of power, can run a higher gear for MPG, quieter/ smoother than probably any other V8, fairly compact package which I know isn't much of a concern, and weight is 100-150 pounds less than a BB when equipped with aluminum heads/ intake.

 

[Craig Nedrow]

So I think I’ve pretty much settled on a vortec 454 converted to carb and hei for the motor, and then I think I’ll be going with an nv4500 since they also came behind those motors if I can find one locally, my suburban is a k10 so it’s got a 700r4 in it right now and I know I that won’t last behind the big block. And it’d be nice to keep it non electronic. My local junkyard has engines priced out at 250$ pull it yourself. so I’ll see what I can get there and then just replace gaskets and maintenance parts before I throw it in. And then no more v-belts either!

The vortec is a roller motor, makes more HP then the marklV, and is the preferred motor. Richard Holdner has done many mods to them and is a welth of info. You will need a good 750 holly style carb, or bigger if you mod it much. there are carb formulas at Summit. I really like the E-bock air gap on my 454. Man you are gonna love that new motor .....if you can find one.