I know this question has been asked and answered with varying degrees of success and interest. But I am trapped at home due to quarantine with little to occupy my time so I have decided to finally tackle the issue of my engine swap and hopefully lay this issue to rest. For months now I have been agonizing over which direction to take on a new heart for my 73. When I first opened this can of worms it was with the simple intention of dropping in a reman 383 from ATK. Apparently in the 10+ years since I have looked into this, things have changed!

I have discovered the LS swap. Though it seems that the further down this rabbit hole I venture the more confused and inundated with info I become. It would also seem that the advent of this new option has had an effect on the more traditional options. In the Denver area I have found big blocks to be plentiful and inexpensive. There are also many SBCs for sale near me that are affordable.

My budget is 4k. I would like to have around 400hp. The car is driven a couple days a week. Mostly just street cruising. But I want driving this car to be as much fun as looking at it is.

What is the best way to accomplish this within my budget? My heart says old school SBC. On the other hand I’ve never had a big block and the thundering appeal there is obvious. Especially considering that I’ve seen several near me for under 1k. Obviously the real expense there would be in making the thing perform like I want. Is it even possible with my budget?

I am very intrigued by the LS swap. The drivability, mpg, OD transmission, all appeal to me. Not to mention the hp. The sheer volume of conjecture surrounding this gives me pause though. I have waded hip-deep into the LS threads and there doesn’t seem to be any consensus on the best way to do it.

All this brings me back to the 383. I have seen these in the 4K neighborhood with a warranty. The drop-in, bolt-on nature of this is a huge benefit. The old school look and lopey sound of a properly cammed SBC is how I imagined my dream car. Which this is. I only want to do this once.

So, are either of the 2 options I hadn’t considered (big block, LS) realistic at my budget? Does one provide substantial benefit over the others? I want this thing to rip! I want it to sound good doing it. I do want some measure of reliability. I know the old adage, you can have fast or cheap, but not both. But my budget is what it is. If you’ve made it this far, I would like to thank you! I’m throwing this out there knowing that it will be met with a measure of eye rolling but I am hoping that under the circumstances there may be others who, like me, find themselves with an abundance of free time and wish to opine on this age old topic! Or those that wish to share their experience with these engines. Thanks in advance to any and all who take the time to help me out! I am itching to pull the trigger and get my baby back on the road!

 

LS swap is probably a little bit optimistic for 4k. Especially once you start considering how to tackle fuel, etc. I'd go 383.

 

Can you build a 400 hp big block for $4,000.00?
If you just want a nice cruiser, I would say, yes you can.
The key will be if you can find a good Mk-4 block and can use the crank, rods and heads.
A good set of aluminum heads would make 400 hp an easy goal, but would take a big chunk out of your budget.
Big torque is what you will get out of a big block and choosing the right cam and piston combo will make it a fun drive.

 

383....especially since your goal is 400 Gross HP (should be able to get 425-430 Gross HP easily) with strong mid range torque.

Real world feedback:

My 355 L-82 rebuilt with quality parts in 2014 by me makes about 425+ Gross HP with very strong mid range torque from the moderate roller cam focus. It is a BLAST to drive, even compared to my 10 C6Z06 weighing 3,100 LBS with 505 Net HP. Both are fun....take what you want from that description.

 

Don't forget you might need to spend something on a trans upgrade. I would opt for the stroker and try and keep a little set aside for the UNEXPECTED. A 383 with maybe fuel injection should give you a reasonably cheap yet fun and reliable car. As for the 454 I don't think gas prices will stay this low forever. Just my thoughts. Good luck

 

A well planned 383 stroker with good heads and a matched torque converter, if auto trans, will get you what you are looking for.

 

my choice not on ballot
buy a rebuildable core iron head 5.7L 350 Vortec rpo L31 vin code R as in millions of chev gm lite -mid trucks 96-2002.

has good vortec heads and roller cam ... rebuild it w/ quality parts and bigger cam easy reliable 400/400 for under S3K
another $500 can up that from 355 to 383

imo nuts to pay atk bp etc for motor that can't be rebuilt again because they bored it to limit
your money, time, car

 

I have a big block that I just built, and so many things about it make it way more expensive to build than a small block I spent 2 -3x your budget. And you would have to change items in the car for a BB. too. A 383 will make almost as much TQ as a big block, and waaay more than the stock '73 350. Unless you want/need 500hp, go for the 383. I bet you wind up with 425HP anyway. If you can find a 400 block, then you could could have a 406 SBC and even more TQ.

SBC are one of the most numerous and least expensive V8 engines to rebuild and they can make some serious power. 400Hp is easy with a nice streetable build. .OTOH the maybe $100 extra dollars for the 383 and it's TQ is money well spent.

From what I have read putting an LS into one of these old cars requires a lot of other changes, and time, and money. Only for the truly dedicated.

 

Find a Gen 6 454. 4-bolt mains, priority main oiling, factory roller lifters, 1-pc rear main seal. Factory heads will support your goals with a minor cleanup. You will have to use an electric fuel pump because production blocks aren't set up for mechanical. They still show up from time to time when people part out vehicles, most sell for $500 to a grand. Do a Craiglist search, you should be able to find some in the flat parts of Colorado and Oklahoma from either farm trucks or irrigation wells.

Everybody and their dog are doing LS swaps into everything. Smallblocks are cool, but nothing talks muscle like a big block under the hood.

 

Wow, thanks for all the quick replies! So far the consensus seems to be 383. The vortec rebuild is interesting too, something I hadn’t considered... excellent point made about cores being bored to their limits.

 

LS if you can source it for cheap, and you like electronics. Otherwise, what @jackson posted about the L31, and keep your Q-Jet. At least, that's what I'm considering for my two cars when they need new engines.

 

I have a 71 BB trans crossmember and driveshaft for a turbo 400 for sale that with work in that car. I say BB!

 

I sincerely doubt you can do an LS swap for $4k. The 383 is a nice alternative. Lots of torque and that's what you feel first in the seat of your pants. With a set of headers lots of people will think it's a big block under the hood .

 

Consider installing a SBC 400CI, 460HP/470TQ for $1400 more through Blueprintengines.com

https://blueprintengines.com/product...tor-bp4001ctc1

 

As already mentioned the easy thing to do is build to 383 cu. 400 hp a mild one can do that with plenty of tq. Your barely talking over 1 hp per cu. Inch. Next up 454 old original oval port heads just a pickup engine with a little compression and a mild cam would put you past the 400 hp mark with even more tq. The LS would not even attempt it with 4 grand and a pain in the backside to do. Wanting an LS I say just go buy the whole more modern car and be done with it.

 

When I owned my 69 BB the engine had a spun bearing. I replaced it with another 427 engine. A friend of mine suggested a built 350. I said " I can buy a stock 427 with 390 HP and just drop it in the car.No mods. With today's Fuel Injection systems a BB would be great. All that torque. Man do I miss my BB

 

I too vote for a 96-up gen 6. Use the L29 heads with a 454HO cam. Factory GM roller cam. Be about 425 hp. Thing I like about GM cams is they are designed to not beat up the stock valve train. GM REALLY doesn't like to give away free motors. Or go a little hotter with a ZZ502 cam and some rectangle heads. Still be around 9 to 1 with factory flat pistons. Replace the orig roller lifters. I got one of these for 200 bucks cuz lifters started coming apart. Over 100k and no ridge or measurable bore wear.

 

The stroker small block is probably the best option. A lot of your total budget would otherwise go to the new mounts, pullies and brackets etc etc etc for the big block or the LS swap. No cost savings there. Roller block would be cool if you find a good core. Flat tappet block would work fine too.

I am actually building a 383 now because I have time and a few parts aquired over time. Not in a hurry.

 

383 makes sense.....
LS swaps 60% of the time make great Facebook marketplace project ads......
Big Blocks are nice but would cost big $$$$$.....

Think about it......it would cost almost exactly the same money to put a Gen 1 small block in a say....2015 Camaro as it would to put the LS in the Vette. Don't be fooled by magazine ads.......every finished LS swap I have ever seen cost north of 5k and that was with a junkyard engine.......

Jebby

 

All good points made above. To summarize - in increasing order of cost and complexity: 383, big block, LS.
With a $4K budget, the 383 is the way to go for sure. I have a low budget 383 in my car. It is docile on the street, doesn't run hot and it will smoke the tires at will and run 12.30s quarter miles all day - and I've done that many times.