cv67

Have done a similar head swap didnt really seem worth it
Some Chevy vortecs would help...some AFR 180s way better
Get some compression in that thing and a decent HR if you can

Think what Krystal is saying hp/$/expectations may leave you scratching your head. Factory heads, meh.

REELAV8R

Not only the look, but the sound, the smell, the carb, it all fits the era and I like it that way as well.
New tech is amazing and can deliver so much more and it has it's place. Just not in my 70's corvette. I like to see how much can be squeezed out of a 350 by a redneck shade tree mechanic like myself.

AboveTheLogic

I disagree with the person who said the L48/L82 is hopelessly smogged out. The bottom end (especially in an L82) is fine. Do a head/cam/intake/exhaust swap and it'll be plenty fast. Aftermarket aluminum heads can be had for under $1k, cam kits are what, $250 max? Intakes are under $100 all day on eBay and craigslist, and exhaust can be done now or later. $1500 and your own labor and you have a screaming engine.

Sure, LS take-outs can be found for $1500-$2000, but that's not just a bolt in swap. You have to make all the belt driven stuff work, optionally convert from carb to EFI, and deal with the transmission compatibility (maybe this is minor for an auto, not sure). This is all in comparison to unbolting old parts and bolting new parts in their place.

I'm confident my '75 casted 4-bolt 355 makes more power than a stock LS1 that you could get for the same price as what I put into making my engine what it is. Sure the LS1 has more potential, but all that potential comes with more cost, and I don't see the need to make more then 350-400hp.... which by the way is DOUBLE the power over stock.

ykf7b0

I did pretty much the same thing with my 76 L-48 except I used 64cc Vortec heads with .015 shim head gaskets. I went with a 2 1/2 inch exhaust and also I rebuilt and tuned my q-jet with the help of Cliff Ruggles. I can't say for sure how much horsepower increased but I can tell you it was very noticeable. I'm guessing it was anywhere from a 50 to 75 hp increase. Well worth the effort! I know a cam change would really wake her up but I had a broken collar bone at the time and just wasn't up to the job.

Krystal

Money will fix anything......but $3,000 into a smog motor? Why do that.......you're already in crate motor money territory if you'd be willing to spend tht much in the effort.

I didn't say "toss 'em all".......but you do see in this time period of the mid to late 70s a lot of car/engine combinations that YES....you really should just "TOSS" as opposed to spending good money after bad.

....and I don't equate the entire car with it's engine ........ If you like the car...... you have decisions to make, IMO. Unless you're actually willing to accept a car that doesn't have even modern sedan acceleration performance here in 2016.

Again.....early 70s and older......an original performance matching numbers motor still in place is hard to argue against keeping in place.

But when talking about a '79 Corvette or any other GM car from the smog era of the 1970s is all about how you look at them.

Glass half full vs half empty?

The fact that some folks want NOTHING to do with these cars because of the perceived lack of performance......can be a huge advantage.

Which car do you REALLY want for a DRIVER?

A chrome bumper Lt-1 1970 Corvette with it's original engine in place is worth a lot more than any rubber bumper C3.......but if you just want a good looking DRIVER......there is a lot to like in the later model C3. Buy the smog car in GREAT SHAPE for 1/2 the price of the more market desirable Chrome bumper car also in great shape and spend some of the money saved on a kick *** crate motor........ the later model car still isn't worth near what the earlier model car is worth but it'll run circles around that more "valuable" Corvette.

So yeah........I have no problem with the suggestion dump the "TURD" motors...... there are better more cost effective ways to go than trying to make a sad smog motor into something it was too hobbled by the emissions standards of the day to be from the start. It's not that it can't be done.......it can........it's just that it costs far too much vs. what you have when done in my opinion.

It's not like I'm just throwing spit ***** and ideas here.

I've owned my own '79 Corvette since 1980......... I've considered all of this over the years and actually put money where my mouth is on this one. Never once regretted the decision to cast aside that original engine as too expensive to do over vs the alternative crate motor.

NewbVetteGuy

$3,000 into an SBC 350 to get decent perf out of it; no that's silliness.

Pickup a pair of Vortecs and some felpro 0.015" gaskets for $400 and a cam kit for another $300 and you'll have gobs of torque and 350 hp easy after replacing the exhaust. DONE $700 plus labor.

If you've got an L48 iron intake then get an ebay / CL intake for $100-$150 more.


No matter what you do; even if you buy a crate motor, you'll need to buy new exhaust -this cost is factored in for both the existing "smog" motors and a new crate motor.


The only thing wrong with the smog era motors that makes them different from any other early 350 is the crap exhaust and the crap heads. (And the rating system that makes you think that the situation is much worse with the smog era motors and the equivalently over-rated crate motor ratings.)


If you want a roller cam; you should get a new roller block crate motor, though. Many crate motor also come with "meh" heads.


Adam

keithl1967

Not really prepared to do a cam swap...if I were, Id go retro roller, like I did when I built the 406 in my camaro...but then I'm into $1K plus, with new lifters, cam, valve springs, etc...

again--was thinking I might be able to upgrade performance modestly with parts I have hanging around...

Honestly, I was trying to avoid the snowball effect...If I were going to get into the cam swap (while also doing the heads), at that point, I may as well just rebuild the bottom end, too...

keithl1967

Or at least re-ring the bottom end...

Jonz79

Krystal,
This is car 33 for me. I was probaly turning wrenches when you were playing with Barbies. If folks like you had their way, there would be ZERO Classic Cars. Your line of reasoning, which contains no reasonable thought, flies in the face of much is represented on this very forum, and is in direct conflict with a great number of folks who strive to preserve these cars, regardless if the year of manufacture. You in short, are a snob.

What a silly, uninteresting world it would be if under the hood of every Corvette, lay YOUR personally approved, worthy engine. Your disdain for everything post 74 is pitiful. Do us a favor, and scramble over to an LS forum to boast about laptop tuning. I'll be enjoying my beautifully preserved, 1979 Corvette.

NewbVetteGuy

You will have the same amount of labor to replace the heads regardless of what heads you go with; might as well make the labor worth your while by getting an appreciable amount of performance out of it. Selling what you have already and getting vortecs would get you more performance for your time and money / resources. -If you don't want to replace the tiny cam and lifters then get some 1.6 rockers to get a little bit more valve lift out of the cam you already have.

The bottom end is a whole different universe of labor and cost; don't let the snowball roll down the hill that far...


Adam

keithl1967

Interesting....I had not thought of adding 1.6 rockers to the mix...Can't believe I didn't, but nonetheless, I did not...

That might provide a better bang for the buck (all else being equal) than most other pieces (assuming no MAJOR changes)...

Team Lazy

I'd like to hear from the anti original block crew, exactly what is the difference between the smog motor, and the other million of SBC motors that have been the backbone of hot rod ding since the 50's? I mean, I've removed my smog crap, and for somewhere in the area of $2k will be around 350hp, and it's going to be a fun cheap hot rod. I already enjoy it more than my Z06 in a lot of ways. Which, incidentally has an an LS.

But if I'm reading it right, you keep saying the "smog motors" as if that's a thing... Explain please?

AboveTheLogic

They're talking about the crap heads that came on the smoggy SBCs of the late 70s and 80s, and the tame cam in the L48. The bottom end is fine, and much of the low compression can be cured with smaller chamber heads which flow better.

Take any smog SBC and install some decent heads with a matching cam, intake, carb, and exhaust, and it'll be plenty fast. I looked into the L82's cam specs recently and it's not bad, I guess just timed a little weak.

Krystal

It's not that you "can't" make something worthwhile out of a smog motor from the dish top piston, smog head, early days of pollution control era for me......... it's more a matter of not being able to do it cost effectively.

Sure better heads with much smaller combustion chambers, a hotter cam, new intake and carb could get you to more power........but to do all of this to a near 40 year old motor requires you to trust that all is well in the bottom end.......because if you are going to tear into the "short block" itself.......I'm betting your going to get into a price tag that could leave you with regret over what you have when done vs what you could have had for the money.

Despite what was supposed to be stinging rebuke of me as a "snob" a couple of posts back.......nothing could be further from the truth.

I'm a realist who recognizes that today it's much more difficult to make a case for "hot rodding" a smog motor. In a world where a company like "Blueprint" engines will sell you a complete 383 with aluminum heads and a dyno sheet proven, roller cammed, 430HP small block that comes with a pretty impressive warranty for what amounts to a dollar figure you'd be super hard pressed to match.......it just doesn't make as much sense as it once did.

You don't have to go to a computer managed motor with all the expense and effort that requires at all to get significantly more engine at a reasonable price point. In this argument alone you find plenty of reason for caution before plowing too much cash into a forty year old engine that doesn't carry that "matching numbers" price bump to the old car it came in originally.

Krystal

I'm going to say simply this:

You're DEAD WRONG!

Like you I also own a '79. I'm far from advocating for a computer controlled solution for anemic HP in an engine that started out it's time as a SBC weakling, too hobbled to compete today. My car sports the solution I talk about in a crate motor and while a computer controlled engine would have likely produced a more compliant "driver".........I don't drive my car enough to really NEED the better MPG a really modern era motor would have gotten me. The Holley carbureted engine in the car now is NOT an LS motor. Those come in crate form too.... but now you really are in the realm of a far more expensive answer to the weak HP problem that would have been hard to justify in a car that hasn't seen much more than 500 miles driven in any summer over the last 18 years or so since it got an extreme make over. In anything but a daily driver it'd be near impossible to justify in my view.

I'm far from a snob on this one. These are simply MY OPINIONS....you don't have to agree..... but calling me out as a snob is far from accurate here. As always I'm focused on getting the most from the money I do spend on the car. Your priorities may not match up. That's OK........the world of cars will always be interesting mostly because of our differences.

If I really think about it.......I consider myself very much in the middle of the road on this one.

On any given Sunny Sunday......I can see old cars on the road driven on a small budget and I'll see cars I can't imagine how the owner got to a place where they have pretty obviously got 2-3x what the car would ever sell for into it.

There are no snobs in this hobby/addiction. Just various degrees of willingness to spend money on cars that are almost always more of a toy than any sort of practical transportation.

In the end I'm a budget minded person who rarely enters into any venture that involves spending extra money or my extra time without a plan thought out from all the conceivable angles I can come up with first. For me.....just me.....you can do what you please....a crate motor was an easy decision vs a "do over" of the original weak *** L82 my car originally came with when I got it "off the lot" in February of 1980.

SpiritOf76

SpiritOf76

I'm enjoying this thread tremendously, as I am considering the same choices... Keep my numbers-matching "weak-***" L-48, or go with a plug-and-play 383 with more horsepower than I could ever get out of my 350 without spending 3x as much... AND a warranty!!!


I love turning wrenches on my car, but it's a hard decision to make... Do I save time and money (and my knuckles) and buy a new motor, or do I do the work, bit by bit, dropping in new parts as I buy them, and earning the satisfaction of improving what I have by doing the work myself on my original motor?


I'm really torn. I see both sides of this discussion as valid, and both are appealing in their own way.


I'm pleased to drive the car the way it is with it's sleepy, 40-year old, undesirable motor. I just want a nice cruiser that's fun to drive, sounds bad-***, looks pretty, and is reliable enough where I'm not worried to venture more than 20 minutes from home.


BUT, it's also nice to have that extra OOMPH when you feel like getting on it a bit... which right now is VERY lacking. Can I get that from my L-48? With enough money, probably... but where do I draw the line? Or do I just buy the crate motor? Ugh...

Richard Daugird

Is 350 H.P. realistic with 8.5:1 compression?

NewbVetteGuy

8.5:1 compression? with 64cc combustion chamber... doesn't sound right... -Weren't the original heads 76cc chambers?



Adam

Krystal

There is an appeal to the Rubber Bumper C3s that a lot of owners of the "more desirable" Corvette don't always immediately understand.

There is a measure of FREEDOM in a car that isn't valued mostly on it's originality of the components within in it.

You can do anything you want in the way of a better than stock motor and see no real downside to the value of your car.