REELAV8R

For me it's was an easy descision to keep the L-48 block and build from that.
There is a bit of satisfaction in building your own engine and being intimately familiar with each and every component in that engine. Barring any errors made in assembly or modification, if applicable, you are going to know exactly where to go in that engine to trouble shoot or tune to your liking.

It's that knowledge that confidence in knowing what exactly is in that engine that allows you to push the envelope, and know that it can take it or not.

That's why I build my own. I know very well what it can tolerate and what it cannot based on the quality and nature of the components used and who put it together (me).

NewbVetteGuy

EXACTLY. The heads and exhaust are crappy and the from-the-factory cam timing was poor for good low speed torque; that's the difference.

You could of course correctly argue that the early blocks are "crappy" for building a high performance engine as you need to buy expensive retrofit roller lifters and cams; but really you're just saying that they make high perf more expensive.

You could argue that the earlier blocks were made of lower quality castings and materials so they won't last as long and there are large failure rates when you get to 0.060" overbores.

But that's about it, as I see it.



Adam

NewbVetteGuy

I agree. I plan on keeping the stock block as long as I can; and why wouldn't I?

In the nearer term, I'm giving it a new top-end with new heads, intake, and retrofit roller cam. Not insanely cheap, but not that expensive, either and with an estimated 425 hp / 425 ft lbs VERY reasonable power for the money and labor.

In the longer term, if something major happens to my engine, I'd be looking to overbore it by 0.015-0.030" and make it an internally balanced 396 stroker (technically a few cubes short of 396 with only a 0.030" overbore).

I know the block is good and I know it's only got 14,000 miles on it; I know that 1 in 10 of these old blocks can fail the pressure test when made into a stroker, but given that I know where thsi block came from and that the car's been babied and it's only got 14,000 miles on it, I think the odds of success are much higher.




People really need to cut through the crap and get specific around what's wrong with these motors and what's right with them and make an informed decision. If you've got a good bottom-end, put some good heads on them and replace the exhaust and you'll be doing as good or better than most low cost crate motors for far less money. -Plus don't forget if you buy a crate motor you're STILL going to need to replace the entire exhaust system. --If you want to go with a hydraulic roller cam, then yes the cost gets more expensive there, but if you want to stick with flat tappet, then that's even more reason to stick with the old good bottom-end.


Adam

NewbVetteGuy

SpiritOf76, don't be beaten down by the "tyranny of "OR"; instead, seize the "opportunity of "AND"! By that I mean keep your numbers-matching weak-*** L48 and make it a 383. -It requires long-term vision and persistence and patience, though. If you want instant gratification; then crate stroker 383 all the way.

1. Make sure your bottom-end is in good shape; find out if it's ever been bored -if not you can do a 0.030" over-bore when you go to the 383 stroker and leave an extra 0.030" for later.

If it is good; proceed to #2
2. Get a great exhaust system for your C3 including coated headers (to help keep down temps for when it becomes a 383 later and to let you push the CR as high as possible without detonation later

3. Replace the top-end; newest generation heads and CAM -64cc / 195cc Profiler heads have great flow at all lifts, highly efficient chambers and with a Felpro Gasket and a stock L48 bottom end get you to like 9.8 CR or there abouts- Get em from ATK Engines for $575 each fully assembled with normal height exhaust ports so they work with your headers from #2 above- the 195ccs won't give up too much bottom-end with an appropriate CAM and can make for a great high torque 383 build when you redo the bottom-end in phase 4

4. Stroker time! Freshen the block with a 0.030" overbore and get a nice internally balanced and reasonably priced cast 383 stroker crank and hypereutectic pistons with total seal rings- You'll have loads of power and as long as you keep the RPM at 6,000 or lower a cast crank and hypereutectic pistons will last. -Now you have to get a new, bigger CAM (if you went with a hydraulic roller cam in #3 you can reuse the existing lifters now; YEA for hydraulic roller lifters!) and the pistons will need to have a small dish to keep the CR in the safe range with the 64cc heads(keeping the quench ideal means having the machine shop deck the block while they're boring it); but you'll have a beast. -Get a new oil pan that's appropriate for a stroker while you're at it.




You can move from step to step as money becomes available and you'll have a beast of a "Numbers Matching, Smog-era 383 Stroker".

-Hell you could even go with Dart Iron Eagle heads and the original valve covers and the thing would be numbers matching and LOOK stock and easily and conservatively end up as a 450hp/450tq motor. (Flywheel in case that's even remotely in question)



Adam

Krystal

I think the term is/was very useful in describing any 350 built in the late 70s. You don't hear it as often today as you did in the 1980s when more of these late '70s era Chevys were still on the road.

"SMOG MOTORS" were hobbled by the need to beat the tail pipe test before Chevy could do that and make power as they can today.

The term was a "buyer beware" warning to anyone looking to do a build up of an SBC......."not much to work with here". Just about everything is marginal at best and some pieces are hopeless and will have to be replaced rather than just reworked.

Throw enough money at any motor and you can make racer out of it......the real difference for me comes back to which are the most cost effective candidates. A L48 build up with realistic limited expectations could make sense........but I really wanted a car that couldn't be smoked by my daily driver on acceleration.

Krystal

That will be a GREAT motor when it's done........but I do wonder if you can beat the price tag on that BluePrint motor. Have you actually gone the distance on this one and added it all up for real?

Parts and Machine shop services in my area are too expensive to make this work ......believe me we went back and forth, up and down, inside and out trying to make it work......we couldn't do it.

I wish we could have. My husband rebuilt the 302 in his '69 Camaro and I would have had him do my car too......... but the numbers just didn't add up even with what is essentially "free labor".

Richard Daugird

I was just looking at Blueprint Engines website, looks like some pretty sweet deals. $3,800 for an aluminum head, 430 HP/450 FT LB roller motor is not too shabby. Have you any hands on experience with them? Would be a Hell of a lotta fun in a street car! I wonder what it would cost to get that out of a junkyard LS? One of my helpers from work has an LS in his street truck, I think he said it dyno'd about that at the rear wheels through an automatic(probably a 4L80E).

tabbruzz

the mods in my signature woke up my 79...

Krystal

Better heads, headers, aluminum intake and a Holley performance carb........ this combo will even give you 9:1 compression........ it comes in super cheap in cost if you already own the heads....... but it occurs to me you can't get the full benefit without a cam swap. A mild performance cam and new lifters would add very little extra cost yet allow your combination to actually work to it's potential.

Slapping on the parts you're talking about will mostly benefit the ability to find more mid and top of the RPM range power vs. the mid RPM peak power the emission prioritized cam your L48 came with. That stock cam will never allow the potential of your combination to be fully realized. No guessing required. Call up a reputable manufacturer like Comp Cams, tell 'em what you have for parts, transmission and rear gears......they'll get you set up with the best cam choice.

You can't get serious power out of this combination, by today's measure, but I wouldn't be surprised to hear you could add it all up to an extra 30% over stock power and you almost certainly get an engine that can pull more power to 5,500-6,000RPM.......sure has to be a lot more fun than the L48's weak sub 200HP and power that flattens out entirely well before 5,000RPM.

Not sure why you're even asking this question........'it's pretty clear you already know all this...... you have all the right the parts in hand or in mind already.

cv67

Krystal is right on the money

Modding an LSX is not cheap and stock they arent all that hot....conversions arent cheap either

All up to what you want out of a car
Plenty of parts out today to make a Gen1 run hard without getting too carried away.

Richard Daugird

You ran 12.7 with 8.5:1 compression? Impressive!

"L-48 auto, 3.55s, headers, holley carb, intake, comp cam,, vortec heads, Jegs torque converter
12.71 with a 1.74 60' at 105+mph"

Kacyc3

FWIW sell the heads, get vortecs or aftermarket, bump the exhaust up to 2.5". These parts you can use later when it isnt enough power or the bottom end lets go.

68post

He probably started with around 7.9 to 8.2 actual compression, and ended up with an approx 8.75 to 9.0 compression. Because of the smaller combustion chambers of the vortec heads.

BUT.. ..still impressive !

Krystal

It's more than impressive........it's flat out amazing. I wouldn't have expected that'd even be possible on the changes he's listed. This makes his car as fast or faster than most modern LS powered Corvettes. He's flat out STOMPING LT-1 1970 Corvettes, the benchmark for 350 small blacks of the Carburation era.

Somehow he's getting a whole lot more out of the combination than I'd ever have believed possible. Makes me wonder how much weight he's managed to pull out of the car.

Krystal

It is a kick *** deal for sure. It's not for the pure hobbyist or car guy who really wants to be able to say, "I built it myself". But from a money perspective it's pretty tough to beat if you have to get all the parts together and then do the machine work as well.

The LS swap has become pretty popular and there are lots of donor cars out there........but for me I already own the Computer controlled daily rides.......I like my old Corvette for the throw back in time that it is. Carburetor and raspy idle .......may not be as efficient but it's all part of the experience on a Sunny, Sunday drive in the summer.

0BluePrint Engines

Hello Keithl1967

We saw your post here and thought we could point you in the right direction. From what I am reading your Corvette has a very good condition, low mileage L-48 350. Unfortunately, these engines were not near the pinnacle of performance for GM. The L-48 was available in the Impalas, Monte Carlos, Camaros, and Pickups during the '70's, being a 4 bbl with factory dual exhaust until the catalytic converter came along. The L-82 was the Corvette exclusive with a bigger cam. They were weighted down by poor head design with lousy combustion chamber efficiency, low compression, EGR's, AIR pumps, and a bazillion vacuum lines.

Believe it or not, the 461 castings and the 882's share the same intake port designs, the 461's being the winner with much better combustion chambers. But still, they are a 50 year old design. Cylinder head technology has marched on since then. There are tons of really good, affordable aluminum heads on the market that will be the biggest boost to power, including our own 195cc heads.

If your current engine is in good shape as you say, then you really only need some bolt on's to really have a much more fun car. Do a compression and leak down test first just to be sure it is a solid foundation.

Heads, cam, and good exhaust are you need. A few members have followed this plan and are happy with the results.

For a camshaft, we have been working with Comp Cams for 20 years and recommend. Their Extreme Energy line produces great power and sounds cool as well. For a 350, their XE274H flat tappet, or their XR276HR would work great.

Your Edelbrock Performer intake manifold will work, along with your Quadrajet 4 bbl carburetor and HEI distributor. You can upgrade the distributor with a hotter coil and module for more performance. No need to buy new stuff there.

I hope this helps out. Keep the hobby going, guys!!

Scott Liggett
BluePrint Engines
1(800)483-4263
info@blueprintengines.com
www.blueprintengines.com

Richard Daugird

I like that he gave you sound advice without trying to sell you a complete engine. I will be remembering that...the kind of man I like to do business with.

AboveTheLogic

Yeah that's the kind of help that steered me towards buying Blue Print heads. I went with the retro roller kit and the XR276HR cam. It is a screamer. If I had to do it all over again, I probably would have stuck with a flat tappet cam. The roller cam was a hassle. Definitely do your homework if you're considering a roller cam.

Krystal

......but can't say I'm surprised either. His company sells parts and complete engine packages at super competitive prices.

When you sell a GREAT products at Great Prices......the "hard sell" isn't required to make your targets for sales!

cv67

Blueprint should hire Krystal to be their online pr person
Woman who has a clue...and a 10 to boot.