Jims79

OK don't go telling me to search old threads I just what to ask a few questions & get a few good answers.

Should I rebuild my L48 (try to save a few $$) or should I replace it w/a crate motor? Budget is around $1,800.

If I rebuild it can I do so w/out spending more $$ then the crate and can I get 300hp or close to 300hp out of an L48?

Is the L48 worth rebuilding? if not is it worth saving for # matching? My garage space is limited.

Last Q is an old running C3 Corvette motor worth anything to sell?

Thanks
Jim

Gordonm

I'll take a crack at this. The L48 motor is just a common everyday motor. It was installed in many Chevys not just Vettes. So its worth is about the same as any other running SB Chevy. You can get 300 HP out of an L48 with some cam and head work with a good intake and exhaust. 1800 is a budget rebuild and you won't be able to buy to many Hipo parts. That would just about cover all the machine work and some of the needed replacement parts. You can get a low performance crate motor for under 2000 but I think the HP is rated around 250 HP. I'm sure others will chime in on this.

markdtn

For $1800 you can have decent machine work plus parts assuming nothing major wrong with your old engine. You can use one of the $159 350 kits from Northern Auto, a good cam (you'll get new lifters) and I would get a FelPro gasket set. Figure $500 machine work, $300 engine kit, cam, and gaskets, $550 for new Vortec heads, $200 for a Vortec Intake, and $300 for tuneup type parts. It would be possible to get it in there for $1800 doing the work yourself. Next best suggestion is buy a crate Goodwrench 350 and swap in a new cam. That would be like $1500 or so but the original block and Vortec heads would be a plus to me worth the difference in price.

If it is me, I'd keep the original motor for posterity. Drain it and hide it in the corner of the garage or under a table. Once it's gone, it's gone. Never know what the next owner will pay extra to get. As far as selling it now, a running 350 L48 is probably worth $400 tops.

77Blue

I look at it this way - will you get more enjoyment out of having the original (and telling people it's the original) or talking about how you dropped in a crate motor. You can make the performance and cost be similar.

jdmick

If you don't do the rebuild yourself I think you'll have a tough time making 300+ HP for under $1,800. Here's a suggestion. Buy the cheap $1,400 260 HP crate and spend what's left on swapping your rear gears for 3.55s or 3.70s. If you've got 2.73s or 3.08s now you'll feel the difference more than you would 40 HP. Plus you can always do a cam or head change later as funds allow.

Easy Mike

If the L-48 is original, keep it an rebuild it. The original engine will increase a potential selling price at a later date. If you have average mechanical abilities and a place to work, you can rebuild a small block Chevy for way less the $1800 and only have to farm out the jobs you cannot perform yourself.

panic

i had an L48 on my '77 corvette, i've tried a lot of mods but with no real results, i've even supercharged it!! no way, this engine is like a company dog, you won't get a dobermann out of it even with the best trainers...

Boofers

300hp is not that big a deal to achieve. I dyno'd 240rwhp from my 1977 L48 with the following mods:

- Comp Cams H268
- Hooker Comp headers
- Dual 2.5" exhaust, high flow cats, Magnaflow mufflers
- Weiand 8004 intake manifold
- Recurved stock distributor using Lars papers
- Retuned stock QJet using Lars papers

When I can afford it a set of heads should get me another 30rwhp or so. If you don't have all the money right now you can slowly upgrade your engine. For example do exhaust, intake & cam one year, do heads the next year, etc.

Besides money, you need to think about how much time you have available to read, learn, do the work, trial & error, make mistakes and be frustrated. It is a lot quicker & easier to drop in a crate motor plus they come with warranties.

The major benefit of rebuilding is all the experience, learning and pride you get out of doing it yourself. That way when you go to car shows or you're at the coffee shop you can talk with the guys about the shot valve springs your heads had or how out of round your cylinder walls were.

77TSi-meez

I have 400ci sbc, 4 bolt, aluminum intake, holley carb, 325 hp 4 sale

Pauld

With respect, you obviously dont know what you are doing. At the end of the day an L48 is a SBC and with the right components, time and knowledge, you can achieve VERY high numbers. It comes down to $$$ and if you are able to do the work yourself the $$$ can be saved.

Pauld

I agree with Boofers, look at what he has done. I have also achieved simliare with, cam change, new heads, intake and carb. All this was around $1900 from Summit.
My dyno figure is 269 rwhp and thats a good increase from stock

Jims79

Thank you everyone. You gave me alot of good info to think about. I guess went I pull the L48 this winter & take it apart that will help me deside to rebuild it or swap it out. The L48 doesn't smoke or burn oil and runs pretty good. But I had a compression check done & the # 2 & # 6 cycl are 20lbs lower then the rest?? The other symptom is when the engine reaches 220 it rocks like I have a big cam?? Which I don't?

MotorHead

You can get 300HP from it with flat top pistons (10:1CR) and a good cam and intake and headers.

I got 296HP and 327Tq at the rear wheels with my L48 with a half decent set of heads

TheMongoose

I've been considering the same thing. For $1500-$2500 you can get the 5.3L (about 327cu) chevy LS1 style motor. It's 295hp as is. With a LS1 intake for $20, cowl induction, no cats and headers you should end up with 300 rear wheel horsepower plus get 25-30 mpg doing it. No carb tuning(an ancient sport) and no raw gas smell occasionally. I agree with an earlier quote which was to stuff the L48 under a table and keep it to get a few extra bucks if you ever sell it(the car that is).

73'454folendore

I yanked my L48 out of my 73' and dropped in a 454 and it was the best moved it ever made. If your looking for performance pull it and set it in the corner of the garage. If you just want to look pretty then keep it and do the upgrades.

bobs77vet

Jimmy have i got a deal for you.....why don't we build that two bolt main i got from Chris thats sitting in my garage it cost me $75 and we can use what ever was good that came out of my old engine. You can keep your numbers matching motor that runs ok and we can build a monster out of the one in my garage. Chris can help us with any problems if we run into them... we can build the engine in my garage but the swap has to be done in your garage. . but you can use my lift etc....

Steve439

panic

hi pauld, i was referring my personal experience with my L48 , of course i dont know much about american engines yet like many of you do but i'm learning ...
when i say that the L48 will never be a winner i mean exactly that, dont forget we're talking abt sports cars here and not about boring shopping toyotas or hondas or whatever , the L48 and the mid 70' vette models were just the shadow of a real vette, heavy/no performance apart from the 'performing look' and a ridicolous suspension package...all due to an arising and cinic 'political correct' way of reinterpretating sports cars...
did i go too far?

Lee H

Many people had this same question 10 to 15 years ago. Now numbers matching on older corvettes is a big deal. C3s will be in the same boat in about 10 years. As with C2s, a numbers matching motor adds value to the car, a C3 with a numbers matching will be more valuable. Hind sight being 20-20, I would bag the original motor and put in a GM crate. Many options to choose from, lots of horse power at a reasonable price with a great warranty. As time and money permits I would rebuild the original motor being carful to perserve the the stamp pad. JMO

45ACP

What makes you say that?

The small block Chevy is extremely easy to modify. Anything from mild to rip-the-wheels-off-the-ground type performance can be had.

My car was born with an L48 and I must say it responded very nicely to modification.