How can I make my 1977 L48 4 speed faster?

[leeboy66]

I want to make my 1977 L48 4 speed faster!! The car is completely stock and I want to make some changes. What modifications should I do first? I was thinking of getting headers and a true dual exhaust first, but I'm not sure if that will make much of a difference in horsepower. My car has a stock 3:36 rear and I was thinking of getting a 3:70. What mods would increase horsepower the most.

 

[blackandred78]

Here's what I did to my 1978 L48 4 speed...

- open element air cleaner (purchased out of Mid America Corvette catalog) with K&N air filter
- roller tip rockers
- synthetic oil
- stainless steel braided, silcon wrapped plug wires
- Bosch Platinum plugs
- high flow cat
- enlarge pipes from 2 1/4" to 2 1/2"
- DynoMax mufflers
- Edlebrock 795 CFM carb
- aluminum intake manifold

These are almost all easy bolt ons - and I kept all of the original pieces just in case...car really came alive and feels quick and sounds quick. I gained real speed and documented most of it on my G Tech meter.

I've played with suspension as well - composite rear leaf spring takes huge weight out and gets power down better - aluminum manifold is big weight savings - remove air pumps, etc.

Mine has 51,000 original and documented and is a blast!

I would also like to put in an electric fan to reduce engine drag, and install a lightweight flywheel and performance clutch - but won't do that until it pitches...

Have Fun!!!!!!!!!!

 

[TJay]

$$= HP, headers & duals will help it breath, and thats what is needed to make HP. So it's not cheap but you need to change those L-48 heads, intake & carb. Get the engine breathing, my 79 is the L-82, now running 370+ HP, (RW Dyno) but it took alot of money/parts and my time. If you can't do the work yourself, buy a new crate motor. But heads, intake, carb, headers you should be able to install or find a friend that knows how.

 

[IH2LOSE]

Going faster is a sickness as it seams the faster you go, the faster you want to go.

So my questions are

Do you have a budjet

How fast do you want to go

 

[leeboy66]

I do not have a budjet..what is it?

 

[blackandred78]

Personally I wouldn't spend the dough on headers and heads...while it would be an improvement, it is tough to undo should need to be to return it to stock, and is really expensive. The L48 is pretty low compression and just needs to breath better - the open element air cleaner and exhaust were the biggest improvements on mine - and easy/cost-effective. Car looks great in yellow by the way...

 

[IH2LOSE]

The word fast is too fauge

If your looking for seat of the pants throw you in your seat. I would suggest 4:10 gears but what you trade off is high way cruising and fuel economy.

Your motor in stock form is 185 hp so with out trying to sound rude, its a little anaemic. I have been playing with cars forever and been thru the trying to make it faster routine several times and have learned from my prior build that I am never satisfied with the little bolts on as they just never give neck snapping performance.

My suggestion would be a stroker small block up in the 400 hp range that you can dress up to look like an original motor.

Best of luck with it

 

[Jack]

True dual exhausts, cam and recurve your distributor ... as a package.

L48 cam specs about .390"/.410" 194°/204°dur@0.050" ... utterly wimpy cam.

Cam&lifter kit like Speed-Pro KC1013R (.443"/.465" 214°/224°dur@0.050") would do nicely with your stock compression, 4spd & 3:36.

Your OE intake manifold & your OE carb (if in good shape) will be fine.

 

[SPANISHVETTS]

Cheap, quick and totally reversible; Drop in a crate 383 and put the L-48 on the shelf. If it is ever time to sell the beast stick the L-48 back in and make the new buyer happy with an all original Shark.

If I took my own advice I would be thousands of $$$ ahead. It seems like every time I open up a small block $5K slips out of my rainy-day/play fund.:eyerole

 

[AKRAY4PLAY]

how much money do you have to invest in speed?? how original do you want to keep the car?? most mods are reversible with no perminate damage as long as you keep the original parts. it can be made to turn low 10 second 1/4 mile runs if you have the cash.

 

[leeboy66]

I can't spend much more than $2,000 right now. I'm looking to increase horsepower without rebuilding the entire motor.

 

[SPANISHVETTS]

It is a bit over budgit but it is complete and comes with a 2 year warranty. If you amortize the cost over the 2 years of the warranty it will cost you less than $170/mo. and you still have the L48 in reserve.

 

[Sensei]

I've done pretty much every mod in the book, heads, cam, intake, ignition, carb mods, flat top pistons etc. etc. etc... But the absolute most bang for your buck / feel it in the seat of your pants mod was the exhaust system. I replaced the stock headers 2" 2-1-2 exhaust with a pair of short ceramic coated headers into 2.5" true duals and the difference was NOT subtle! The whole change cost me a total of around $350 (if you are interested in the details of how I did it for that much, let me know) God bless, Sensei

 

[Evolution1980]

If you MUST do something, do the intake and exhaust. (Make sure you don't need to pass emissions!) Not much else will be worth the time and investment.

Dump the single or dual snorkle intake, go with an open-element as already suggested. Get rid of all the emissions BS, such as the air-pump and all that other stuff. Get rid of the cast iron headers and the front & rear Y-pipes.
Put on some Hooker Comp Headers, and run some exhaust straight back into some free flowing mufflers.
Don't replace your stock Q-jet 750, but have it tuned ("rejetted") by someone that KNOWS Q-Jets. Rejetting a Q-jet is cheap, but unless you have a dyno, it's a trial & error process.

Now, the BEST thing you can do... save your pennies for another year (or just don't do anything else to the car). When you have the funds, buy a crate engine ZZ4. Then you'll be happy. The reality of the situation is that with the L48 engine, it just isn't going to be much of anything without an entire rebuild from top to bottom. And by then, you are into crate engine prices. Take it from someone that's been there / done that.

The exhaust and intake mods you do (if you do it) this year will easily transfer to the new crate engine. So that'll be one less thing you'll need. When it comes time, the crate engine will just about be a plug-n-play upgrade. You'll be happy you waited. But in the meantime, the power increase AND more exciting sound of the intake/exhaust will help you get by.

 

[Art Jett]

How did you do all that for $350.00? I just priced a set of Hooker block huggers, ceramic coated and they were $400.00.
Art

 

[Sensei]

Okay, here's what I did:
1. First off, ask the local hot rodders where to get custom exhaust work done. Typically, if you go to a Midas type shop, the will only want to re-do it stock. Even if they will do the duals, they will want $500 just for pipes and mufflers. But if you ask around enough, every town has a shop where quality work is done at a reasonable price. I got a guy to do my custom 2.5" aluminized pipes with O2 bung for $125. (Everybody told me he would be around $100, I think the extra $25 was because it was a Vette.)
2. I got a set of summit turbo mufflers that were about $20 each. These look stock, have a nice but not too loud rumble and flow well.
3. I know I'll probably get flamed for this but, I got my headers off ebay. (I don't buy Holley products ie Hooker, long story) If you do a search in ebay parts for "ceramic block hugger headers sbc" you will find them for $130 (+ around $30 for shipping). The quality of the metal and ceramic coating is good, but you will have to do a couple of things for fit. I had to buy four stainless allen head bolts because the standard hex heads they came with were too close to the pipes in some places to get a wrench on. That was the easy one. The bigger challenge was that the tight tuck design just touches the driver's side motor mount. I took a sledge and "massaged" a spot just after the primary tubes came together. I was worried that this had damaged the ceramic coating, but I took them off about a year later when I did my engine rebuild and they still looked like new, no rust. Someone quoted me a price of $350 to install the headers, but my 16 year old son and I did it in the driveway on a Saturday. An enjoyable and satisfying afternoon's work! I put a short peice of pipe on the header and drove it to the muffler shop w/ open exhaust (really loud).
On the way home, my son was very excited about the difference in performance (I have not let him drive the car without me in it since). God bless, Sensei

 

[Glensgages]

If you want to make your Corvette 'quicker' (not 'faster' as-in top-end speed, but 'quicker' off-the-line ), consider a swap to deeper gears (3.70, 3.90, or 4.11s ), that give the car more 'omphhh' at all RPMs, no matter what motor you are running:
it is torque-multiplication, and almost all future updates/mods will like the results, too, because they all make more HP at higher-RPMs.

 

[Evolution1980]

If you want to make your Corvette 'quicker' (not 'faster' as-in top-end speed, but 'quicker' off-the-line ), consider a swap to deeper gears (3.70, 3.90, or 4.11s ), that give the car more 'omphhh' at all RPMs, no matter what motor you are running:
it is torque-multiplication, and almost all future updates/mods will like the results, too, because they all make more HP at higher-RPMs.

...at the expense of highway cruising RPMs and top speed... (but we all already know that...)

 

[leeboy66]

Evolution, what type of gears do you have on your Corvette?

 

[Evolution1980]

Evolution, what type of gears do you have on your Corvette?

I have the stock 3.08 rear end. The 700R4 essentially gives me a 3.73 in first gear though...
Highway crusing at 70mph is right around 1850 rpm. The difference from 65mph to 80mph is about 350 rpm in OD. It gets real easy to accidentally creep up from 65 to 80... :L