szercer

Anyone want to give an educated gues of the hp, 0-60, 1/4 mile times my vette will have after mods? It's a 76 L-48 4-speed 200hp stock?, I'm going with magnum rocker arms supposed to add 12-15hp, I'm gonna have a muffler shop make pipes from the headers to mufflers (2.5"), no cat, hedman headers, K&N filter, K&N 14" x-treme top or whatever, and probably KBD free flow mufflers, I want to avoid the cluttered muffler look from the back if possible. also does anyone know if the K&N filter top piece(not the actual filter) helps, it's $60, any experience with march underdrive pulley sets too are they worth $200?
thanks for any help

robzr

I have a '76 L-48 which ran a 15.2 @ 89 (not 100% on the mph) when it was BONE stock (except no cat) with over 100,000 miles on it. I went down the path you are going down a couple years ago, trying a whole bunch of bolt ons to get more power, as have many other forum members.

Don't waste your time with the filter. Buy a 14x3" open element from summit or jegs or a local speed shop or swap meet, if you shop around you can find one with a filter for $20. That will feed you with FAR more air than that L48 will ever use. They look nice, and sound cool too. The rocker arm's aren't going to add 15-20 hp, but they will make a slight difference. Go for 1.6s, I ran them with absolutely no problems. Skip the cheap junk like the roller tipped stamped rockers, if you buy rockers at least get some Harland Sharps ($200). But 15-20 hp is optomistic.

The very best thing you could do is change your camshaft. It's a lot of work, about a day if you do it yourself. You probably want someone around who has done it before. It'd run you about $150 + $25 (gaskets & RTV) and give you the single best performance increase aside from new heads ($$$).

The best thing you could do would probably be to work on your exhaust. Get a set of Dynomax 1 5/8" headers and some Dynomax Super Turbo mufflers (they are about $30/each and will outflow any muffler in their price range). The "Dynomax Cat Back" is a waste of money, they charge you an extra $90 for a couple real simple bends an exhaust shop could do for half that. You can also try a Dynomax Super Cat, I just put one on my Jeep and I'm a very satisified customer. It cost me $60 (better yet, run without a cat if you can get away with it).

Those march pulleys will look real nice but you won't notice any difference whatsoever. Not a wise place to spend your money. They'll get you a couple horses if you are spinning high rpm, but at the cost of cooling and power.

Some other things which are good for that motor - Edelbrock Performer intake, you should be able to pick one of these up pretty cheap used, or $150 ish new.

You can get a re-curve kit for the distributor ($20 ish), which you set to bring your mechanical advance in faster and net you more power. It's not too hard to put on. While you're at it, get an adjustable vacuum advance for about $15 - this won't get you any full throttle power, but will help out with part throttle power and throttle response.

Most important - make sure your motor is running well. Make sure the plugs are clean and gapped correctly. Make sure the wires are in good shape. Make sure your base timing is set correctly (and you can experiement with advancing it a few degrees).

Tuning your carb would definately help, but takes a bit of knowledge. You can get a book on tuning Rochesters, or switch to a Holley which is easier to tune and parts are more readily available.

Unfortunately the way it works is the things which help you out the most are generally the hardest things to do. The ones that cost a lot of money but are easy are generally a waste of time and cash (like those pulleys).

Good luck!

Rob

tnt76vette

'76 L-48 lists at 180 Horsepower....As for the mods its hard to "guesstimate" your end results here as you are up in nosebleed territory (rare air), but you will notice a nice result from removing your stock exhaust system. Think abt maybe a cam switch if ya can....Good Luck :seeya

Aaron-74

Cam switching is a pain in the butt. You've got to pull the radiator. And while your doing it you get in the "well, since I'm here" state of mind. And then soon you in this....


so much for just a cam swap... :crazy:

joeveto

I agree with what the others have said. Those pulleys and special filters are snake oil. Depending on your skill, you may want to pull the heads and do a nice pocket port. A true dual exhaust with headers will definitely help, since the stock manifolds are very restrictive. Lastly, a cam will do wonders. If you can swing the cash, you can pick up a nice set of Vortec heads from GM for about $450-500. They come complete, and they will really awaken the engine. The more air you flow, the more power you'll make. And the engine is only as good as the weakest link. Too open of an exhaust, without a corresponding change in intake, cam, heads, etc, will do nothing for you. In fact, it can hurt your torque curve. Too much flow on the intake side, without a corresponding revision of the exhaust, will also do nothing for you. You need to take a balanced approach. Simply bolting on a set of roller rockers will net you very little.

Start with the headers. Move from there.

Good luck.

tnt76vette

Sorry Joe, while Vortec heads are indeed cheap, they must be purchased with the Vortec Intake, new center bolt rocker covers, and self-aligning rocker arms, which puts the price at least right into S/R Torquer Heads alone......and has it ever been determined that the Vortec Intake will clear our low-rise hoods? Just asking........... :rolleyes:


[Modified by tnt76vette, 2:41 AM 3/22/2002]

robzr

Speaking of S/R Torquers, there is a guy from the Jeeps Unlimited who is trying to sell a pair. Sounds like good deal I think he's asking $525 for a new pair. I'll see if I can dig up his email if anyone is interested.

Rob

GTR1999

Rob find out about the heads, I may be interested.
Gary

A C

What kind of heads does a 76 L-48 have? I believe heads almost always give the biggest improvement of any single mod. All the parts work in conjunction with each other though, so I have to agree that exhaust improvements and intake improvements would help out. The cam is a good move as long as your intake and exhaust is up to it. You don't want to go for a huge cam if you have stock intake, heads, and single exhaust. I agree with the thought that underdrive pulleys and the expensive filters will not give you much bang for the buck.

AC

robzr

The guy with the heads's email is: kbud1@bellsouth.net

Rob

Ganey

Yes, Ex. is first. For HP on 75-81, see what many refer to as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm

Next is cam ! Then heads.

:cool:

bud snyder

szercer,
Ganey is 100% correct! Cam first then Heads. A better flowing set of heads with a Cam that doesn't have the duration to supply them will not reap the full potential of the heads.
If you change the Cam, choose wisely! The cam you choose will definetly be the most deciding factor determing your overall potential. It seems that the Comp. 262 & 268 XEs are the flat tappet cams of choice on the Forum. (I personally run the 274, and I think it is about the max. for a street car and don't look for gas milage). If you are like me and can not perform the change yourself, it is somewhat expense. ($850.00). If you install a new intake at the same time, you save that labor cost Vs. installing later.
If you chose to use the Vortac heads, the intake issue is only a small price increase. (As a matter of Fact, I have a 2116 Edelbrock Performer for sale). under 76 hood. Valve covers are cheap and if you buy headers, get the new design from Hedman.
You need to take your time and evaluate what you want as the end result!
If you do and match your new perform parts to each other it will MAXIMIZE your investment the FIRST time.
Good Luck,
Bud
Ps. I use a 14" drop base and the top of the cleaner housing is soo close to the hood insulation that the air cleaner top that you mentioned would be of little benefit.

Sorry Ganey,
The posts are long and the memory is short. I agree with you though that the exhaust is important! I just got a little side tracked.



[Modified by bud snyder, 11:30 AM 3/23/2002]