vicrattlehead

I want to start gently increasing the output of my stock L-48. I've read that installing higher-than-stock ratio rocker arms can fool the motor into thinking it has a bigger cam. Is this swap a wise first step in modifying the motor or is it a dangerous waste of time? Any academic guesses as to the net effect of this change? I'm also thinking of adding a better flowing intake, should I tackle this before playing with the valve train? :rolleyes:

Ganey

The gain would be minimal. L-48 badly needs more cam which could be done at same time as intake. That would wake it up.
See if the ex. is stock single. See Why Exhaust is problem for HP on 75-81 , what many refer to as my Exhaust topic. http://www.corvettefaq.com/c3/ganeyexhaust.htm

vicrattlehead

Thanks for mentioning that. I should have noted that the last owner of my 79 installed true dual stainless exhaust, no cats (if you work for the Illinois DMV, you didn't read that), and there is no AIR pump installed (again if you work for the....). I also recently installed an Accel Super Stock Coil. Other than that stuff, the motor is stock. Thanks!

AlwaysWave

I used the Comp Cams roller tip 1.6 rockers. The gain may be minimal but I felt it.

Ganey

For a stock L-48 auto./converter/gears w/o rebuild, you would probably be happiest w/ HE 260H which works w/ stock valve springs or XE256 w/ new valve springs. This gives more low rpm HP/TQ to get you off the line & only about 20 less hp at high rpm than 1 more step up on the cam.

Justin79-L-82

Roller rockers will only increase power significantly if you have a well built motor that spends alot of time at high rmps, other wise they are a waste of money as far as i'm concerned.

mxzx turbine

sorry, have to disagree, true roller rockers, reduce drag in the valve train significantly, they also contribute to lower oil temp by reducing friction associated with upper valve train components which inturn reduces the amount energy wasted as heat in the engine and transfered to the oil. as heat and oil contamination are an engines worst enemy roller rockers are a good investment,

My .02

:party:

vicrattlehead

This is very interesting stuff. So it sounds like roller rockers definitely can't hurt, but getting back to my original question, would I gain anything with the higher ratio in terms of power in addition to the lower oil temp. issue? It sounds like the increase will be minimal, but that's fine with me, I want to enter the engine slowly one area at a time instead of just tearing everything down. I just don't have the time or money to do everything at once. :nonod:

WillRace4Food

You will feel a difference with the true roller rocker and the addition in lift. What are the stock stamped rocker ratio. 1.45?. An increase to 1.6 would in effect give you more cam. Not the best way to increase power but it does work and is fairly simple. I've seen dyno results on a stock LT1(f-body) car gain 11 rwhp with the change.

Tim

Chris O'

If you are changing the intake - change the cam at the same time! Saves drama's and is probably cheaper that a set of rockers. You'll gain a lot more than 11 hp too!

:cheers:

vicrattlehead

I think the stock stamped rocker arms are 1.50. I'm making an assumption on this since the aftermarket companies (like Crane Cams) say their "stock" replacement rocker arms are 1.50. They sell the high ratios as 1.60. More than anything this modification would be a worthwhile reason for me to go in and learn how to work on the valvetrain and get to know my engine better. I'm thinking more and more about adding an intake at the same time though. I would also do the cam, but pulling the radiator and the like really scares me (maybe I'm just packin' a 'giner though).

Aaron-74

Going to 1.6 rockers may cause..MAY..cause the pushrods to rub the push rod slots in the heads. I had to drill mine out on my 882 heads.


Taking out the radiator is not that hard to do. Butt, i don't have A/C so that helps a little bit. There's no better change to make than a good cam, good exhaust and maybe a gear change IMO..

-Aaron

tnt76vette

My $.02: Heed Ganey's words. I did about 3 yrs ago and have been :D ever since......My low end mild CompCam 260H made a big difference in all Rpm's but esp the low end, which is where you want it for a Street motor. There are many directions to go, but what you really NEED now is a good low end cam.....Trust me on this one. :cheers: PS: See my Signature as to what I have done. Heads were the last mod made just this winter. DD's 345 HP & 409 ft/lbs of torque

WillRace4Food

Its a good place to start. Put a good manafold on it too and you will feel a noticable difference in power. Do headers/exhaust too if your feeling squirly. Do the "breathing" mods first if your leary about going into your motor. When I had my stock l-48 my cam flattened a lobe. The guy who replaced it got the l-82 cam and stuck it in. There was a nice change in power if I remember right(about 13 years ago). After that I did headers and it picked up again.

page62

I'm gonna go totally off track here. The cheapest (and best) bang for your buck is a Lars recurve kit. I installed one of these a few weeks ago and all I can say is WOW!

You can do a lot more (and better) things with the money you'd otherwise be spending on rockers. Like saving up for an OD tranny :yesnod:

Glensgages

You say you're gonna make small increases as you go? The roller-tip, high-ratio rockers will work with most ANY future modification. (Realize that when you go cam-shopping in the future, you'll be looking at lifts figured @ 1.5:1 ratios, but you'll have 1.6 ratio rockers...) My thinking is this; work BACKWARDS! Figure out what your 'final' combination will be, and add the pieces that'll work in the combination as time & finances afford. If you're gonna end-up with a 292H cam, you may not wanna bother with the 260H in the 'short term'. Install all the 'small' pieces that'll work in the 'final' set-up as you go; they'll all work when you go 'whole-hog'.... Just my $.02 worth.... :chevy

7T9Shark

The head number you posted. I am interested in that. What is the rest of the number, and what year are they off of? Sounds like the route I want to take to warm up my '79?

Thnx

Vetterodder

As others have said, going to the 1.6 rockers will give you a slight improvement. If you're talking about a $90 set of stamped steel 1.6's, the bang for your bucks (small bang but small bucks also) won't be bad. If you want the most power for the money out of an L48 though, nothing will beat a better cam. Spending $90 for maybe 9hp isn't bad but spending $200-300 for 40-50hp is much better. Yes it's more work but, if you can turn one bolt, you can turn a bunch of them :)

Crash Dummy

How did this end up with *roller rockers*? Roller rockers go with roller lifters & work with roller cams. Any low compression... low horsepower engine does not need *roller* anything in it. That's like buying a 2.4G Pentium 4 processor and expecting to surf the internet faster with a 33K modem. Granted... it should be an efficient 33k. Stupid.... but, efficient! :thumbs:

BacaBill

I also have a '79, originally a L82, but it's been replaced with a GM crate engine part # 10067353, supposedly 249hp outta the box. Anyone have any idea of what cam is in this now? I don't wanna buy the same cam that's already in there. Also installed, w/ the engine change, is an Edelbrock Performer intake w/ a Edelbrock 750 double pump # 1411. What's the best cam to get the best low-mid rpm torque? I don't have headers yet, but they won't be far behind either.
Thanx alot,
Bill