1976 L-48 upgrade question
Thread Starter
Drifting
Joined: Aug 2007
Posts: 1,838
Likes: 13
From: Kingman AZ
1976 L-48 upgrade question
I have an L-48 with 63K original well cared for motor. Never beat. Don't want to do the bottom end. What are the thoughts on something in a package like Edelbrock's 2098 kit. It has a matched cam heads roller.. .other goodies. Says it will be 410 hp. 10.5 comp. So even if its 375 Im ok with it, Im wondering if I dont beat on the motor and use it mildly aggressive on occasion . is this a good idea?
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
most kits that say 10:1 or more ASSUME you begin with flattop pistons ... L48 has Dished pistons with much lower compression than if flattop.
Less compression equals less power and a cam speced for higher compression will usually make a lower comp motor act like a slug.
Less compression equals less power and a cam speced for higher compression will usually make a lower comp motor act like a slug.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
You dont have enought compression. That said go aftermakret the GM stuff back then was bad. Heads cams all of it.
Start over...lol There are some that worhsip 60s & 70s parts. If you want performance ignore 100 percent of it.
Start over...lol There are some that worhsip 60s & 70s parts. If you want performance ignore 100 percent of it.
Last edited by cv67; Nov 15, 2019 at 05:05 AM.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
I have an L-48 with 63K original well cared for motor. Never beat. Don't want to do the bottom end. What are the thoughts on something in a package like Edelbrock's 2098 kit. It has a matched cam heads roller.. .other goodies. Says it will be 410 hp. 10.5 comp. So even if its 375 Im ok with it, Im wondering if I dont beat on the motor and use it mildly aggressive on occasion . is this a good idea?
use GM small chamber (58cc) L98 aka ZZ4 aluminum heads ... they're no longer in production and have limited availability ... OR ...
at about $1300-$1400 per pair ... TFS 60cc alum heads https://www.summitracing.com/parts/t...0006/overview/ ... these flow better than L98 and have greater potential
OE L98 heads, OE L48 pistons, OE decks with shim head gaskets will make about 10.1:1 static compression ... OR ...
TFS 60cc heads, OE L48 pistons, OE decks with shim head gaskets will make about 9.9:1 static compression
From there, then choose a cam ... there're thousands ... you can reliably & easily make 330-400hp
Race Director
Joined: Mar 2016
Posts: 14,406
Likes: 8,212
From: Napa Valley California
Are you going to change your style of driving?
It doesn't sound like it.
If you are looking for a few extra hp/torque I would look at a set of good headers, and exhaust system, swap out your intake, and either have LARS rebuild your OEM carb or replace it.
Look at your style of driving and figure out where you want or need the additional hp/torque and find a roller camshaft that is going to increase the power where you want and need it.
If you want to find a good set of heads, look at all the manufactures and find the heads that will work best for your desired performance gains.
Everything has to work together and it all has to perform where you want the increase in hp/torque to be.
Installing a high lift cam and large port, high flowing heads might be just what you would want if you plan to run your engine at 5000 to 7000 rpm, but if you want to make better low end or mid-range hp/torque you need to design all the components to work together in the rpm range you want to see improvement.
It doesn't sound like it.
If you are looking for a few extra hp/torque I would look at a set of good headers, and exhaust system, swap out your intake, and either have LARS rebuild your OEM carb or replace it.
Look at your style of driving and figure out where you want or need the additional hp/torque and find a roller camshaft that is going to increase the power where you want and need it.
If you want to find a good set of heads, look at all the manufactures and find the heads that will work best for your desired performance gains.
Everything has to work together and it all has to perform where you want the increase in hp/torque to be.
Installing a high lift cam and large port, high flowing heads might be just what you would want if you plan to run your engine at 5000 to 7000 rpm, but if you want to make better low end or mid-range hp/torque you need to design all the components to work together in the rpm range you want to see improvement.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
FWIW ... summit's house brand of cams ... has cam & lifters that're essentially same as what's in edelbrock's 2098 kit ... sum-K1107 ... for $112
https://www.summitracing.com/parts/s...make/chevrolet
Not saying that the best choice ... although it's a close comparison
https://www.summitracing.com/parts/s...make/chevrolet
Not saying that the best choice ... although it's a close comparison
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
L-98 heads have horrible ports intake and exhaust, and porting them does very little.....the increase in compression is not worth it. These heads were all the rage 25 years ago and now we are 25 years on.
The Trick Flow option is a good one.....60cc chamber. A Dart 180 64cc chamber will put you in the mid 9's for compression....and it is a stellar street head for 350's.
Team it with Dart's Air Gap intake.....a Comp 268H cam...long tube headers and a 670 Holley Truck Avenger carb......I have built this combo and it is stupid fun for a 350.
The L-48 pistons are crap but they will work......don't get too hung up on it.....
Don't forget an MSD distributor with the proper curve.
Jebby
The Trick Flow option is a good one.....60cc chamber. A Dart 180 64cc chamber will put you in the mid 9's for compression....and it is a stellar street head for 350's.
Team it with Dart's Air Gap intake.....a Comp 268H cam...long tube headers and a 670 Holley Truck Avenger carb......I have built this combo and it is stupid fun for a 350.
The L-48 pistons are crap but they will work......don't get too hung up on it.....
Don't forget an MSD distributor with the proper curve.
Jebby
Last edited by Jebbysan; Nov 15, 2019 at 01:07 PM.
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Burning Brakes
Joined: Dec 2017
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2023 C3 of the Year Finalist - Modified
Just my opinion. I also have an L48. I also wanted more power without rebuilding the bottom end. I bought an edelbrock top end kit. I wouldn’t recommend it without just going ahead and rebuilding the whole engine. What happened to me was I think either the bigger cam or during my removal and install of the cam, I damaged my cam bearings. The damaged bearings sent metal all through my engine and within 500 miles it was knocking. Had to pull the engine out and rebuild it, which is what I should have done in the first place. Runs fantastic now.
But yeah, top end swap without doing the bottom end did not work our for me.
But yeah, top end swap without doing the bottom end did not work our for me.
