L48 Top End Upgrades vs. 383 Stroker
08-01-2011, 07:44 PM
#1
6th Gear
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L48 Top End Upgrades vs. 383 Stroker
I inherited my grandfathers '79 L48 stock 350 and am working to learn about my options for what I want to do with it.
I've heard that the L48 motor was not the best motor Chevy designed as far as compression and overall power goes. I don't really want to invest the money to swap the motor entirely but I do want to spend some money, just not sure what to do. So I turn to the experts...
Should I have the work done to make it a 383 Stroker or just upgrade the top end of the existing setup with new carb, cam, intake manifold etc. Is the power gained from doing the full 383 conversion worth the added cost of the machining/crank etc? I'd do all the top end stuff anyway so I guess the question is how much more will it cost to do the full 383ci conversion..?
The only thing I've done so far is install Hooker headers and side pipes (bc they're sexy as all hell on C3's) and have on order the Spiral Baffle inserts.
The engine and transmission were re-built only 5-6K miles ago so says my grandfather. I have the receipts to prove that he spent over 7K on the motor, but he kept it entirely stock. So now it's up to me and what I want to do with it while staying within reasonable cost controls.
Your thoughts? I've read some other threads on similar topics. What I want to do is increase the performance as much as I can without doing a complete engine swap so want your opinions on upgrading to the 383 vs only doing top end?
I've heard that the L48 motor was not the best motor Chevy designed as far as compression and overall power goes. I don't really want to invest the money to swap the motor entirely but I do want to spend some money, just not sure what to do. So I turn to the experts...
Should I have the work done to make it a 383 Stroker or just upgrade the top end of the existing setup with new carb, cam, intake manifold etc. Is the power gained from doing the full 383 conversion worth the added cost of the machining/crank etc? I'd do all the top end stuff anyway so I guess the question is how much more will it cost to do the full 383ci conversion..?
The only thing I've done so far is install Hooker headers and side pipes (bc they're sexy as all hell on C3's) and have on order the Spiral Baffle inserts.
The engine and transmission were re-built only 5-6K miles ago so says my grandfather. I have the receipts to prove that he spent over 7K on the motor, but he kept it entirely stock. So now it's up to me and what I want to do with it while staying within reasonable cost controls.
Your thoughts? I've read some other threads on similar topics. What I want to do is increase the performance as much as I can without doing a complete engine swap so want your opinions on upgrading to the 383 vs only doing top end?
08-01-2011, 08:24 PM
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Race Director
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...
The engine and transmission were re-built only 5-6K miles ago so says my grandfather. I have the receipts to prove that he spent over 7K on the motor, but he kept it entirely stock. So now it's up to me and what I want to do with it while staying within reasonable cost controls.
Your thoughts?
The engine and transmission were re-built only 5-6K miles ago so says my grandfather. I have the receipts to prove that he spent over 7K on the motor, but he kept it entirely stock. So now it's up to me and what I want to do with it while staying within reasonable cost controls.
Your thoughts?
08-01-2011, 09:28 PM
#3
Race Director
I think you took the easiest and most cost effective first step by upgrading the exhaust. That's a huge choke point gone. Unfortunately, I think your next big choke point are the heads. I don't think you'll realize huge gains with an intake and cam with those old heads on there.
Make sure that your timing is optimized. You'll be surprised how much difference that can make. Look up the timing curve paper by Lars Grimsrud at corrvettefaq.com.
Make sure that your timing is optimized. You'll be surprised how much difference that can make. Look up the timing curve paper by Lars Grimsrud at corrvettefaq.com.
08-01-2011, 11:27 PM
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Le Mans Master
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The easiest way to do it may be to look into one of those top end kits, from places like Edelbrock, Twisted Flow, Summit Racing, etc., . You could probably do the whole thing in a long weekend, if you had a few friends who knew what they were doing helping out.
Scott
Scott
08-01-2011, 11:57 PM
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St. Jude Donor '05
Ive never been happy with any H/C upgrade on a 350 (trust me Ive done them all) you never get the power you think you will
Go for the larger motor youll be so much happier take that one to the bank
Difference is a few hundred maybe for torque you will notice everywhere!
Go for the larger motor youll be so much happier take that one to the bank
Difference is a few hundred maybe for torque you will notice everywhere!
08-02-2011, 12:51 AM
#7
Le Mans Master
Budget is the big question here - but with a fresh rebuild I wouldn't start over with a 383.
Heads, cam and intake...all determined by your budget
Heads, cam and intake...all determined by your budget
08-02-2011, 04:36 PM
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Thanks for all the comments. I think the most rational decision is to keep the motor and build the top end. I'm only 25 so I have plenty of years to contemplate and save for a complete engine swap down the road when I've had my fun with the 350! 
08-03-2011, 08:00 AM
#9
Drifting
Heads,cam,and intake would be my choice.IF you want to go cheap get some vortec heads,intake,and a 600/650 carb,Recurve the distributor with an advance kit to get the timing in sooner and rock and roll.
The smaller combustion chambers will up the compression(plus the are more efficient promoting better combustion)which helps power everywhere.
Even the entry level alum heads from Jegs/Summit would suit a mild build well.We recently put a set on a freshened 350 with a cam,headers,intake and 4bbl and it made quite a difference.Even held up to the 125 shot we put on it.
The old trick flow twisted wedge heads were a great bolt on increase for me anyway.
Keep the cam mild(like a comp XE 262-268 or similar) and it will all work together to make good low end and midrange with top end to keep you happy,AND it will be dead nuts reliable.
Also if you get a top end now it can be switched to a 383 shortblock later.It may be top end limited due to the size of the runners in the heads but still a torque monster.
The smaller combustion chambers will up the compression(plus the are more efficient promoting better combustion)which helps power everywhere.
Even the entry level alum heads from Jegs/Summit would suit a mild build well.We recently put a set on a freshened 350 with a cam,headers,intake and 4bbl and it made quite a difference.Even held up to the 125 shot we put on it.
The old trick flow twisted wedge heads were a great bolt on increase for me anyway.
Keep the cam mild(like a comp XE 262-268 or similar) and it will all work together to make good low end and midrange with top end to keep you happy,AND it will be dead nuts reliable.
Also if you get a top end now it can be switched to a 383 shortblock later.It may be top end limited due to the size of the runners in the heads but still a torque monster.
