L48 chevy 350/300hp
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2nd Gear
Joined: Jan 2017
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L48 chevy 350/300hp
I just purchased a 1970 350 l48 with 014 block and 041 heads, just finished the tear down and the cam and lifters are bad. I do not want to build a stroker 383 I just want to rebuild this engine with minimal upgrades and wanted to know if anyone here has been successful in gaining any additional horsepower with just upgrading the cam and going to a solid lifter and roller rockers and converting to HEI distributor and electronic fuel pump. And if so what parts did you use and what kinds of results did you get.
Melting Slicks
Joined: May 2012
Posts: 2,192
Likes: 343
From: Allenton Wisconsin
Heads and cam is were you get your power. There are electronic ignition kits available that you can install yourself and still retain your tach drive dist. Holley makes excellent mechanical fuel pumps. L48 300 hp engines have 1.94 diameter intake valves, you need better breathing heads to go any further. DART has good iron heads priced reasonably and after that call some cam manufactures, tell them your goals and get their opinion. You don't need solid lifters, they need readjustment frequently and are really only needed for higher RPM. A good hydraulic cam is all you need unless you want the clacking noise of solids. I like your idea of roller rockers. Do some research, make some calls and see what you like. I know from experience the L48 is a dog, but a vette with 350 to 375hp is a blast to drive. Welcome to the club, there are a lot of members here that will give you excellent advice. After you made some choices add them to your post and see what the members think. T
PS; Are you going to get the block boiled out and replace the bearings and oil pump?
PS; Are you going to get the block boiled out and replace the bearings and oil pump?
Drifting
Joined: Oct 2005
Posts: 1,615
Likes: 150
From: Forth Worth TX
A 1970 350/300hp (base engine) has a poor flowing cast iron intake manifold and poor flowing heads with small valves.
A cam and HEI distributor will not make any significant gains on their own. Probably less than 10hp or 15hp.
You don't really need an HEI or electric fuel pump either. What's in the car will function just fine for most street driven higher HP applications.
If you are looking for a 50hp+ gain, you will need to change the intake manifold and heads as well.
I would either rebuild back to stock or plan on a new intake manifold, new heads and new cam. The original block, crank and pistons should be fine for a 400hp engine.
A cam and HEI distributor will not make any significant gains on their own. Probably less than 10hp or 15hp.
You don't really need an HEI or electric fuel pump either. What's in the car will function just fine for most street driven higher HP applications.
If you are looking for a 50hp+ gain, you will need to change the intake manifold and heads as well.
I would either rebuild back to stock or plan on a new intake manifold, new heads and new cam. The original block, crank and pistons should be fine for a 400hp engine.
Last edited by Revi; Jan 30, 2017 at 08:09 AM.
Burning Brakes
Joined: Feb 2005
Posts: 894
Likes: 91
I just purchased a 1970 350 l48 with 014 block and 041 heads, just finished the tear down and the cam and lifters are bad. I do not want to build a stroker 383 I just want to rebuild this engine with minimal upgrades and wanted to know if anyone here has been successful in gaining any additional horsepower with just upgrading the cam and going to a solid lifter and roller rockers and converting to HEI distributor and electronic fuel pump. And if so what parts did you use and what kinds of results did you get.
That fact aside, going the retro-hyd roller platform will yield an add'l 30 (nominal) HP by design with either the 350" or the 383".
More than 90% of our 100% stock-appearing builds now get the full roller platform. Using the correct pieces keeps the "look", right down to the single-thick valve cover gaskets!
Thanks, Gary in N.Y.
P.S. On all our roller builds (on the early SBC platform) we no longer find it necessary to check/set cam end-play OR use cam-buttons anymore! We modify the blocks to use the later stepped-nose cams and a retainer plate. Cam end-play is "fixed" using this new method, nothing touches inside the (stock) timing covers any longer.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
member here is selling some low mile Edelbrock E street heads for about $600 plenty better than what you have
Grab those, a used performer or rpm (he has one too)intake go grab a modest solid flat tappet and make some power. Dont forget to recurve the distributor, rejet and stick soe headers on. Should be plenty of fun. Love the sounds of a solid and the way they run!
Think youll easily exceed your goal here and be plenty driveable
Grab those, a used performer or rpm (he has one too)intake go grab a modest solid flat tappet and make some power. Dont forget to recurve the distributor, rejet and stick soe headers on. Should be plenty of fun. Love the sounds of a solid and the way they run!
Think youll easily exceed your goal here and be plenty driveable
Last edited by cv67; Jan 30, 2017 at 06:19 PM.
Thread Starter
2nd Gear
Joined: Jan 2017
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Thank you
So much to think about, so many possibilities. Was about to take the block and heads to a machine shop but I am definitely going to do some more research, thinking 383 May be the way to go to get the look and the power I want. Thank you all for your advice, greatly appreciate it
