L48 enhancement
Thread Starter
Intermediate
Joined: Jan 2005
Posts: 32
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From: Hurst TX
L48 enhancement
I have a 74 L-48 with 70,000 miles on the odometer , I am going to be replacing the radiator and thought this might me a good time to install a better cam. I would like a little better performance. How much HP might I gain by installing a better cam and what cam would be advisable. I would like to avoid any other engine work at this time unless necessary. Will this work? 
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
I don't know exactly how many HP you would gain, but I think it would NOT be enough to justify the disassembly/reassembly of your engine [without doing other "good" things to it]. I'm guessing it would be in the 15-25hp range, and with the L-48 engine's original power level...and with 70K miles on it....it probably won't perform as you would hope.
Change the radiator (if it is damaged), or give it a good cleaning [not just a flush], and get back to enjoying it. When you research what you really want for an engine upgrade, plan it thoroughly, then do it!
Change the radiator (if it is damaged), or give it a good cleaning [not just a flush], and get back to enjoying it. When you research what you really want for an engine upgrade, plan it thoroughly, then do it!
Race Director
Joined: Sep 2001
Posts: 10,560
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From: Wellington, FL
St. Jude Donor '11 thru '25
Originally Posted by 7T1vette
I don't know exactly how many HP you would gain, but I think it would NOT be enough to justify the disassembly/reassembly of your engine [without doing other "good" things to it]. I'm guessing it would be in the 15-25hp range, and with the L-48 engine's original power level...and with 70K miles on it....it probably won't perform as you would hope.
Change the radiator (if it is damaged), or give it a good cleaning [not just a flush], and get back to enjoying it. When you research what you really want for an engine upgrade, plan it thoroughly, then do it!
Change the radiator (if it is damaged), or give it a good cleaning [not just a flush], and get back to enjoying it. When you research what you really want for an engine upgrade, plan it thoroughly, then do it!
Spending money on such upgrades on an engine of this vintage is a waste of time and effort. Vettes produced around this time had the least hp of any.
Pro
Joined: Oct 2006
Posts: 545
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From: Peoplez Republik (communist portland) Orygun
Originally Posted by 7T1vette
it would NOT be enough to justify the disassembly/reassembly of your engine [without doing other "good" things to it]. ...it probably won't perform as you would hope.
Yep, just changing the cam isn't going to boost all that much, maybe just make it even harder to tune. IMO.
If it were just a "one item" to increase performance, I'd put in 1&5/8 fullbore long tube headers. At $150 it would be the single most easy/inexpensive mod to do.
But, others just may tell you otherwise....
Melting Slicks
Joined: Mar 2006
Posts: 3,342
Likes: 7
From: Connecticut
Originally Posted by Jud Chapin
Spending money on such upgrades on an engine of this vintage is a waste of time and effort. Vettes produced around this time had the least hp of any.I recently did a top end upgrade on a my '73 L-48 and the results are very good
The engine is much stronger and pulls very well.
In my case the bottom end was in very good shape as it has very low miles on it.
The only major drawback are the stock dished pistons but you can still achieve compression in the mid 9's with the proper heads and gaskets.
It can be done for about 1,000 to $1,500 and I believe it's well worth it.
Le Mans Master
Joined: Oct 2004
Posts: 5,269
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From: Orlando Florida
St. Jude Donor '05
have to agree with Bob here, the L48 responds well to a better cam. Well... it's difficult to find a cam that is worse than the stock L48 cam 
it would make a lot more sense to upgrade heads/exhaust/intake as well but the cam itself - if you have the radiator out of the way anyways - is a good idea
look at the Summit 1103 - that's a decent cam for the money and way better than what you have now
it's not going to be a 50HP gain but worth the money
it would make a lot more sense to upgrade heads/exhaust/intake as well but the cam itself - if you have the radiator out of the way anyways - is a good idea
look at the Summit 1103 - that's a decent cam for the money and way better than what you have now
it's not going to be a 50HP gain but worth the money
Safety Car
Joined: Dec 2004
Posts: 4,071
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From: San Diego CA
I upgraded the cam in my '81, which went flat, to the summit 1103 and I was greatly impressed by how much more power I had afterwards. You can get the cam and lifter kit from summit for like $60 or $80, well worth it in my opinion.
I would say go with maybe the 1104, though, if you have or are going to get open exhaust.
Race Director
Joined: Sep 2001
Posts: 10,560
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From: Wellington, FL
St. Jude Donor '11 thru '25
Well, I guess my point is that if you are going to spend money on up- grading one of these engines of the low hp years, I think the $ would be better spent looking at a new engine and be done with it. Just my 2 cents.
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Race Director
Joined: Apr 1999
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From: CORVETTE 77 385 C.I. TEXAS
As practically everyone into Chevy performance knows many fast cars have been built starting with a standard Chevy V8.
The cam can be thought of as the engine's mechanical "program". A dramatic day & night difference can be made.
When the cam is changed, that is a good time to change the intake.
It is possible to increase 50 HP.
You need to state at least trans. for cam. If you know rear gears that would be good to state. What about mufflers & maybe headers later?
The cam can be thought of as the engine's mechanical "program". A dramatic day & night difference can be made.
When the cam is changed, that is a good time to change the intake.
It is possible to increase 50 HP.
You need to state at least trans. for cam. If you know rear gears that would be good to state. What about mufflers & maybe headers later?
