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  1. #1
    Member krscholz's Avatar
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    Default High Performance Heads vs L82 Heads Strapped on an L48 - Quest for more Horsepower!

    I have a 75 L48 and don't rub it in about the horsepower. In my quest to improve performance I'm looking into finding a pair of L82 heads in a wrecking yard vs going with an aftermarket high performance set. Yes, I know I need to change the cam as well to do this job. Also, the pistons are differnent in the L82. I'm trying to save some money here if you can hear my concern and I was thinking the L82 heads would be a less expensive route to get my wimpy horsepower up. If I go the wrecking yard route, I was thinking about trying first to see if I can a set of heads from a 73 Camaro Z-28. I have an exchange cataolgue that points me to the right production number. The reason for this year is that this was the highest horsepower year for L82s'. My question is would a later year work just as well?

  2. #2
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    L82s all used the same cylinder had so any year L82 head would work.

  3. #3
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    In some years both L48 and L82 used the same casting number heads, so don't presume you've got the L82 versions unless you can measure the valve diameters.

    Unless you can bump up compression significantly a cam and head change won't do much any way.

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    Member krscholz's Avatar
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    That is what I thought because the application seems to be the same regardless of what year. I will check the valves first to be sure.

  5. #5
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    L82 heads used 1.94" intake valves.
    Hib Halverson

  6. #6
    Moderator KANE's Avatar
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    Quote Originally Posted by Vettehead Mikey View Post
    Unless you can bump up compression significantly a cam and head change won't do much any way.
    I agree with Mikey.

    Besides- the L82s weren't the best flowing heads and in many cases- the castings were thin (my old L82 fell victim to thin castings and a bad valve ).

    True- you could get the L82s ported... but that costs money... money that could be sunk into a set of Vortec heads and a Vortec intake- and swap the cam out while I was there. Or even install a set of 1.6 roller tip rockers in the interim for a little more lift until I had the money for a cam swap.

    Personally- I'd save the headaches and go with a complete set of assembled cast iron Vortecs. Dollar for dollar- the Vortecs are pretty good.

  7. #7
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    I had a 76 L48 car last month for a week. it had (I don't know what kind) heads and what seemed to be a solid lifter cam with a pretty good rock to it. Even with that stuff, it was mighty slow. Without raising the compression I don't think it's going to do you much good. The car did sound cool though.
    The best sound my L48 ever made was when it hit the garage floor!

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    If you are going the wrecking yard route,try to grab some aluminum heads off a L98 C4 Corvette with the 58cc chambers. Just remember you will pay more in machine work on any used head than just buying a new set of Vortecs.

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    Heads with 58cc chambers on an engine with pistons designed for 76cc chambers?

    Uh...don't you think that might have the compression ratio a wee bit high for pump gas?

  10. #10
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    Just a thought since money is always an issue for most of us. 80-86 Corvette/Camero 305 heads with the 184 /150 valves and small cambers can work. You still need to port the intake & exhuast. They have 58cc cambers and once ported they flow better than the stock 350 heads. Don't mistake the standard 172 305 heads; they wouldn't do the job.

    Just something to think about.

    Gary

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    Member Bronze85's Avatar
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    Quote Originally Posted by Hib Halverson View Post
    Heads with 58cc chambers on an engine with pistons designed for 76cc chambers?

    Uh...don't you think that might have the compression ratio a wee bit high for pump gas?
    Would'nt a cam with more duration bleed off some compression? Also, I've been told aluminum heads require a higher comp. ratio.

  12. #12
    Member 73shark's Avatar
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    The LT-1 11:1 CR pistons w/ the L-82 heads will yield about 10:1 CR according to the TRW book.

    My L-82 heads have 2.02 intake valves.
    Save the wave

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    The L-82 heads are indeed 2.02/1.60. I just listed a pair for sale along with some other stuff. Let me know if you are interested. They are definately an upgrade from the L-48's! I went with new Edelbrock RPM (to match my intake and cam) and increased the flow numbers with addition work-about a $1400.00 investment. You can get the L-82 heads and a valve job and end up at about $400.00.

  14. #14
    Member Jack's Avatar
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    Default dish OE L48 + GM 10105117 gasket + L98 aka ZZ4 head yields ~ 9 3/4:1 scr

    Quote Originally Posted by krscholz View Post
    I have a 75 L48 and don't rub it in about the horsepower. In my quest to improve performance I'm looking into finding a pair of L82 heads in a wrecking yard vs going with an aftermarket high performance set. Yes, I know I need to change the cam as well to do this job. Also, the pistons are differnent in the L82. I'm trying to save some money here if you can hear my concern and I was thinking the L82 heads would be a less expensive route to get my wimpy horsepower up. If I go the wrecking yard route, I was thinking about trying first to see if I can a set of heads from a 73 Camaro Z-28. I have an exchange cataolgue that points me to the right production number. The reason for this year is that this was the highest horsepower year for L82s'. My question is would a later year work just as well?
    No significant performance difference L48 v. L82 heads. Both have 76cc chamber & same size ports-runners. L48 needs lots more compression & more cam. '75-up needs true dual exhaust.

    Quote Originally Posted by sharkcar71 View Post
    If you are going the wrecking yard route,try to grab some aluminum heads off a L98 C4 Corvette with the 58cc chambers.....


    Quote Originally Posted by Hib Halverson View Post
    Heads with 58cc chambers on an engine with pistons designed for 76cc chambers?

    Uh...don't you think that might have the compression ratio a wee bit high for pump gas?
    I've no doubt resulting CR will be OK with pump gas & alum heads.
    OP has L48 ... OE L48 has dished pistons ... that's a good candidate for GM L98 aka ZZ4 heads (alum 58cc).

    dish OE L48 in combo w/ GM 10105117 head gasket (about 5.8cc) & 58cc chambers will yield about 9 3/4:1 static compression.

    FYI ... owing to L98-ZZ4 head's high efficiency exhaust port, a single-pattern cam is probably best.

    Merry Christmas y'all

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