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Thread: 1976 l65 350 questions

  1. #1
    Senior Member EXPERT BUILDER
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    1976 l65 350 questions

    can anyone tell me the stock specs on this engine like compression ratio stock and what type of heads they had on them cast# or valve size and combustion chamber cc would help me out a great deal
    any help i would appreciate
    thanks Logan

  2. #2
    Senior Member RACING JUNKIE
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    wasnt 1974 the last year for that motor?
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  3. #3
    Senior Member RACING JUNKIE
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    The 1974 L65 (350 2-barrel) and the 1978 LM1 (350 4-barrel) were almost entirely the same engine. The cam was the same, the heads were the same (1.94" intake, 1.50" exhaust). The block was the same 2-bolt main, cast crank affair. Chevy began putting hardend valve seats starting with the '73s, along with the EGR valve. Aside from the intake manifold differences (2 barrel vs. 4-barrel) I think the choke pull-off was different. Starting with the 75s Chevy went with the HEI big cap distributors (integrated coil starting in '78), plus the catalytic converter was used. This allowed the engineers to retune the carb and timing for better running since the catalytic converter would clean up a lot downstream.
    One difference between the two versions of the 350, and one I found a bit surprising, was the compression. From 1971 through 1976 the 350 had an 8.5:1 compression, but it was dropped to 8.25:1 for '77.
    The cam was the very common general performance cam that was used in 307s, some 327s, most 350s and the 400. The cam timing was 280 degree intake, 288 degree exhaust, 58 degree overlap, .410" lift.

    Horsepower in '74 was 145 net for the 2-barrel, 160 net for the California LM1 4-barrel single exhaust, 185 net for the L48 4-barrel dual exhaust (Canadian Chevelles only for '74). Torque was 250 net lbs./ft. @ 2200 rpm (L65), 250 lbs./ft. @ 2400 rpm (LM1), 270 lbs./ft. @ 2600 rpm (L48).
    Horsepower for the LM1 in '78 was 170 on regular Camaros (160 California) or 185 for the Z28 (175 Calf.). The only difference between the base Camaro & Z28 was the use of the low restriction exhaust on the Z28 (2.25 & 2.5" pipes, no mufflers but twin resonators). Torque went from a low of 260 net lbs./ft. @ 2400 rpm on non Z28 California cars to 280 @ 2400 on the 49 state (& Canada)Z28.
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  4. #4
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    thanks for the info was the 8.5:1 with 76 cc heads , 64cc heads , or 58 cc heads
    thanks logan

  5. #5
    Senior Member RACING JUNKIE
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    here is a few good guides for looking up head numbers

    http://www.fastnuf.com/Headguide.html

    http://www.thedirtforum.com/castings.htm
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  6. #6
    Senior Member RACING JUNKIE
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    74 was first year for hei personaly unless going for 100% perfect restore dump the small valve heads and go with a thin head gasket then small valves choke the chit out of the motor
    CRIMEDOG
    Sam Wood

  7. #7
    Member CRAFTSMAN
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    76 cc heads I beleave, 64 cc heads should get you about 9.25 to one.
    This wouldn't have happened if only you had been paying attention!

  8. #8
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    alright thanks for the info i was hopeful it was 76 cc so i could get a little more compression out of it and better flow than the 1.7? intake and 1.5 exhaust that were on it
    thanks and if anyone has ant tip to get me more horse power out of it with a stock bottom end different heads and 292/292 488/488 cam i would appreciate it
    thanks logan


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