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  1. #1
    Jimmy C

    Default Intake/Exhaust Valve Size?

    I have an '81 Corvette, all original. It still runs great and the engine has never been internally touched. Being tired of the car just looking good and not running like a 'Vette should (IMO), I'm going to do some engine work and give it some guts. I've been looking into buying a set of heads, but want to know exactly what I've got in the stock engine and if the original heads are worthy of being worked. I looked up the casting number on Mortec and it shows '75-'86 350/400ci 76cc w/ 1.72", 1.94", or 2.02" intake valve size.
    Q: Has anyone here ever taken one of these L-81 engines apart and know for sure what size valves the heads have? If they're 2.02"/1.60", I may work the original heads instead of buying another set. I've been told by afew people that they do have the big valves, but as detuned as that year is, I have my doubts.
    Thanks in advance f/ any (f/ sure) info.

  2. #2
    Join Date
    May 2003
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    Same answer as in the general forum topic.

    Groeten Peter

  3. #3
    Member black_81_vette's Avatar
    Join Date
    Dec 2002
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    They have 1.94 size intake valves 1.50 exhaust 76 cc chambers thin wall castings basically nothing to write home about. If your going to do a top end build up any aftermarket head with 64 cc or smaller chambers will help add compression and HP.If you really want to wake it up find some small chamber 305 HO heads castings ending with 416 and have 2.02 intakes and 1.60 valves installed(actually there are places on e bay who sell them done) get a good set of headers a decent cam that matches what gear and trans your using and go from there. with a decent top end redo shouldent be hard to get 325 HP from her. Also id ditch the feed back carb and distributor if your allowed too.

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