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Thread: Thinking of some ideas for my 81 vette engine.

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  1. #1
    jchrisd is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2006
    Car Year, Make, Model: 81 corvette

    Thinking of some ideas for my 81 vette engine.


    Hello all, as it has been awhile..Anyway, spring is around the corner, and I have some time in the future, so I wanted to make some mods to my vette this year..But I need some educated opinions...

    Last time I did work to this car was about 2-3 years ago..To update what I did, I will post a list..

    Car was stock, and a dog...SO I STARTED HERE...


    Removed elect-q-jet and replaced with standard q-jet which Lars built
    Removed all computer controls and installed HEI Dist.w/curve kit
    Removed stock manifolds, and installed headers
    Installed true dual exhaust
    Installed a comp cam part #x4250h which is a 4x4 cam for low end
    Installed a 3.73 rear gear set

    Well, it is a noticable difference, but I would say still about a 15-16 second car..closer to 16 in my opinion.

    Anyway, I am not gonna put a ton of money into it, because it is an 81, but the labor is free, as I do it, and I will put some money into certain parts. I would like to maybe have a 13 sec car if possible.

    I had a few ideas..
    Need opinions on these heads, as they would really bump up the compression ratio a fair amount, as stock compression os about 8.2-1

    Heads are 58 cc procomps w/1.60 2.02 valves 210 cfm
    which are done for $535..

    Or, my friend has a set of older fuelie heads that are done, but 64cc
    for $200.. I wwas looking to boost the compression the most.

    Now, with the higher compression, I would be able to run a larger cam, and maybe wake the thing up a bit.

    Was thinking of something like a 280h comp cam..

    I was also think of putting a converter in it, say 2200-2600, but that might not be needed.

    I have a shift kit, which I will install as well.

    I might get rid of the q-jet, and get a holley too, not sure yet, but theer you have it. Any ideas would be wonderful.

    In reguards to the head idea, if I run a steel shim head gasket, that too will bring up the compression if I go with the 64 cc heads.

    Remember, my labor is free, and I have been a tech at a dealer for 18 years, but I really only work on newer cars, and need some old school ideas for this thing. I would be willing to pull the engine and swap the dish pistons for flat tops as well.. Bottom line is I can spend about $1000 in parts to make this thing run better, and I want to spend it correctly. I plan to sell the car once it is fast enough to impress someone, as I really want a 68 Big block camaro w/4speed, then we will spend some money, but we are talking a 81 vette here.

  2. #2
    techinspector1's Avatar
    techinspector1 is offline CHR Member Visit my Photo Gallery
    Join Date
    May 2003
    Zephyrhills, Florida, USA
    Car Year, Make, Model: '32 Henway

    I have many builds in my DynoSim, including several 500hp/500ft/lb builds, but you won't do them for $1000.

  3. #3
    jchrisd is offline CHR Member Visit my Photo Gallery
    Join Date
    Jan 2006
    Car Year, Make, Model: 81 corvette

    Fair enough...We don't really need to be at the 500hp marker..But I will tell you this..The car came stock at 190 hp, and I was hoping for a little more.. I am thinking I am in the 220 range now and was hoping for opinions as to maybe spend $1000 wisely to make the thing get out of it's own way.

    Remember something, I am not new to this, I just haven't built hot rod engines for many years.. 16 years back when I worked in an engine machine shop, I took an old 427 block, bored it >030 on the ck-10 machine, took a set of old closed chambered heads, put a valve job on the with kwick-way stones, cleaned up a cast crank, and put a set of used dome pistons in the block, topped it off with a holley 750 and some cam I ordered from blue racer...Dropped it in my junk 72 camaro with a powerglide, and my 4:56 gears and ran 10.98..That engine and gear set up set me back about $2000, so, I think it is possible (if you have some ability) to make a car run fairly well for cheap. Then again, I built the thing, I didn't simulate it on a computer program.. Any input that has some substance would be helpful..

  4. #4
    Dave Severson is offline CHR Member/Contributor Visit my Photo Gallery
    Join Date
    Jul 2003
    Car Year, Make, Model: '67 Ranchero, '57 Chevy, '82 Camaro,

    16 years ago, $2,000.00 bought a whole lot more then it does today!!!!!

    Don't knock the dyno syms till you've tried them!!! In matching projection off one of Richard's sims that he did for me a few years back, his computer dyno was less then 4% off the actual engine dyno results, and even my weak skills on another sym program indicated the car would run a 10.54---it ran 10.55 with a 6!!!!

    The sym programs will allow you to try a huge variety of parts combinations--even if you should choose to not believe the numbers the program yields, the comparison of the numbers from different combinations will show what combinations work better then others...

    Anyway, the Pro Comp heads leave a lot to be desired in the performance department, seen a lot of people buy them to save the big bucks and be terribly disappointed with the results! Heads and cam really make a small block, or any engine for that matter! Lots of good choices for a SBC in the heads would yield more value then the Pro Comps! Friend of mine just last week picked up a set of Dart cast iron heads used off Craig'slist for $400.00, installed some better springs, hand lapped the valves and they're done....Don't forget the used market, lots of good heads show up, sometimes very reasonably priced....

    For a cam, there again I finally got out of the heresay and 3rd hand gossip and used the numbers from a sym program that was loaded with what the engine really had in it for parts and specs and picked the correct cam first time around....IMO far better a way to decide on which cam is best for a specific combination then taking a guess based on what a concensus of opinions think SHOULD work, or that "trick cam" that made someone's 2nd cousins neigbor's car into a barn burner!!!!

    The sym programs are like any other computer generated product, the more accurate and detailed the information you put in, the better the product that comes out!!! Just another tool to use when planning an engine build!!!!
    Last edited by Dave Severson; 03-11-2010 at 09:31 PM.
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  5. #5
    jchrisd is offline CHR Member Visit my Photo Gallery
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    Jan 2006
    Car Year, Make, Model: 81 corvette

    Thank you for your input, and I happen to agree with engine simulation. My responce was due to the way in which my question was answered.

    And yes, I also agree that 2k did buy alot more back then.

    I had called 2 different cam companies, and got different answers, then I called them back, and got different tech support guys, and now I have 4 different answers.

    Anyway, I guess the bottom line is that I have to raise the compression ratio in order to be able to use a bigger cam to get this thing to run a bit better.

    What do you guys think of the 64 cc fuelie heads and a shim gasket? Maybe run flat tops? (cast) and a any suggestions for a cam with a turbo 350 w/ stock converter as of now? Am I going to far with a higher stall and even bigger cam?

  6. #6
    falconvan's Avatar
    falconvan is offline CHR Member Visit my Photo Gallery
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    Mar 2007
    Car Year, Make, Model: 48 Plymouth, 48,54 Heap

    Best upgrade for a grand on an older SBC? I'd go with Vortec heads, a Performer RPM intake for the Vortec heads (Airgap if available), and a matching cam. Might even have a few $$ left over for a burger.

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